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Revealing an important role of piezoelectric polymers in nervous-tissue regeneration: A review. Mater Today Bio 2024; 25:100950. [PMID: 38318479 PMCID: PMC10840125 DOI: 10.1016/j.mtbio.2024.100950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/12/2023] [Accepted: 01/08/2024] [Indexed: 02/07/2024] Open
Abstract
Nerve injuries pose a drastic threat to nerve mobility and sensitivity and lead to permanent dysfunction due to low regenerative capacity of mature neurons. The electrical stimuli that can be provided by electroactive materials are some of the most effective tools for the formation of soft tissues, including nerves. Electric output can provide a distinctly favorable bioelectrical microenvironment, which is especially relevant for the nervous system. Piezoelectric biomaterials have attracted attention in the field of neural tissue engineering owing to their biocompatibility and ability to generate piezoelectric surface charges. In this review, an outlook of the most recent achievements in the field of piezoelectric biomaterials is described with an emphasis on piezoelectric polymers for neural tissue engineering. First, general recommendations for the design of an optimal nerve scaffold are discussed. Then, specific mechanisms determining nerve regeneration via piezoelectric stimulation are considered. Activation of piezoelectric responses via natural body movements, ultrasound, and magnetic fillers is also examined. The use of magnetoelectric materials in combination with alternating magnetic fields is thought to be the most promising due to controllable reproducible cyclic deformations and deep tissue permeation by magnetic fields without tissue heating. In vitro and in vivo applications of nerve guidance scaffolds and conduits made of various piezopolymers are reviewed too. Finally, challenges and prospective research directions regarding piezoelectric biomaterials promoting nerve regeneration are discussed. Thus, the most relevant scientific findings and strategies in neural tissue engineering are described here, and this review may serve as a guideline both for researchers and clinicians.
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Novel Biocompatible Magnetoelectric MnFe 2 O 4 Core@BCZT Shell Nano-Hetero-Structures with Efficient Catalytic Performance. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2302808. [PMID: 37357170 DOI: 10.1002/smll.202302808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/29/2023] [Indexed: 06/27/2023]
Abstract
Magnetoelectric (ME) small-scale robotic devices attract great interest from the scientific community due to their unique properties for biomedical applications. Here, novel ME nano hetero-structures based on the biocompatible magnetostrictive MnFe2 O4 (MFO) and ferroelectric Ba0.85 Ca0.15 Zr0.1 Ti0.9 O3 (BCZT) are developed solely via the hydrothermal method for the first time. An increase in the temperature and duration of the hydrothermal synthesis results in increasing the size, improving the purity, and inducing morphology changes of MFO nanoparticles (NPs). A successful formation of a thin epitaxial BCZT-shell with a 2-5 nm thickness is confirmed on the MFO NPs (77 ± 14 nm) preliminarily treated with oleic acid (OA) or polyvinylpyrrolidone (PVP), whereas no shell is revealed on the surface of pristine MFO NPs. High magnetization is revealed for the developed ME NPs based on PVP- and OA-functionalized MFO NPs (18.68 ± 0.13 and 20.74 ± 0.22 emu g-1 , respectively). Moreover, ME NPs demonstrate 95% degradation of a model pollutant Rhodamine B within 2.5 h under an external AC magnetic field (150 mT, 100 Hz). Thus, the developed biocompatible core-shell ME NPs of MFO and BCZT can be considered as a promising tool for non-invasive biomedical applications, environmental remediation, and hydrogen generation for renewable energy sources.
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Piezo-Responsive Hydrogen-Bonded Frameworks Based on Vanillin-Barbiturate Conjugates. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27175659. [PMID: 36080425 PMCID: PMC9457948 DOI: 10.3390/molecules27175659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 08/25/2022] [Accepted: 09/01/2022] [Indexed: 11/18/2022]
Abstract
A concept of piezo-responsive hydrogen-bonded π-π-stacked organic frameworks made from Knoevenagel-condensed vanillin–barbiturate conjugates was proposed. Replacement of the substituent at the ether oxygen atom of the vanillin moiety from methyl (compound 3a) to ethyl (compound 3b) changed the appearance of the products from rigid rods to porous structures according to optical microscopy and scanning electron microscopy (SEM), and led to a decrease in the degree of crystallinity of corresponding powders according to X-ray diffractometry (XRD). Quantum chemical calculations of possible dimer models of vanillin–barbiturate conjugates using density functional theory (DFT) revealed that π-π stacking between aryl rings of the vanillin moiety stabilized the dimer to a greater extent than hydrogen bonding between carbonyl oxygen atoms and amide hydrogen atoms. According to piezoresponse force microscopy (PFM), there was a notable decrease in the vertical piezo-coefficient upon transition from rigid rods of compound 3a to irregular-shaped aggregates of compound 3b (average values of d33 coefficient corresponded to 2.74 ± 0.54 pm/V and 0.57 ± 0.11 pm/V), which is comparable to that of lithium niobate (d33 coefficient was 7 pm/V).
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A comprehensive study of the structure and piezoelectric response of biodegradable polyhydroxybutyrate-based films for tissue engineering applications. Polym J 2022. [DOI: 10.1038/s41428-022-00662-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Magnetoactive electrospun hybrid scaffolds based on poly(vinylidene fluoride‐co‐trifluoroethylene) and magnetite particles with varied sizes. POLYM ENG SCI 2022. [DOI: 10.1002/pen.25947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Core-Shell Magnetoactive PHB/Gelatin/Magnetite Composite Electrospun Scaffolds for Biomedical Applications. Polymers (Basel) 2022; 14:polym14030529. [PMID: 35160518 PMCID: PMC8839593 DOI: 10.3390/polym14030529] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/21/2022] [Accepted: 01/26/2022] [Indexed: 12/21/2022] Open
Abstract
Novel hybrid magnetoactive composite scaffolds based on poly(3-hydroxybutyrate) (PHB), gelatin, and magnetite (Fe3O4) were fabricated by electrospinning. The morphology, structure, phase composition, and magnetic properties of composite scaffolds were studied. Fabrication procedures of PHB/gelatin and PHB/gelatin/Fe3O4 scaffolds resulted in the formation of both core-shell and ribbon-shaped structure of the fibers. In case of hybrid PHB/gelatin/Fe3O4 scaffolds submicron-sized Fe3O4 particles were observed in the surface layers of the fibers. The X-ray photoelectron spectroscopy results allowed the presence of gelatin on the fiber surface (N/C ratio–0.11) to be revealed. Incubation of the composite scaffolds in saline for 3 h decreased the amount of gelatin on the surface by more than ~75%. The differential scanning calorimetry results obtained for pure PHB scaffolds revealed a characteristic melting peak at 177.5 °C. The presence of gelatin in PHB/gelatin and PHB/gelatin/Fe3O4 scaffolds resulted in the decrease in melting temperature to 168–169 °C in comparison with pure PHB scaffolds due to the core-shell structure of the fibers. Hybrid scaffolds also demonstrated a decrease in crystallinity from 52.3% (PHB) to 16.9% (PHB/gelatin) and 9.2% (PHB/gelatin/Fe3O4). All the prepared scaffolds were non-toxic and saturation magnetization of the composite scaffolds with magnetite was 3.27 ± 0.22 emu/g, which makes them prospective candidates for usage in biomedical applications.
