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Tyunina M, Savinov M, Pacherova O, Dejneka A. Small-polaron transport in perovskite nickelates. Sci Rep 2023; 13:12493. [PMID: 37528184 PMCID: PMC10394062 DOI: 10.1038/s41598-023-39821-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 07/31/2023] [Indexed: 08/03/2023] Open
Abstract
Knowledge of the explicit mechanisms of charge transport is preeminent for a fundamental understanding of the metal-to-insulator transition in ABO3-type perovskite rare-earth nickelates and for potential applications of these technologically promising materials. Here we suggest that owing to intrinsic Jahn-Teller-driven carrier localization, small-polaron transport is innate in nickelates. We demonstrate experimental evidence for such transport by investigating AC conductivity over a broad range of temperatures and frequencies in epitaxial SmNiO3 films. We reveal the hopping mechanism of conductivity, Holstein-type activation energy for hopping, nonclassical relaxation behavior, and nonclassical consistency between activation and relaxation. By analyzing these observations, we validate small-polaron transport. We anticipate that our findings can lead to precise tailoring of the DC and AC conductivity in nickelates as requested for fruitful employment of these materials. We also believe that further investigations of self-trapped small polarons are essential for a comprehensive understanding of nickelates.
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Affiliation(s)
- M Tyunina
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18220, Prague, Czech Republic.
- Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, P. O. Box 4500, Fl-90014, Oulu, Finland.
| | - M Savinov
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18220, Prague, Czech Republic
| | - O Pacherova
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18220, Prague, Czech Republic
| | - A Dejneka
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18220, Prague, Czech Republic
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2
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Belyanchikov MA, Savinov M, Bedran ZV, Bednyakov P, Proschek P, Prokleska J, Abalmasov VA, Petzelt J, Zhukova ES, Thomas VG, Dudka A, Zhugayevych A, Prokhorov AS, Anzin VB, Kremer RK, Fischer JKH, Lunkenheimer P, Loidl A, Uykur E, Dressel M, Gorshunov B. Dielectric ordering of water molecules arranged in a dipolar lattice. Nat Commun 2020; 11:3927. [PMID: 32764722 PMCID: PMC7411056 DOI: 10.1038/s41467-020-17832-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 07/17/2020] [Indexed: 11/09/2022] Open
Abstract
Intermolecular hydrogen bonds impede long-range (anti-)ferroelectric order of water. We confine H2O molecules in nanosized cages formed by ions of a dielectric crystal. Arranging them in channels at a distance of ~5 Å with an interchannel separation of ~10 Å prevents the formation of hydrogen networks while electric dipole-dipole interactions remain effective. Here, we present measurements of the temperature-dependent dielectric permittivity, pyrocurrent, electric polarization and specific heat that indicate an order-disorder ferroelectric phase transition at T0 ≈ 3 K in the water dipolar lattice. Ab initio molecular dynamics and classical Monte Carlo simulations reveal that at low temperatures the water molecules form ferroelectric domains in the ab-plane that order antiferroelectrically along the channel direction. This way we achieve the long-standing goal of arranging water molecules in polar order. This is not only of high relevance in various natural systems but might open an avenue towards future applications in biocompatible nanoelectronics. Despite the apparent simplicity of a H2O molecule, the mutual ferroelectric ordering of the molecules is unresolved. Here, the authors realize a macroscopic ferroelectric phase transition in a network of dipole-dipole coupled water molecules located in nanopores of gemstone.