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Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO 2 Thin Films. ACS APPLIED MATERIALS & INTERFACES 2021; 13:51383-51392. [PMID: 34694130 DOI: 10.1021/acsami.1c15875] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Zirconia- and hafnia-based thin films have attracted tremendous attention in the past decade because of their unexpected ferroelectric behavior at the nanoscale, which enables the downscaling of ferroelectric devices. The present work reports an unprecedented ferroelectric rhombohedral phase of ZrO2 that can be achieved in thin films grown directly on (111)-Nb:SrTiO3 substrates by ion-beam sputtering. Structural and ferroelectric characterizations reveal (111)-oriented ZrO2 films under epitaxial compressive strain exhibiting switchable ferroelectric polarization of about 20.2 μC/cm2 with a coercive field of 1.5 MV/cm. Moreover, the time-dependent polarization reversal characteristics of Nb:SrTiO3/ZrO2/Au film capacitors exhibit typical bell-shaped curve features associated with the ferroelectric domain reversal and agree well with the nucleation limited switching (NLS) model. The polarization-electric field hysteresis loops point to an activation field comparable to the coercive field. Interestingly, the studied films show ferroelectric behavior per se, without the need to apply the wake-up cycle found in the orthorhombic phase of ZrO2. Overall, the rhombohedral ferroelectric ZrO2 films present technological advantages over the previously studied zirconia- and hafnia-based thin films and may be attractive for nanoscale ferroelectric devices.
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Hybrid Triboelectric-Electromagnetic Nanogenerators for Mechanical Energy Harvesting: A Review. NANO-MICRO LETTERS 2021; 13:199. [PMID: 34542731 PMCID: PMC8452823 DOI: 10.1007/s40820-021-00713-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 07/26/2021] [Indexed: 05/27/2023]
Abstract
Motion-driven electromagnetic-triboelectric energy generators (E-TENGs) hold a great potential to provide higher voltages, higher currents and wider operating bandwidths than both electromagnetic and triboelectric generators standing alone. Therefore, they are promising solutions to autonomously supply a broad range of highly sophisticated devices. This paper provides a thorough review focused on major recent breakthroughs in the area of electromagnetic-triboelectric vibrational energy harvesting. A detailed analysis was conducted on various architectures including rotational, pendulum, linear, sliding, cantilever, flexible blade, multidimensional and magnetoelectric, and the following hybrid technologies. They enable highly efficient ways to harvest electric energy from many forms of vibrational, rotational, biomechanical, wave, wind and thermal sources, among others. Open-circuit voltages up to 75 V, short-circuit currents up to 60 mA and instantaneous power up to 144 mW were already achieved by these nanogenerators. Their transduction mechanisms, including proposed models to make intelligible the involved physical phenomena, are also overviewed here. A comprehensive analysis was performed to compare their respective construction designs, external excitations and electric outputs. The results highlight the potential of hybrid E-TENGs to convert unused mechanical motion into electric energy for both large- and small-scale applications. Finally, this paper proposes future research directions toward optimization of energy conversion efficiency, power management, durability and stability, packaging, energy storage, operation input, research of transduction mechanisms, quantitative standardization, system integration, miniaturization and multi-energy hybrid cells.
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Local Polarization Reversal by Ion Beam Irradiation in SBN Single Crystals Covered by Dielectric Layer. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:2824-2831. [PMID: 33970859 DOI: 10.1109/tuffc.2021.3078447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Formation of the domain structure by ion beam irradiation was studied in thermally depolarized Ce-doped strontium barium niobate single crystals covered by a dielectric layer. Three types of irradiation regimes were used: dot exposure, stripe exposure, and line exposure. The dependences of the domain size and depth on the irradiated dose were measured. The circular shape of the isolated domains with partially switched broad domain boundary was obtained. Isotropic domain growth was attributed to the step generation at the wall by merging with the residual nanodomains that appeared after thermal depolarization. The obtained linear dose dependence of the switched area was attributed to the screening of the depolarization field by the injected charge. The shape distortion of the domains growing in the neighborhood with already created ones was attributed to the electrostatic interaction of the approaching charged domain walls. The obtained results can be applied for the creation of precise domain patterns with arbitrary orientation and shape to produce nonlinear optical devices with improved characteristics, including electrically tunable diffractive optical elements.
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Local electronic transport across probe/ionic conductor interface in scanning probe microscopy. Ultramicroscopy 2020; 220:113147. [PMID: 33130324 DOI: 10.1016/j.ultramic.2020.113147] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 09/29/2020] [Accepted: 10/15/2020] [Indexed: 11/25/2022]
Abstract
Charge carrier transport through the probe-sample junction can have substantial consequences for outcomes of electrical and electromechanical atomic-force-microscopy (AFM) measurements. For understanding physical processes under the probe, we carried out conductive-AFM (C-AFM) measurements of local current-voltage (I-V) curves as well as their derivatives on samples of a mixed ionic-electronic conductor Li1-xMn2O4 and developed an analytical framework for the data analysis. The implemented approach discriminates between contributions the highly resistive sample surface layer and the bulk with the account of ion redistribution in the field of the probe. It was found that, with increasing probe voltage, the conductance mechanism in the surface layer transforms from Pool-Frenkel to space-charge-limited current. The surface layer significantly alters the ion dynamics in the sample bulk under the probe, which leads, in particular, to a decrease of the effective electromechanical AFM signal associated with the ionic motion in the sample. The framework can be applied for the analysis of electronic transport mechanisms across the probe/sample interface as well as to uncover the role of the charge transport in the electric field distribution, mechanical, and other responses in AFM measurements of a broad spectrum of conducting materials.
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Piezoelectric Actuation of Graphene-Coated Polar Structures. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2020; 67:2142-2147. [PMID: 32746170 DOI: 10.1109/tuffc.2020.2998976] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ferroelectric materials based on lead zirconate titanate (PZT) are widely used as sensors and actuators because of their strong piezoelectric activity. However, their application is limited because of the high processing temperature, brittleness, lack of conformal deposition, and a limited possibility to be integrated with the microelectromechanical systems (MEMS). Recent studies on the piezoelectricity in the 2-D materials have demonstrated their potential in these applications, essentially due to their flexibility and integrability with the MEMS. In this work, we deposited a few layer graphene (FLG) on the amorphous oxidized Si3N4 membranes and studied their piezoelectric response by sensitive laser interferometry and rigorous finite-element modeling (FEM) analysis. Modal analysis by FEM and comparison with the experimental results show that the driving force for the piezoelectric-like response can be a polar interface layer formed between the residual oxygen in Si3N4 and the FLG. The response was about 14 nm/V at resonance and could be further enhanced by adjusting the geometry of the device. These phenomena are fully consistent with the earlier piezoresponse force microscopy (PFM) observations of the piezoelectricity of the graphene on SiO2 and open up an avenue for using graphene-coated structures in the MEMS.