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Affiliation(s)
- M A Belyanchikov
- Moscow Institute of Physics and Technology (National Research University), 141701 Dolgoprudny, Moscow Region, Russia.
| | - M Savinov
- Institute of Physics, Czech Academy of Sciences, 18221, Praha 8, Czech Republic
| | - Z V Bedran
- Moscow Institute of Physics and Technology (National Research University), 141701 Dolgoprudny, Moscow Region, Russia
| | - P Bednyakov
- Institute of Physics, Czech Academy of Sciences, 18221, Praha 8, Czech Republic
| | - P Proschek
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, 12116, Prague 2, Czech Republic
| | - J Prokleska
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, 12116, Prague 2, Czech Republic
| | - V A Abalmasov
- Institute of Automation and Electrometry SB RAS, 630090, Novosibirsk, Russia
| | - J Petzelt
- Institute of Physics, Czech Academy of Sciences, 18221, Praha 8, Czech Republic
| | - E S Zhukova
- Moscow Institute of Physics and Technology (National Research University), 141701 Dolgoprudny, Moscow Region, Russia
| | - V G Thomas
- Sobolev Institute of Geology and Mineralogy, RAS, 630090, Novosibirsk, Russia.,Novosibirsk State University, 630090, Novosibirsk, Russia
| | - A Dudka
- Shubnikov Institute of Crystallography, "Crystallography and Photonics", Russian Academy of Sciences, 119333, Moscow, Russia
| | - A Zhugayevych
- Skolkovo Institute of Science and Technology, 143026, Moscow, Russia
| | - A S Prokhorov
- Moscow Institute of Physics and Technology (National Research University), 141701 Dolgoprudny, Moscow Region, Russia.,Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, Russia
| | - V B Anzin
- Moscow Institute of Physics and Technology (National Research University), 141701 Dolgoprudny, Moscow Region, Russia.,Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, Russia
| | - R K Kremer
- Max-Planck-Institut für Festkörperforschung, 70569, Stuttgart, Germany
| | - J K H Fischer
- Experimental Physics V, University of Augsburg, 86135, Augsburg, Germany.,T. Kimura Lab, Department of Advanced Materials Science, University of Tokyo, Tokyo, Japan
| | - P Lunkenheimer
- Experimental Physics V, University of Augsburg, 86135, Augsburg, Germany
| | - A Loidl
- Experimental Physics V, University of Augsburg, 86135, Augsburg, Germany
| | - E Uykur
- 1.Physikalisches Institut, Universität Stuttgart, 70569, Stuttgart, Germany
| | - M Dressel
- Moscow Institute of Physics and Technology (National Research University), 141701 Dolgoprudny, Moscow Region, Russia.,1.Physikalisches Institut, Universität Stuttgart, 70569, Stuttgart, Germany
| | - B Gorshunov
- Moscow Institute of Physics and Technology (National Research University), 141701 Dolgoprudny, Moscow Region, Russia.
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3
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Tyunina M, Pacherova O, Peräntie J, Savinov M, Jelinek M, Jantunen H, Dejneka A. Perovskite ferroelectric tuned by thermal strain. Sci Rep 2019; 9:3677. [PMID: 30842509 PMCID: PMC6403324 DOI: 10.1038/s41598-019-40260-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 02/12/2019] [Indexed: 12/05/2022] Open
Abstract
Modern environmental and sustainability issues as well as the growing demand for applications in the life sciences and medicine put special requirements to the chemical composition of many functional materials. To achieve desired performance within these requirements, innovative approaches are needed. In this work, we experimentally demonstrate that thermal strain can effectively tune the crystal structure and versatile properties of relatively thick films of environmentally friendly, biocompatible, and low-cost perovskite ferroelectric barium titanate. The strain arises during post-deposition cooling due to a mismatch between the thermal expansion coefficients of the films and the substrate materials. The strain-induced in-plane polarization enables excellent performance of bottom-to-top barium titanate capacitors akin to that of exemplary lead-containing relaxor ferroelectrics. Our work shows that controlling thermal strain can help tailor response functions in a straightforward manner.
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Affiliation(s)
- M Tyunina
- Microelectronics Research Unit, University of Oulu, P.O. Box 4500, FI-90014, Oulu, Finland. .,Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221, Prague, Czech Republic.
| | - O Pacherova
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221, Prague, Czech Republic
| | - J Peräntie
- Microelectronics Research Unit, University of Oulu, P.O. Box 4500, FI-90014, Oulu, Finland
| | - M Savinov
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221, Prague, Czech Republic
| | - M Jelinek
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221, Prague, Czech Republic
| | - H Jantunen
- Microelectronics Research Unit, University of Oulu, P.O. Box 4500, FI-90014, Oulu, Finland
| | - A Dejneka
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221, Prague, Czech Republic
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4
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Motovilov KA, Grinenko V, Savinov M, Gagkaeva ZV, Kadyrov LS, Pronin AA, Bedran ZV, Zhukova ES, Mostert AB, Gorshunov BP. Redox chemistry in the pigment eumelanin as a function of temperature using broadband dielectric spectroscopy. RSC Adv 2019; 9:3857-3867. [PMID: 35518099 PMCID: PMC9060503 DOI: 10.1039/c8ra09093a] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 01/22/2019] [Indexed: 12/12/2022] Open
Abstract
We demonstrate on synthetic eumelanin that biomolecular conductivity models should account for temperature and hydration effects coherently.
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Affiliation(s)
| | - V. Grinenko
- Institute for Solid State and Materials Physics
- TU Dresden
- Dresden
- Germany
- Institute for Metallic Materials
| | - M. Savinov
- Institute of Physics AS CR
- Praha 8
- Czech Republic
| | | | | | - A. A. Pronin
- Prokhorov General Physics Institute of the Russian Academy of Sciences
- Moscow
- Russia
| | - Z. V. Bedran
- Moscow Institute of Physics and Technology
- Russia
| | - E. S. Zhukova
- Moscow Institute of Physics and Technology
- Russia
- Prokhorov General Physics Institute of the Russian Academy of Sciences
- Moscow
- Russia
| | | | - B. P. Gorshunov
- Moscow Institute of Physics and Technology
- Russia
- Prokhorov General Physics Institute of the Russian Academy of Sciences
- Moscow
- Russia
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5
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Zhukova ES, Belyanchikov M, Savinov M, Bednyakov P, Thomas V, Kadyrov L, Simchuk E, Bedran Z, Torgashev V, Dudka A, Dressel M, Gorshunov B. H2O Molecules Hosted By A Crystalline Matrix – New State Of Water? EPJ Web Conf 2018. [DOI: 10.1051/epjconf/201819506018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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6
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Buixaderas E, Kadlec C, Kempa M, Bovtun V, Savinov M, Bednyakov P, Hlinka J, Dec J. Fast polarization mechanisms in the uniaxial tungsten-bronze relaxor strontium barium niobate SBN-81. Sci Rep 2017; 7:18034. [PMID: 29269739 PMCID: PMC5740167 DOI: 10.1038/s41598-017-18252-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 12/07/2017] [Indexed: 11/09/2022] Open
Abstract
The high-frequency dielectric response of the uniaxial strontium barium niobate crystals with 81% of Sr has been studied from 1 kHz to 30 THz along the polar c axis by means of several techniques (far infrared, time domain terahertz, high-frequency and low-frequency dielectric spectroscopies) in a wide temperature interval 20–600 K. Relaxor properties were observed in the complex dielectric response and four main excitations were ascertained below the phonon frequencies. These fast polarization mechanisms take place at THz, GHz and MHz ranges and show different temperature evolution. The central mode excitation in the THz range, related to anharmonic dynamics of cations, slightly softens from high temperatures and then hardens below T ~ 400 K. Below the phase transition (at T ~ 330 K) an additional microwave excitation appears near 10 GHz related to micro domain wall oscillations. The strongest relaxation appears in the GHz range and slows down on cooling according to the Arrhenius law. Finally, another relaxation, present in the MHz range at high temperatures, also slows down on cooling at least to the kHz range. These two relaxations are due to polar fluctuations and nanodomains dynamics. Altogether, the four excitations explain the dielectric permittivity maximum in the kHz range.