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Piezoelectric Properties of Pb 1-xLa x(Zr 0.52Ti 0.48) 1-x/4O 3 Thin Films Studied by In Situ X-ray Diffraction. MATERIALS (BASEL, SWITZERLAND) 2020; 13:ma13153338. [PMID: 32727047 PMCID: PMC7435409 DOI: 10.3390/ma13153338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 06/11/2023]
Abstract
The piezoelectric properties of lanthanum-modified lead zirconate titanate Pb1-xLax(Zr0.52Ti0.48)1-x/4O3 thin films, with x = 0, 3 and 12 mol% La, were studied by in situ synchrotron X-ray diffraction under direct (DC) and alternating (AC) electric fields, with AC frequencies covering more than four orders of magnitude. The Bragg reflections for thin films with low lanthanum concentration exhibit a double-peak structure, indicating two contributions, whereas thin films with 12% La possess a well-defined Bragg peak with a single component. In addition, built-in electric fields are revealed for low La concentrations, while they are absent for thin films with 12% of La. For static and low frequency AC electric fields, all lanthanum-modified lead zirconate titanate thin films exhibit butterfly loops, whereas linear piezoelectric behavior is found for AC frequencies larger than 1 Hz.
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Efficient Water Self-Diffusion in Diphenylalanine Peptide Nanotubes. ACS APPLIED MATERIALS & INTERFACES 2020; 12:27485-27492. [PMID: 32463652 DOI: 10.1021/acsami.0c03658] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Nanotubes of self-assembled dipeptides exemplified by diphenylalanine (FF) demonstrate a wide range of useful functional properties, such as high Young's moduli, strong photoluminescence, remarkable piezoelectricity and pyroelectricity, optical waveguiding, etc., and became the object of intensive research due to their ability to combine electronic and biological functions in the same material. Two types of nanoconfined water molecules (bound water directly interacting with the peptide backbone and free water located inside nanochannels) are known to play a key role in the self-assembly of FF. Bound water provides its structural integrity, whereas movable free water influences its functional response. However, the intrinsic mechanism of water motion in FF nanotubes remained elusive. In this work, we study the sorption properties of FF nanotubes directly considering them as a microporous material and analyze the free water self-diffusion at different temperatures. We found a change in the regime of free water diffusion, which is attributed to water cluster size in the nanochannels. Small clusters of less than five molecules per unit cell exhibit ballistic diffusion, whereas, for larger clusters, Fickian diffusion occurs. External conditions of around 40% relative humidity at 30 °C enable the formation of such large clusters, for which the diffusion coefficient reaches 1.3 × 10-10 m2 s-1 with an activation energy of 20 kJ mol-1, which increases to attain 3 × 10-10 m2 s-1 at 65 °C. The observed peculiarities of water self-diffusion along the narrow FF nanochannels endow this class of materials with a new functionality. Possible applications of FF nanotubes in nanofluidic devices are discussed.
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Dual Vibration and Magnetic Energy Harvesting With Bidomain LiNbO 3-Based Composite. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2020; 67:1219-1229. [PMID: 31985416 DOI: 10.1109/tuffc.2020.2967842] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
With the recent thriving of low-power electronic microdevices and sensors, the development of components capable of scavenging environmental energy has become imperative. In this article, we studied bidomain congruent LiNbO3 (LN) single crystals combined with magnetic materials for dual, mechanical, and magnetic energy harvesting applications. A simple magneto-mechano-electric composite cantilever, with a trilayered long-bar bidomain LN/spring-steel/metglas structure and a large tip proof permanent magnet, was fabricated. Its vibration and magnetic energy harvesting capabilities were tested while trying to optimize its resonant characteristics, load impedance, and tip proof mass. The vibration measurements yielded a peak open-circuit voltage of 2.42 kV/g, a short-circuit current of [Formula: see text]/g, and an average power of up to 35.6 mW/g2, corresponding to a power density of 6.9 mW/(cm [Formula: see text]), at a low resonance frequency of 29.22 Hz and with an optimal load of 40 [Formula: see text]. The magnetic response revealed a resonant peak open-circuit voltage of 90.9 V/Oe and an average power of up to [Formula: see text]/Oe2, corresponding to a relatively large magnetoelectric coefficient of 1.82 kV/(cm · Oe) and a power density of [Formula: see text]/(cm [Formula: see text]). We thus developed a system that is, in principle, able to scavenge electrical power simultaneously from low-level ambient mechanical and magnetic sources to feed low-power electronic devices.
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To switch or not to switch - a machine learning approach for ferroelectricity. NANOSCALE ADVANCES 2020; 2:2063-2072. [PMID: 36132496 PMCID: PMC9419588 DOI: 10.1039/c9na00731h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 04/06/2020] [Indexed: 05/11/2023]
Abstract
With the advent of increasingly elaborate experimental techniques in physics, chemistry and materials sciences, measured data are becoming bigger and more complex. The observables are typically a function of several stimuli resulting in multidimensional data sets spanning a range of experimental parameters. As an example, a common approach to study ferroelectric switching is to observe effects of applied electric field, but switching can also be enacted by pressure and is influenced by strain fields, material composition, temperature, time, etc. Moreover, the parameters are usually interdependent, so that their decoupling toward univariate measurements or analysis may not be straightforward. On the other hand, both explicit and hidden parameters provide an opportunity to gain deeper insight into the measured properties, provided there exists a well-defined path to capture and analyze such data. Here, we introduce a new, two-dimensional approach to represent hysteretic response of a material system to applied electric field. Utilizing ferroelectric polarization as a model hysteretic property, we demonstrate how explicit consideration of electromechanical response to two rather than one control voltages enables significantly more transparent and robust interpretation of observed hysteresis, such as differentiating between charge trapping and ferroelectricity. Furthermore, we demonstrate how the new data representation readily fits into a variety of machine-learning methodologies, from unsupervised classification of the origins of hysteretic response via linear clustering algorithms to neural-network-based inference of the sample temperature based on the specific morphology of hysteresis.
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Natural and Eco-Friendly Materials for Triboelectric Energy Harvesting. NANO-MICRO LETTERS 2020; 12:42. [PMID: 34138259 PMCID: PMC7770886 DOI: 10.1007/s40820-020-0373-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 12/25/2019] [Indexed: 05/20/2023]
Abstract
Triboelectric nanogenerators (TENGs) are promising electric energy harvesting devices as they can produce renewable clean energy using mechanical excitations from the environment. Several designs of triboelectric energy harvesters relying on biocompatible and eco-friendly natural materials have been introduced in recent years. Their ability to provide customizable self-powering for a wide range of applications, including biomedical devices, pressure and chemical sensors, and battery charging appliances, has been demonstrated. This review summarizes major advances already achieved in the field of triboelectric energy harvesting using biocompatible and eco-friendly natural materials. A rigorous, comparative, and critical analysis of preparation and testing methods is also presented. Electric power up to 14 mW was already achieved for the dry leaf/polyvinylidene fluoride-based TENG devices. These findings highlight the potential of eco-friendly self-powering systems and demonstrate the unique properties of the plants to generate electric energy for multiple applications.
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Domain Switching by Electron Beam Irradiation in SBN61:Ce Single Crystals Covered by Dielectric Layer. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2020; 67:191-196. [PMID: 31484115 DOI: 10.1109/tuffc.2019.2938451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The formation of the domain structure by electron beam irradiation in thermally depolarized Ce-doped strontium barium niobate single crystals with free surface and surface covered by a dielectric layer has been studied. The dependences of the domain sizes and domain depth on the irradiated dose have been measured. The circular shape of the isolated domains was obtained. The isotropic domain growth was attributed to step generation at the wall as a result of merging with the residual nanodomains which existed after thermal depolarization. The linear dose dependence of the switched area was attributed to the screening of the depolarization field by the injected charge. The electrostatic interaction of the approaching charged domain walls was revealed. The better quality of the domain patterns was achieved in the samples with electron localization in the dielectric layer. The obtained results can be applied for the creation of precise domain patterns with arbitrary orientation and shape to produce nonlinear optical devices with improved characteristics.
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Low-Frequency Vibration Energy Harvesting With Bidomain LiNbO 3 Single Crystals. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2019; 66:1480-1487. [PMID: 30990180 DOI: 10.1109/tuffc.2019.2908396] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Low-frequency vibration energy harvesting is becoming increasingly important for environmentally friendly and biomedical applications in order to power various wearable and implanted devices. In this paper, we propose the use of piezoelectric congruent LiNbO3 (LN) single crystals, with an engineered bidomain structure, as an alternative to the widely employed lead-based PZT. We thus compared experimentally the pure vibration energy scavenging performance of square-shaped bidomain and single-domain Y+128°-cut LN crystals and a conventional bimorph soft PZT ceramic bonded to long spring-steel cantilevers as a function of the frequency, load resistance, and tip proof mass. At a low bending resonance frequency of ca. 32.2 Hz, the bidomain LN yielded an open-circuit voltage of 1.54 kV/g, almost one order of magnitude larger than that observed in PZT. The maximum extractable average power was found to be of 9.2 mW/g2 in the bidomain LN, 6.2 mW/g2 in the single-domain LN, and 1.8 mW/g2 in the PZT piezo-elastic cantilevers. With five times higher output power density of up to 11.0 mW/(cm [Formula: see text]) under resonance conditions, bidomain LN was thus shown to be a reliable lead-free and high-temperature alternative to PZT, thanks to its considerably larger quality factor and electromechanical conversion efficiency.
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Nanoplasmonic response of porous Au-TiO 2 thin films prepared by oblique angle deposition. NANOTECHNOLOGY 2019; 30:225701. [PMID: 30754029 DOI: 10.1088/1361-6528/ab068e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this work, a versatile method is proposed to increase the sensitivity of optical sensors based on the localized surface plasmon resonance (LSPR) phenomenon. It combines a physical deposition method with the oblique angle deposition technique, allowing the preparation of plasmonic thin films with tailored porosity. Thin films of Au-TiO2 were deposited by reactive magnetron sputtering in a 3D nanostructure (zigzag growth), at different incidence angles (0° ≤ α ≤ 80°), followed by in-air thermal annealing at 400 °C to induce the growth of the Au nanoparticles. The roughness and surface porosity suffered a gradual increment by increasing the incidence angle. The resulting porous zigzag nanostructures that were obtained also decreased the principal refractive indexes (RIs) of the matrix and favoured the diffusion of Au through grain boundaries, originating broader nanoparticle size distributions. The transmittance minimum of the LSPR band appeared at around 600 nm, leading to a red-shift to about 626 nm for the highest incidence angle α = 80°, due to the presence of larger (scattering) nanoparticles. It is demonstrated that zigzag nanostructures can enhance adsorption sites for LSPR sensing by tailoring the porosity of the thin films. Atmosphere controlled transmittance-LSPR measurements showed that the RI sensitivity of the films is improved for higher incidence angles.
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Domain Diversity and Polarization Switching in Amino Acid β-Glycine. MATERIALS 2019; 12:ma12081223. [PMID: 30991625 PMCID: PMC6514944 DOI: 10.3390/ma12081223] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 03/28/2019] [Accepted: 04/10/2019] [Indexed: 11/28/2022]
Abstract
Piezoelectric materials based on lead zirconate titanate are widely used in sensors and actuators. However, their application is limited because of high processing temperature, brittleness, lack of conformal deposition and, more importantly, intrinsic incompatibility with biological environments. Recent studies on bioorganic piezoelectrics have demonstrated their potential in these applications, essentially due to using the same building blocks as those used by nature. In this work, we used piezoresponse force microscopy (PFM) to study the domain structures and polarization reversal in the smallest amino acid glycine, which recently attracted a lot of attention due to its strong shear piezoelectric activity. In this uniaxial ferroelectric, a diverse domain structure that includes both 180° and charged domain walls was observed, as well as domain wall kinks related to peculiar growth and crystallographic structure of this material. Local polarization switching was studied by applying a bias voltage to the PFM tip, and the possibility to control the resulting domain structure was demonstrated. This study has shown that the as-grown domain structure and changes in the electric field in glycine are qualitatively similar to those found in the uniaxial inorganic ferroelectrics.
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Surface wettability modification of poly(vinylidene fluoride) and copolymer films and membranes by plasma treatment. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.02.042] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Decoupling Mesoscale Functional Response in PLZT across the Ferroelectric-Relaxor Phase Transition with Contact Kelvin Probe Force Microscopy and Machine Learning. ACS APPLIED MATERIALS & INTERFACES 2018; 10:42674-42680. [PMID: 30457324 DOI: 10.1021/acsami.8b15872] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Relaxor ferroelectrics exhibit a range of interesting material behavior, including high electromechanical response, polarization rotations, as well as temperature and electric field-driven phase transitions. The origin of this unusual functional behavior remains elusive due to limited knowledge on polarization dynamics at the nanoscale. Piezoresponse force microscopy and associated switching spectroscopy provide access to local electromechanical properties on the micro- and nanoscale, which can help to address some of these gaps in our knowledge. However, these techniques are inherently prone to artefacts caused by signal contributions emanating from electrostatic interactions between tip and sample. Understanding functional behavior of complex, disordered systems like relaxor materials with unknown electromechanical properties therefore requires a technique that allows distinguishing between electromechanical and electrostatic response. Here, contact Kelvin probe force microscopy (cKPFM) is used to gain insight into the evolution of local electromechanical and capacitive properties of a representative relaxor material lead lanthanum zirconate across the phase transition from a ferroelectric to relaxor state. The obtained multidimensional data set was processed using an unsupervised machine learning algorithm to detect variations in functional response across the probed area and temperature range. Further analysis showed the formation of two separate cKPFM response bands below 50 °C, providing evidence for polarization switching. At higher temperatures only one band is observed, indicating an electrostatic origin of the measured response. In addition, the junction potential difference, which was extracted from the cKPFM data, becomes independent of the temperature in the relaxor state. The combination of this multidimensional voltage spectroscopy technique and machine learning allows to identify the origin of the measured functional response and to decouple ferroelectric from electrostatic phenomena necessary to understand the functional behavior of complex, disordered systems like relaxor materials.
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Diphenylalanine-Based Microribbons for Piezoelectric Applications via Inkjet Printing. ACS APPLIED MATERIALS & INTERFACES 2018; 10:10543-10551. [PMID: 29498259 DOI: 10.1021/acsami.7b19668] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Peptide-based nanostructures are very promising for nanotechnological applications because of their excellent self-assembly properties, biological and chemical flexibility, and unique multifunctional performance. However, one of the limiting factors for the integration of peptide assemblies into functional devices is poor control of their alignment and other geometrical parameters required for device fabrication. In this work, we report a novel method for the controlled deposition of one of the representative self-assembled peptides-diphenylalanine (FF)-using a commercial inkjet printer. The initial FF solution, which has been shown to readily self-assemble into different structures such as nano- and microtubes and microrods, was modified to be used as an efficient ink for the printing of aligned FF-based structures. Furthermore, during the development of the suitable ink, we were able to produce a novel type of FF conformation with high piezoelectric response and excellent stability. By using this method, ribbonlike microcrystals based on FF could be formed and precisely patterned on different surfaces. Possible mechanisms of structure formation and piezoelectric effect in printed microribbons are discussed along with the possible applications.