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Affiliation(s)
- E Buixaderas
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221, Prague, Czech Republic.
| | - C Kadlec
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221, Prague, Czech Republic
| | - M Kempa
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221, Prague, Czech Republic
| | - V Bovtun
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221, Prague, Czech Republic
| | - M Savinov
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221, Prague, Czech Republic
| | - P Bednyakov
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221, Prague, Czech Republic
| | - J Hlinka
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221, Prague, Czech Republic
| | - J Dec
- Institute of Materials Science, University of Silesia, Pl-40-007, Katowice, Poland
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7
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Motovilov KA, Savinov M, Zhukova ES, Pronin AA, Gagkaeva ZV, Grinenko V, Sidoruk KV, Voeikova TA, Barzilovich PY, Grebenko AK, Lisovskii SV, Torgashev VI, Bednyakov P, Pokorný J, Dressel M, Gorshunov BP. Observation of dielectric universalities in albumin, cytochrome C and Shewanella oneidensis MR-1 extracellular matrix. Sci Rep 2017; 7:15731. [PMID: 29147016 PMCID: PMC5691187 DOI: 10.1038/s41598-017-15693-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 10/31/2017] [Indexed: 11/09/2022] Open
Abstract
The electrodynamics of metals is well understood within the Drude conductivity model; properties of insulators and semiconductors are governed by a gap in the electronic states. But there is a great variety of disordered materials that do not fall in these categories and still respond to external field in an amazingly uniform manner. At radiofrequencies delocalized charges yield a frequency-independent conductivity σ 1(ν) whose magnitude exponentially decreases while cooling. With increasing frequency, dispersionless conductivity starts to reveal a power-law dependence σ 1(ν)∝ν s with s < 1 caused by hopping charge carriers. At low temperatures, such Universal Dielectric Response can cross over to another universal regime with nearly constant loss ε″∝σ1/ν = const. The powerful research potential based on such universalities is widely used in condensed matter physics. Here we study the broad-band (1-1012 Hz) dielectric response of Shewanella oneidensis MR-1 extracellular matrix, cytochrome C and serum albumin. Applying concepts of condensed matter physics, we identify transport mechanisms and a number of energy, time, frequency, spatial and temperature scales in these biological objects, which can provide us with deeper insight into the protein dynamics.
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Affiliation(s)
- K A Motovilov
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia.
| | - M Savinov
- Institute of Physics AS CR, Praha 8, Czech Republic
| | - E S Zhukova
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia
- A.M. Prokhorov General Physics Institute, RAS, Moscow, Russia
- 1. Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
| | - A A Pronin
- A.M. Prokhorov General Physics Institute, RAS, Moscow, Russia
| | - Z V Gagkaeva
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia
| | - V Grinenko
- Institute for Metallic Materials, IFW Dresden, Dresden, Germany
| | - K V Sidoruk
- Scientific Center of Russian Federation Research Institute for Genetics and Selection of Industrial Microorganisms, Moscow, Russia
| | - T A Voeikova
- Scientific Center of Russian Federation Research Institute for Genetics and Selection of Industrial Microorganisms, Moscow, Russia
| | - P Yu Barzilovich
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia
| | - A K Grebenko
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia
| | - S V Lisovskii
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia
| | | | - P Bednyakov
- Institute of Physics AS CR, Praha 8, Czech Republic
| | - J Pokorný
- Institute of Physics AS CR, Praha 8, Czech Republic
| | - M Dressel
- 1. Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
- Moscow Institute of Physics and Technology, Institutsky lane 9, Dolgoprudny, Moscow, 141701, Russia
| | - B P Gorshunov
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia.
- A.M. Prokhorov General Physics Institute, RAS, Moscow, Russia.
- 1. Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany.