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Quantitative characterization of the ionic mobility and concentration in Li-battery cathodes via low frequency electrochemical strain microscopy. NANOSCALE 2018; 10:2503-2511. [PMID: 29344595 DOI: 10.1039/c7nr08001h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Electrochemical strain microscopy (ESM) can provide useful information on the ionic processes in materials at the local scale. This is especially important for ever growing applications of Li-batteries whose performance is limited by the intrinsic and extrinsic degradation. However, the ESM method used so far has been only qualitative due to multiple contributions to the apparent ESM signal. In this work, we provide a viable approach for the local probing of ionic concentration and diffusion coefficients based on the frequency dependence of the ESM signal. A theoretical basis considering the dynamic behavior of ion migration and relaxation and change of ion concentration profiles under the action of the electric field of the ESM tip is developed. We argue that several parasitic contributions to the ESM signal discussed in the literature can be thus eliminated. The analysis of ESM images using the proposed approach allows a quantitative mapping of the ionic diffusion coefficients and concentration in ionic conductors. The results are validated on Li-battery cathodes (LiMn2O4) extracted from commercial Li-batteries and can provide novel possibilities for their development and further insight into the mechanisms of their degradation.
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Control of piezoelectricity in amino acids by supramolecular packing. NATURE MATERIALS 2018; 17:180-186. [PMID: 29200197 DOI: 10.1038/nmat5045] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 10/31/2017] [Indexed: 05/21/2023]
Abstract
Piezoelectricity, the linear relationship between stress and induced electrical charge, has attracted recent interest due to its manifestation in biological molecules such as synthetic polypeptides or amino acid crystals, including gamma (γ) glycine. It has also been demonstrated in bone, collagen, elastin and the synthetic bone mineral hydroxyapatite. Piezoelectric coefficients exhibited by these biological materials are generally low, typically in the range of 0.1-10 pm V-1, limiting technological applications. Guided by quantum mechanical calculations we have measured a high shear piezoelectricity (178 pm V-1) in the amino acid crystal beta (β) glycine, which is of similar magnitude to barium titanate or lead zirconate titanate. Our calculations show that the high piezoelectric coefficients originate from an efficient packing of the molecules along certain crystallographic planes and directions. The highest predicted piezoelectric voltage constant for β-glycine crystals is 8 V mN-1, which is an order of magnitude larger than the voltage generated by any currently used ceramic or polymer.
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An atomic force microscopy mode for nondestructive electromechanical studies and its application to diphenylalanine peptide nanotubes. Ultramicroscopy 2017; 185:49-54. [PMID: 29182919 DOI: 10.1016/j.ultramic.2017.11.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/12/2017] [Accepted: 11/19/2017] [Indexed: 10/18/2022]
Abstract
Nondestructive scanning probe microscopy of fragile nanoscale objects is currently in increasing need. In this paper, we report a novel atomic force microscopy mode, HybriD Piezoresponse Force Microscopy (HD-PFM), for simultaneous nondestructive analysis of piezoresponse as well as of mechanical and dielectric properties of nanoscale objects. We demonstrate this mode in application to self-assembled diphenylalanine peptide micro- and nanotubes formed on a gold-covered substrate. Nondestructive in- and out-of-plane piezoresponse measurements of tubes of less than 100 nm in diameter are demonstrated for the first time. High-resolution maps of tube elastic properties were obtained simultaneously with HD-PFM. Analysis of the measurement data combined with the finite-elements simulations allowed quantification of tube Young's modulus. The obtained value of 29 ± 1 GPa agrees well with the data obtained with other methods and reported in the literature.
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Equivalent Magnetic Noise in Magnetoelectric Laminates Comprising Bidomain LiNbO 3 Crystals. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2017; 64:1102-1119. [PMID: 28422658 DOI: 10.1109/tuffc.2017.2694342] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The anisotropic direct magnetoelectric (ME) properties of bilayered composites comprising magnetostrictive metglas foils and single-crystalline piezoelectric bidomain plates of 127°Y-cut LiNbO3 (LNO) have been studied theoretically and experimentally. The LNO plates possessed an engineered ferroelectric macrobidomain structure with opposite spontaneous polarization vectors. Impedance, ME effect, and equivalent magnetic noise density (EMND) measurements have been performed under quasi-static and resonant conditions. Whereas the quasi-static ME effect was only two times stronger in the bidomain samples compared to their unidomain and bonded bimorph counterparts, in the bending resonance mode, the effect was up to one order of magnitude stronger: ME coefficients of up to 578 V/( [Formula: see text]) were obtained at ca. 30 kHz under resonance using 0.5-mm-thick crystals. EMND measurements yielded values down to 153 pT/Hz 1/2 at 1 kHz and 524 fT/Hz 1/2 under resonant conditions. A further optimization of the fabrication techniques, laminate geometry, and detection circuit is expected to allow reducing these values down to at least 10 pT/Hz 1/2 and 250 fT/Hz 1/2 , respectively, and the resonance frequency by at least two orders of magnitude. Such systems may thus find use in simple and sensitive, passive and stable, low frequency and high-temperature vector magnetic field sensors.
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Self-Assembly of Organic Ferroelectrics by Evaporative Dewetting: A Case of β-Glycine. ACS APPLIED MATERIALS & INTERFACES 2017; 9:20029-20037. [PMID: 28534399 DOI: 10.1021/acsami.7b02952] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Self-assembly of ferroelectric materials attracts significant interest because it offers a promising fabrication route to novel structures useful for microelectronic devices such as nonvolatile memories, integrated sensors/actuators, or energy harvesters. In this work, we demonstrate a novel approach for self-assembly of organic ferroelectrics (as exemplified by ferroelectric β-glycine) using evaporative dewetting, which allows forming quasi-regular arrays of nano- and microislands with preferred orientation of polarization axes. Surprisingly, self-assembled islands are crystallographically oriented in a radial direction from the center of organic "grains" formed during dewetting process. The kinetics of dewetting process follows the t-1/2 law, which is responsible for the observed polygon shape of the grain boundaries and island coverage as a function of radial position. The polarization in ferroelectric islands of β-glycine is parallel to the substrate and switchable under a relatively small dc voltage applied by the conducting tip of piezoresponse force microscope. Significant size effect on polarization is observed and explained within the Landau-Ginzburg-Devonshire phenomenological formalism.
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Structural, magnetic, magnetocaloric and specific heat investigations on Mn doped PrCrO 3 orthochromites. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:195802. [PMID: 28288005 DOI: 10.1088/1361-648x/aa666c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have synthesized PrCr0.85Mn0.15O3 (PCMO) chromite and investigated the influence of manganese (Mn) doping at Cr-sites on the structural, magnetic, magnetocaloric and thermal properties of PrCrO3 compound. No structural transition was observed with Mn substitution and the doped compound crystallized into distorted orthorhombic structure with Pnma space group which was confirmed by Rietveld refinement of x-ray powder diffraction patterns. Neel temperature, noticed at 168 K from the temperature variation of magnetization, smaller than that reported for PrCrO3, indicated the influence of Mn3+ substitution in decreasing the antiferromagnetic ordering. Magnetization was almost eight times higher than that reported for undoped sample. Magnetocaloric effect measured via the magnetic entropy change and relative cooling power demonstrated significant values in the temperature range 10-20 K. The values of magnetic entropy change are much superior to that reported for other polycrystalline orthochromites and even at smaller applied field strength. The material exhibited second order magnetic phase transition. The Debye temperature and the density of states at Fermi level were also calculated. The overall results make PrCr0.85Mn0.15O3 chromite a potential candidate to replace the existing materials for low temperature magnetic refrigeration.
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Thermal and aqueous stability improvement of graphene oxide enhanced diphenylalanine nanocomposites. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2017; 18:172-179. [PMID: 28458741 PMCID: PMC5402763 DOI: 10.1080/14686996.2016.1277504] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 12/08/2016] [Accepted: 12/26/2016] [Indexed: 05/23/2023]
Abstract
Nanocomposites of diphenylalanine (FF) and carbon based materials provide an opportunity to overcome drawbacks associated with using FF micro- and nanostructures in nanobiotechnology applications, in particular their poor structural stability in liquid solutions. In this study, FF/graphene oxide (GO) composites were found to self-assemble into layered micro- and nanostructures, which exhibited improved thermal and aqueous stability. Dependent on the FF/GO ratio, the solubility of these structures was reduced to 35.65% after 30 min as compared to 92.4% for pure FF samples. Such functional nanocomposites may extend the use of FF structures to e.g. biosensing, electrochemical, electromechanical or electronic applications.
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Defect chemistry and relaxation processes: effect of an amphoteric substituent in lead-free BCZT ceramics. Phys Chem Chem Phys 2016; 18:31184-31201. [PMID: 27819108 DOI: 10.1039/c6cp06244j] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of praseodymium (Pr), an amphoteric substituent, on phase transition, dielectric relaxation and electrical conductivity has been studied and analysed in 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BCZT) ceramics synthesized by a solid state reaction method. Structural investigations showed co-existence of two phases - tetragonal (P4mm) and rhombohedral (R3m) - for compositions with x ≤ 0.05 wt% Pr. Temperature dependent dielectric studies revealed two phase transitions - rhombohedral (R) → tetragonal (T) and T → cubic (C) - that gradually evolved into one T → C transition for x > 0.05 wt% Pr in BCZT. A dielectric relaxation behaviour was observed in the temperature range of 275-500 °C that was attributed to the localized relaxation process (short-range hopping motion of oxygen vacancies) in the bulk of the material. Grain and grain boundary conductivity evaluated from the impedance data revealed that Pr acts as a donor dopant for x ≤ 0.05 wt% while it is an acceptor for higher concentration, in accordance with XRD observations. Defect chemistry analysis for better interpretation of the acquired data is presented. Frequency and temperature dependent ac conductivity studies were also performed and the obtained activation energy values were associated with possible conduction mechanisms.
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Giant Electric-Field-Induced Strain in PVDF-Based Battery Separator Membranes Probed by Electrochemical Strain Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:5267-5276. [PMID: 27142946 DOI: 10.1021/acs.langmuir.6b01018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Efficiency of lithium-ion batteries largely relies on the performance of battery separator membrane as it controls the mobility and concentration of Li-ions between the anode and cathode electrodes. Recent advances in electrochemical strain microscopy (ESM) prompted the study of Li diffusion and transport at the nanoscale via electromechanical strain developed under an application of inhomogeneous electric field applied via the sharp ESM tip. In this work, we observed unexpectedly high electromechanical strain developed in polymer membranes based on porous poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) and, using it, could study a dynamics of electroosmotic flow of electrolyte inside the pores. We show that, independently of the separator membrane, electric field-induced deformation observed by ESM on wetted membrane surfaces can reach up to 10 nm under a moderate bias of 1 V (i.e., more than an order of magnitude higher than that in best piezoceramics). Such a high strain is explained by the electroosmotic flow in a porous media composed of PVDF. It is shown that the strain-based ESM method can be used to extract valuable information such as average pore size, porosity, elasticity of membrane in electrolyte solvent, and membrane-electrolyte affinity expressed in terms of zeta potential. Besides, such systems can, in principle, serve as actuators even in the absence of apparent piezoelectricity in amorphous PVDF.
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Dual strain mechanisms in a lead-free morphotropic phase boundary ferroelectric. Sci Rep 2016; 6:19630. [PMID: 26791098 PMCID: PMC4726143 DOI: 10.1038/srep19630] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/16/2015] [Indexed: 11/09/2022] Open
Abstract
Electromechanical properties such as d33 and strain are significantly enhanced at morphotropic phase boundaries (MPBs) between two or more different crystal structures. Many actuators, sensors and MEMS devices are therefore systems with MPBs, usually between polar phases in lead (Pb)-based ferroelectric ceramics. In the search for Pb-free alternatives, systems with MPBs between polar and non-polar phases have recently been theorized as having great promise. While such an MPB was identified in rare-earth (RE) modified bismuth ferrite (BFO) thin films, synthesis challenges have prevented its realization in ceramics. Overcoming these, we demonstrate a comparable electromechanical response to Pb-based materials at the polar-to-non-polar MPB in Sm modified BFO. This arises from 'dual' strain mechanisms: ferroelectric/ferroelastic switching and a previously unreported electric-field induced transition of an anti-polar intermediate phase. We show that intermediate phases play an important role in the macroscopic strain response, and may have potential to enhance electromechanical properties at polar-to-non-polar MPBs.
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Wettability gradient-induced alignment of peptide nanotubes as templates for biosensing applications. RSC Adv 2016. [DOI: 10.1039/c6ra05732b] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Peptide nanotubes coated with silver nanoparticles and aligned using wettability-patterned substrates provide improved Raman intensity for biosensing applications.
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Phase stability and dynamics of hybrid organic–inorganic crystals [(CH3)3PH][SbCl4] and [(CH3)3PH][SbBr4]: a computational and NMR approach. CrystEngComm 2016. [DOI: 10.1039/c6ce00160b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Nanoscale Piezoelectric Properties of Self-Assembled Fmoc-FF Peptide Fibrous Networks. ACS APPLIED MATERIALS & INTERFACES 2015; 7:12702-12707. [PMID: 25994251 DOI: 10.1021/acsami.5b01251] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Fibrous peptide networks, such as the structural framework of self-assembled fluorenylmethyloxycarbonyl diphenylalanine (Fmoc-FF) nanofibrils, have mechanical properties that could successfully mimic natural tissues, making them promising materials for tissue engineering scaffolds. These nanomaterials have been determined to exhibit shear piezoelectricity using piezoresponse force microscopy, as previously reported for FF nanotubes. Structural analyses of Fmoc-FF nanofibrils suggest that the observed piezoelectric response may result from the noncentrosymmetric nature of an underlying β-sheet topology. The observed piezoelectricity of Fmoc-FF fibrous networks is advantageous for a range of biomedical applications where electrical or mechanical stimuli are required.