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8
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Goian V, Kadlec F, Kadlec C, Dabrowski B, Kolesnik S, Chmaissem O, Nuzhnyy D, Kempa M, Bovtun V, Savinov M, Hejtmánek J, Prokleška J, Kamba S. Spectroscopic studies of the ferroelectric and magnetic phase transitions in multiferroic Sr1-xBaxMnO3. J Phys Condens Matter 2016; 28:175901. [PMID: 27023160 DOI: 10.1088/0953-8984/28/17/175901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Dielectric response of perovskite Sr1-xBaxMnO3 (x = 0.43 and 0.45) ceramics was investigated using microwave, THz and infrared spectroscopic techniques in order to study the ferroelectric and antiferromagnetic phase transitions with critical temperatures TC ≈ 350 K and TN ≈ 200 K, respectively. The two lowest-frequency polar phonons are overdamped above TN and they exhibit pronounced softening on heating towards TC. Nevertheless, permittivity ε' in the THz range shows only a small anomaly at TC because the phonon contribution to ε' is rather small. The phonons are coupled with a central mode which provides the main contribution to the dielectric anomaly at TC. Thus, the ferroelectric phase transition has characteristics of a crossover from displacive to order-disorder type. At the same time, the intrinsic THz central peak is partially screened by conductivity and related Maxwell-Wagner relaxation, which dominates the microwave and lower-frequency spectra. Below TN, the ferroelectric distortion markedly decreases, which has an influence on the frequencies of both the central and soft modes. Therefore, ε' in the THz range increases at TN on cooling. In spite of the strong spin-phonon coupling near TN, surprisingly no magnetodielectric effect was observed in the THz spectra upon applying magnetic field of up to 7 T, which is in contradiction with the theoretically expected huge magnetoelectric coupling. We explain this fact as due to the insensitivity of TN to magnetic field.
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Affiliation(s)
- V Goian
- Institute of Physics, The Czech Academy of Sciences, Na Slovance 2,182 21 Prague, Czech Republic
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9
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Hlinka J, Ostapchuk T, Buixaderas E, Kadlec C, Kuzel P, Gregora I, Kroupa J, Savinov M, Klic A, Drahokoupil J, Etxebarria I, Dec J. Multiple soft-mode vibrations of lead zirconate. Phys Rev Lett 2014; 112:197601. [PMID: 24877964 DOI: 10.1103/physrevlett.112.197601] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Indexed: 06/03/2023]
Abstract
Polarized Raman, IR, and time-domain THz spectroscopy of orthorhombic lead zirconate single crystals have yielded a comprehensive picture of temperature-dependent quasiharmonic frequencies of its low-frequency phonon modes. It is argued that these modes primarily involve vibrations of Pb ions and librations of oxygen octahedra. Their relation to phonon modes of the parent cubic phase is proposed. Counts of the observed IR and Raman active modes belonging to distinct irreducible representations agree quite well with group-theory predictions. Analysis of the results yields insight into the phase transition mechanism, involving a soft ferroelectric branch coupled by a trilinear term to another two oxygen octahedra tilt modes.
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Affiliation(s)
- J Hlinka
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - T Ostapchuk
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - E Buixaderas
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - C Kadlec
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - P Kuzel
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - I Gregora
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - J Kroupa
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - M Savinov
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - A Klic
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - J Drahokoupil
- Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - I Etxebarria
- Zientzia eta Teknologia Fakultatea, Euskal Herriko Unibertsitatea, P.K. 644, 48080 Bilbao, Spain
| | - J Dec
- Institute of Materials Science, University of Silesia, Bankowa 12, PL-40-007 Katowice, Poland
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10
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Nuzhnyy D, Savinov M, Bovtun V, Kempa M, Petzelt J, Mayoral B, McNally T. Broad-band conductivity and dielectric spectroscopy of composites of multiwalled carbon nanotubes and poly(ethylene terephthalate) around their low percolation threshold. Nanotechnology 2013; 24:055707. [PMID: 23324357 DOI: 10.1088/0957-4484/24/5/055707] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Composites of multiwalled carbon nanotubes with poly(ethylene terephthalate) (PET-MWCNT) with up to 3 vol% MWCNTs were prepared and characterized by broad-band AC conductivity and dielectric spectroscopy up to the infrared range using several techniques. A very low electrical percolation threshold of 0.07 vol% MWCNTs was revealed from the low-frequency conductivity plateau as well as from DC conductivity, whose values show the same critical power dependence on MWCNT concentration with the exponent t = 4.3. Above the plateau, the AC conductivity increases with frequency up to the THz range, where it becomes overlapped with the absorption of vibrational modes. The temperature dependence down to ~5 K has shown semiconductor behaviour with a concentration-independent but weakly temperature-dependent small activation energy of ~3 meV. The behaviour is compatible with the previously suggested fluctuation-induced tunnelling conductivity model through a thin (~1 nm) polymer contact layer among the adjacent MWCNTs within percolated clusters. At higher frequencies, deviations from the simple universal conductivity behaviour are observed, indicating some distribution of energy barriers for an electron hopping mechanism.