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Local manifestations of a static magnetoelectric effect in nanostructured BaTiO3-BaFe12O9 composite multiferroics. NANOSCALE 2015; 7:4489-4496. [PMID: 25683862 DOI: 10.1039/c4nr05657d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A study on magnetoelectric phenomena in the barium titanate-barium hexaferrite (BaTiO3-BaFe12O19) composite system, using high resolution techniques including switching spectroscopy piezoresponse force microscopy (SSPFM) and spatially resolved confocal Raman microscopy (CRM), is presented. It is found that both the local piezoelectric coefficient and polarization switching parameters change on the application of an external magnetic field. The latter effect is rationalized by the influence of magnetostrictive stress on the domain dynamics. Processing of the Raman spectral data using principal component analysis (PCA) and self-modelling curve resolution (SMCR) allowed us to achieve high resolution phase distribution maps along with separation of average and localized spectral components. A significant effect of the magnetic field on the Raman spectra of the BaTiO3 phase has been revealed. The observed changes are comparable with the classical pressure dependent studies on BaTiO3, confirming the strain mediated character of the magnetoelectric coupling in the studied composites.
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Single- and multi-frequency detection of surface displacements via scanning probe microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2015; 21:154-163. [PMID: 25555020 DOI: 10.1017/s1431927614013622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Piezoresponse force microscopy (PFM) provides a novel opportunity to detect picometer-level displacements induced by an electric field applied through a conducting tip of an atomic force microscope (AFM). Recently, it was discovered that superb vertical sensitivity provided by PFM is high enough to monitor electric-field-induced ionic displacements in solids, the technique being referred to as electrochemical strain microscopy (ESM). ESM has been implemented only in multi-frequency detection modes such as dual AC resonance tracking (DART) and band excitation, where the response is recorded within a finite frequency range, typically around the first contact resonance. In this paper, we analyze and compare signal-to-noise ratios of the conventional single-frequency method with multi-frequency regimes of measuring surface displacements. Single-frequency detection ESM is demonstrated using a commercial AFM.
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Symmetry breaking and electrical frustration during tip-induced polarization switching in the nonpolar cut of lithium niobate single crystals. ACS NANO 2015; 9:769-777. [PMID: 25506745 DOI: 10.1021/nn506268g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Polarization switching in ferroelectric materials is governed by a delicate interplay between bulk polarization dynamics and screening processes at surfaces and domain walls. Here we explore the mechanism of tip-induced polarization switching at nonpolar cuts of uniaxial ferroelectrics. In this case, the in-plane component of the polarization vector switches, allowing for detailed observations of the resultant domain morphologies. We observe a surprising variability of resultant domain morphologies stemming from a fundamental instability of the formed charged domain wall and associated electric frustration. In particular, we demonstrate that controlling the vertical tip position allows the polarity of the switching to be controlled. This represents a very unusual form of symmetry breaking where mechanical motion in the vertical direction controls the lateral domain growth. The implication of these studies for ferroelectric devices and domain wall electronics are discussed.
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Conformational dynamics and aggregation behavior of piezoelectric diphenylalanine peptides in an external electric field. Biophys Chem 2014; 196:16-24. [PMID: 25240398 DOI: 10.1016/j.bpc.2014.08.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 08/27/2014] [Accepted: 08/29/2014] [Indexed: 02/07/2023]
Abstract
Aromatic peptides including diphenylalanine (FF) have the capacity to self-assemble into ordered, biocompatible nanostructures with piezoelectric properties relevant to a variety of biomedical applications. Electric fields are commonly applied to align FF nanotubes, yet little is known about the effect of the electric field on the assembly process. Using all-atom molecular dynamics with explicit water molecules, we examine the response of FF monomers to the application of a constant external electric field over a range of intensities. We probe the aggregation mechanism of FF peptides, and find that the presence of even relatively weak fields can accelerate ordered aggregation, primarily by facilitating the alignment of individual molecular dipole moments. This is modulated by the conformational response of individual FF peptides (e.g., backbone stretching) and by the cooperative alignment of neighboring FF and water molecules. These observations may facilitate future studies on the controlled formation of nanostructured aggregates of piezoelectric peptides and the understanding of their electro-mechanical properties.
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Local bias induced ferroelectricity in manganites with competing charge and orbital order states. Phys Chem Chem Phys 2014; 16:4977-81. [DOI: 10.1039/c4cp00075g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Perovskite-type manganites, such as Pr1−xCaxMnO3, La1−xCaxMnO3 and La1−xSrxMnO3 solid solutions, are set forth as a case study of ferroelectricity formation mechanisms associated with the appearance of site- and bond-centered orbital ordering which breaks structural inversion symmetry.
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Magnetic and structural phase transitions in La0.5Sr0.5CoO(3-δ) (0 ≤ δ < 0.3) cobaltites. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:316004. [PMID: 23838391 DOI: 10.1088/0953-8984/25/31/316004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The evolution of the crystal structure and the magnetic properties was investigated in the La0.5Sr0.5CoO(3-δ) (0 < δ < 0.3) system as a function of the oxygen deficit δ. Compounds with a low oxygen deficit (δ < 0.1) are shown to be predominantly ferromagnetic, while further increase (δ > 0.1) gradually changes the magnetic structure from ferromagnetic to G-type antiferromagnetic and causes a structural transition from rhombohedral to cubic symmetry. Resistivity and magnetoresistance at low temperature increase with increasing of oxygen vacancies. It is argued that oxygen reduction facilitates stabilization of the high spin state of Co(3+) ions. Antiferromagnetic interactions between cobalt ions in the high spin state are found to dominate in compounds with the oxygen deficit δ > 0.18.
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Molecular modeling of the piezoelectric effect in the ferroelectric polymer poly(vinylidene fluoride) (PVDF). J Mol Model 2013; 19:3591-602. [PMID: 23729009 DOI: 10.1007/s00894-013-1891-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 05/14/2013] [Indexed: 10/26/2022]
Abstract
In this work, computational molecular modeling and exploration was applied to study the nature of the negative piezoelectric effect in the ferroelectric polymer polyvinylidene fluoride (PVDF), and the results confirmed by actual nanoscale measurements. First principle calculations were employed, using various quantum-chemical methods (QM), including semi-empirical (PM3) and various density functional theory (DFT) approaches, and in addition combined with molecular mechanics (MM) methods in complex joint approaches (QM/MM). Both PVDF molecular chains and a unit cell of crystalline β-phase PVDF were modeled. This computational molecular exploration clearly shows that the nature of the so-called negative piezo-electric effect in the ferroelectric PVDF polymer has a self-consistent quantum nature, and is related to the redistribution of the electron molecular orbitals (wave functions), leading to the shifting of atomic nuclei and reorganization of all total charges to the new, energetically optimal positions, under an applied electrical field. Molecular modeling and first principles calculations show that the piezoelectric coefficient d 33 has a negative sign, and its average values lies in the range of d 33 ~ -16.6 to -19.2 pC/N (or pm/V) (for dielectric permittivity ε = 5) and in the range of d 33 ~ -33.5 to -38.5 pC/N (or pm/V) (for ε = 10), corresponding to known data, and allowing us to explain the reasons for the negative sign of the piezo-response. We found that when a field is applied perpendicular to the PVDF chain length, as polarization increases the chain also stretches, increasing its length and reducing its height. For computed value of ε ~ 5 we obtained a value of d31 ~ +15.5 pC/N with a positive sign. This computational study is corroborated by measured nanoscale data obtained by atomic force and piezo-response force microscopy (AFM/PFM). This study could be useful as a basis for further insights into other organic and molecular ferroelectrics.
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Local nanoelectromechanical properties of multiferroics Gd-doped BiFeO3-BaTiO3 solid solution. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2012; 12:6639-6644. [PMID: 22962800 DOI: 10.1166/jnn.2012.4559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Bi(1-x-y)GdxBayFe(1-y)TiyO3 (x = 0.1 and y = 0.1, 0.2, 0.3) solid solutions have been prepared via solid state reaction method with the aim to obtaining magnetoelectric coupling (i.e., linear relation between magnetization and electric field) at room temperature. Optimum calcination and sintering strategies for obtaining pure perovskite phase, high density ceramics and homogeneous microstructures have been determined. The maximum ferroelectric transition temperature (Tc) of this system was 150-170 degrees C with the dielectric constant peak of 2300 at 100 kHz for y = 0.1. Well saturated piezoelectric loops were observed for all composition indicating room temperature ferroelectricity. Hardness and Young's modulus decrease with depth and with increasing concentration y.
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Computational and experimental studies of size and shape related physical properties of hydroxyapatite nanoparticles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:065302. [PMID: 21406923 DOI: 10.1088/0953-8984/23/6/065302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this work, the properties of hydroxyapatite (HAP) nanoparticles (NPs) have been studied both theoretically and experimentally focusing on computational analysis. HAP is widely used to fabricate implants, for drug delivery, etc. The physical properties of the nanosized HAP particles play an important role in the interaction with cells in the human body and are of great interest. Computer simulation was employed to understand the properties of HAP clusters (Ca(5)(PO(4))(3)OH) including formation energies, dipole moments and polarization (surface charges) by molecular mechanics (MM + , OPLS) and mostly by quantum semi-empirical Hartree-Fock (PM3) methods. The size of the simulated cluster is found to affect its dipole moment, polarization, and, finally, the electron work function- ϕ. These parameters depend on the concentration of hydrogen atoms H (or protons) at the surface. Values of ϕ were experimentally estimated via photoelectron emission measurements. The magnitude of ϕ was demonstrated to have a positive correlation on sizes. The NPs demonstrated a capability to be gathered within conglomerates. This property is confirmed by the calculated data for various sizes. Their sizes have a positive correlation on ϕ by the native particles. The main results show that the distributions of dipole moments have very different space orientations (along the OX, OY and OZ axes, the OZ axis is oriented along the OH column) and change with the addition of hydrogen atoms, which saturate the broken hydrogen bonds. This electrical property of NP leads to different behaviors and motions with consequent aggregation: (1) for the case of NPs having dipole moment oriented preferably perpendicular to the OZ axis (with more hydrogen bonds saturated by added H)-the HAP NP aggregates with hexagonal orientation and forms a wider and more spherical shape (sphere-like or bundle-like); (2) for the case of NPs having dipole moment oriented along the OZ axis (as is the case in the absence of added protons or non-saturated hydrogen bonds)-the NPs firstly rotated and oriented along this axis to form the most elongated cylindrical shape (rod-like).
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Mapping Disorder in Polycrystalline Relaxors: A Piezoresponse Force Microscopy Approach. MATERIALS 2010; 3:4860-4870. [PMID: 28883357 PMCID: PMC5445776 DOI: 10.3390/ma3114860] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 10/22/2010] [Indexed: 12/03/2022]
Abstract
Relaxors constitute a large class of ferroelectrics where disorder is introduced by doping with ions of different size and valence, in order to maximize their useful properties in a broad temperature range. Polarization disorder in relaxors is typically studied by dielectric and scattering techniques that do not allow direct mapping of relaxor parameters, such as correlation length or width of the relaxation time spectrum. In this paper, we introduce a novel method based on measurements of local vibrations by Piezoresponse Force Microscopy (PFM) that detects nanoscale polarization on the relaxor surface. Random polarization patterns are then analyzed via local Fast Fourier Transform (FFT) and the FFT PFM parameters, such as amplitude, correlation radius and width of the spectrum of spatial correlations, are mapped along with the conventional topography. The results are tested with transparent (Pb, La) (Zr, Ti)O3 ceramics where local disorder is due to doping with La3+. The conclusions are made about the distribution of the defects responsible for relaxor behavior and the role of the grain boundaries in the macroscopic response.
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Thermodynamic theory of strain-mediated direct magnetoelectric effect in multiferroic film-substrate hybrids. NANOTECHNOLOGY 2010; 21:265701. [PMID: 20522925 DOI: 10.1088/0957-4484/21/26/265701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A nonlinear thermodynamic theory is developed for the strain-mediated direct magnetoelectric (ME) effect displayed by ferroelectric-ferromagnetic nanostructures. This effect results from transmission of magnetic-field-induced deformations of a thick ferromagnetic substrate to a thin ferroelectric overlayer, where the polarization changes due to lattice strains. The strain-dependent polarization and permittivity of an epitaxial nanolayer (few tens of nm thick) are calculated using the thermodynamic theory of single-domain ferroelectric films. The substrate magnetostrictive deformations are described phenomenologically, taking into account their nonlinear variation with magnetic field. The calculations show that ME polarization and voltage coefficients strongly depend on the initial strain state of the film. For BaTiO(3) and PbTiO(3) films deposited on Co(0.8)Zn(0.2)Fe(2)O(4), the out-of-plane polarization and related ME coefficients are calculated numerically as a function of magnetic field parallel to the interface. For films stabilized in the monoclinic phase, this transverse ME response depends on the orientation of magnetic field relative to their in-plane crystallographic axes. The longitudinal ME coefficient is also evaluated and, for a substrate geometry minimizing the demagnetizing field, predicted to be comparable to the transverse one. For BaTiO(3) and PbTiO(3) films deposited on Terfenol-D, the calculations yield high ME polarization coefficients approximately 10(-7) s m(-1) and giant ME voltage coefficients approximately 50 V cm(-1) Oe(-1).
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Local piezoelectric properties of ZnO thin films prepared by RF-plasma-assisted pulsed-laser deposition method. NANOTECHNOLOGY 2010; 21:235703. [PMID: 20463382 DOI: 10.1088/0957-4484/21/23/235703] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Zinc oxide (ZnO) thin films were grown on uncoated and zinc-coated Corning glass substrates by pulsed-laser deposition (PLD). X-ray diffraction measurements revealed that the as-deposited films are polycrystalline having preferential orientation along the [0002] and [[Formula: see text]] directions. Transmittance spectroscopy verified that the as-deposited films are transparent with a direct bandgap of about 3.28 eV at room temperature. Piezoresponse imaging and local hysteresis loop acquisition were performed to characterize the piezoelectric and possible ferroelectric properties of the films. The out-of-plane (effective longitudinal, d(parellel)) and in-plane (effective shear, d(perpendicular)) coefficients were estimated from the local piezoresponse based on the comparison with LiNbO(3) single crystals. Measurements of all three components of piezoresponse (one longitudinal and two shear signals) allowed constructing piezoelectric maps for polycrystalline ZnO and to relate the variation of piezoelectric properties to the crystallographic and grain structure of the films. A shifted piezoresponse hysteresis loop under high voltages hints at the possible pseudoferroelectricity, as discussed recently by Tagantsev (2008 Appl. Phys. Lett. 93 202905).
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