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Affiliation(s)
- D Nuzhnyy
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Praha 8, Czech Republic.
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11
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Kempa M, Kamba S, Savinov M, Maryško M, Frait Z, Vaněk P, Tomczyk M, Vilarinho PM. Bulk dielectric and magnetic properties of PFW-PZT ceramics: absence of magnetically switched-off polarization. J Phys Condens Matter 2010; 22:445902. [PMID: 21403356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We investigated ceramics samples of solid solutions of [PbFe(2/3)W(1/3)O(3)](x)-[PbZr(0.53)Ti(0.47)O(3)](1 - x) (PFW(x)-PZT(1 - x), x = 0.2 and 0.3) by means of broad-band dielectric spectroscopy, differential scanning calorimetry and SQUID magnetometry. We did not confirm the observations of Kumar et al (2009 J. Phys.: Condens. Matter 21 382204), who reported on reversible suppression of ferroelectric polarization in polycrystalline PFW(x)-PZT(1 - x) thin films for magnetic fields above 0.5 T. We did not observe any change of ferroelectric polarization with external magnetic fields up to 3.2 T. Pirc et al (2009 Phys. Rev. B 79 214114) developed a theory explaining the reported large magnetoelectric effect in PFW(x)-PZT(1 - x), taking into account relaxor magnetic and relaxor ferroelectric properties of the system. Our data revealed classical ferroelectric properties below 525 K and 485 K in samples with x = 0.2 and 0.3, respectively. Moreover, paramagnetic behavior was observed down to 4.5 K instead of previously reported relaxor magnetic behavior. It seems that the reported switching-off of ferroelectric polarization in PFW(x)-PZT(1 - x) thin films is not an intrinsic property, but probably an effect of electrodes, interlayers, grain boundaries or second phases presented in polycrystalline thin films.
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Affiliation(s)
- M Kempa
- Institute of Physics, ASCR, Prague, Praha 8, Czech Republic.
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12
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Rushchanskii KZ, Kamba S, Goian V, Vanek P, Savinov M, Prokleska J, Nuzhnyy D, Knízek K, Laufek F, Eckel S, Lamoreaux SK, Sushkov AO, Lezaić M, Spaldin NA. A multiferroic material to search for the permanent electric dipole moment of the electron. Nat Mater 2010; 9:649-654. [PMID: 20639893 DOI: 10.1038/nmat2799] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 06/05/2010] [Indexed: 05/29/2023]
Abstract
We describe the first-principles design and subsequent synthesis of a new material with the specific functionalities required for a solid-state-based search for the permanent electric dipole moment of the electron. We show computationally that perovskite-structure europium barium titanate should exhibit the required large and pressure-dependent ferroelectric polarization, local magnetic moments and absence of magnetic ordering at liquid-helium temperature. Subsequent synthesis and characterization of Eu(0.5)Ba(0.5)TiO(3) ceramics confirm the predicted desirable properties.
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Affiliation(s)
- K Z Rushchanskii
- Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
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Badalyan AG, Azzoni CB, Galinetto P, Mozzati MC, Trepakov VA, Savinov M, Deyneka A, Jastrabik L, Rosa J. Impurity centers and host microstructure in weakly doped SrTiO3:Mn crystals: new findings. ACTA ACUST UNITED AC 2007. [DOI: 10.1088/1742-6596/93/1/012012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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