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Puretzky AA, Geohegan DB, Pannala S, Rouleau CM, Regmi M, Thonnard N, Eres G. Real-time optical diagnostics of graphene growth induced by pulsed chemical vapor deposition. NANOSCALE 2013; 5:6507-6517. [PMID: 23752798 DOI: 10.1039/c3nr01436c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The kinetics and mechanisms of graphene growth on Ni films at 720-880 °C have been measured using fast pulses of acetylene and real-time optical diagnostics. In situ UV-Raman spectroscopy was used to unambiguously detect isothermal graphene growth at high temperatures, measure the growth kinetics with ∼1 s temporal resolution, and estimate the fractional precipitation upon cooldown. Optical reflectivity and videography provided much faster temporal resolution. Both the growth kinetics and the fractional isothermal precipitation were found to be governed by the C2H2 partial pressure in the CVD pulse for a given film thickness and temperature, with up to ∼94% of graphene growth occurring isothermally within 1 second at 800 °C at high partial pressures. At lower partial pressures, isothermal graphene growth is shown to continue 10 seconds after the gas pulse. These flux-dependent growth kinetics are described in the context of a dissolution/precipitation model, where carbon rapidly dissolves into the Ni film and later precipitates driven by gradients in the chemical potential. The combination of pulsed-CVD and real-time optical diagnostics opens new opportunities to understand and control the fast, sub-second growth of graphene on various substrates at high temperatures.
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Shao M, He Y, Hong K, Rouleau CM, Geohegan DB, Xiao K. A water-soluble polythiophene for organic field-effect transistors. Polym Chem 2013. [DOI: 10.1039/c2py21020g] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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53
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Choi WS, Rouleau CM, Seo SSA, Luo Z, Zhou H, Fister TT, Eastman JA, Fuoss PH, Fong DD, Tischler JZ, Eres G, Chisholm MF, Lee HN. Atomic layer engineering of perovskite oxides for chemically sharp heterointerfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:6423-6428. [PMID: 23034879 DOI: 10.1002/adma.201202691] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/03/2012] [Indexed: 06/01/2023]
Abstract
Atomic layer engineering enables fabrication of a chemically sharp oxide heterointerface. The interface formation and strain evolution during the initial growth of LaAlO(3) /SrTiO(3) heterostructures by pulsed laser deposition are investigated in search of a means for controlling the atomic-sharpness of the interface. This study shows that inserting a monolayer of LaAlO(3) grown at high oxygen pressure dramatically enhances interface abruptness.
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Whitney JR, Rodgers A, Harvie E, Carswell WF, Torti S, Puretzky AA, Rouleau CM, Geohegan DB, Rylander CG, Rylander MN. Spatial and temporal measurements of temperature and cell viability in response to nanoparticle-mediated photothermal therapy. Nanomedicine (Lond) 2012; 7:1729-42. [DOI: 10.2217/nnm.12.66] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: Nanoparticle-enhanced photothermal therapy is a promising alternative to tumor resection. However, quantitative measurements of cellular response to these treatments are limited. This article introduces a Bimodal Enhanced Analysis of Spatiotemporal Temperature (BEAST) algorithm to rapidly determine the viability of cancer cells in vitro following photothermal therapy alone or in combination with nanoparticles. Materials & methods: To illustrate the capability of the BEAST viability algorithm, single wall carbon nanohorns were added to renal cancer (RENCA) cells in vitro and time-dependent spatial temperature maps measured with an infrared camera during laser therapy were correlated with post-treatment cell viability distribution maps obtained by cell-staining fluorescent microscopy. Conclusion: The BEAST viability algorithm accurately and rapidly determined the cell viability as a function of time, space and temperature. Original submitted 13 July 2011; Revised submitted 12 March 2012; Published online 20 July 2012
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Puretzky AA, Geohegan DB, Jackson JJ, Pannala S, Eres G, Rouleau CM, More KL, Thonnard N, Readle JD. Incremental growth of short SWNT arrays by pulsed chemical vapor deposition. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:1534-1542. [PMID: 22419542 DOI: 10.1002/smll.201102173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 12/13/2011] [Indexed: 05/31/2023]
Abstract
Very short arrays of continuous single-wall carbon nanotubes (SWNTs) are grown incrementally in steps as small as 25 nm using pulsed chemical vapor deposition (CVD). In-situ optical extinction measurements indicate that over 98% of the nanotubes reinitiate growth on successive gas pulses, and high-resolution transmission electron microscopy (HR-TEM) images show that the SWNTs do not exhibit segments, caps, or noticeable sidewall defects resulting from repeatedly stopping and restarting growth. Time-resolved laser reflectivity (3-ms temporal resolution) is used to record the nucleation and growth kinetics for each fast (0.2 s) gas pulse and to measure the height increase of the array in situ, providing a method to incrementally grow short nanotube arrays to precise heights. Derivatives of the optical reflectivity signal reveal distinct temporal signatures for both nucleation and growth kinetics, with their amplitude ratio on the first gas pulse serving as a good predictor for the evolution of the growth of the nanotube ensemble into a coordinated array. Incremental growth by pulsed CVD is interpreted in the context of autocatalytic kinetic models as a special processing window in which a sufficiently high flux of feedstock gas drives the nucleation and rapid growth phases of a catalyst nanoparticle ensemble to occur within the temporal period of the gas pulse, but without inducing growth termination.
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Sun Z, Xiao K, Keum JK, Yu X, Hong K, Browning J, Ivanov IN, Chen J, Alonzo J, Li D, Sumpter BG, Payzant EA, Rouleau CM, Geohegan DB. PS-b-P3HT copolymers as P3HT/PCBM interfacial compatibilizers for high efficiency photovoltaics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:5529-5535. [PMID: 22095908 DOI: 10.1002/adma.201103361] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 09/21/2011] [Indexed: 05/31/2023]
Abstract
A conducting diblock copolymer of PS-b-P3HT was added to serve as a compatibilizer in a P3HT/PCBM blend, which improved the power-conversion efficiency from 3.3% to 4.1% due to the enhanced crystallinity, morphology, interface interaction, and depth profile of PCBM.
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Geohegan DB, Puretzky AA, Jackson JJ, Rouleau CM, Eres G, More KL. Flux-dependent growth kinetics and diameter selectivity in single-wall carbon nanotube arrays. ACS NANO 2011; 5:8311-8321. [PMID: 21916517 DOI: 10.1021/nn2030397] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The nucleation and growth kinetics of single-wall carbon nanotubes in aligned arrays have been measured using fast pulses of acetylene and in situ optical diagnostics in conjunction with low pressure chemical vapor deposition (CVD). Increasing the acetylene partial pressure is shown to decrease nucleation times by three orders of magnitude, permitting aligned nanotube arrays to nucleate and grow to micrometers lengths within single gas pulses at high (up to 7 μm/s) peak growth rates and short ∼0.5 s times. Low-frequency Raman scattering (>10 cm(-1)) and transmission electron microscopy measurements show that increasing the feedstock flux in both continuous- and pulsed-CVD shifts the product distribution to large single-wall carbon nanotube diameters >2.5 nm. Sufficiently high acetylene partial pressures in pulsed-CVD appear to temporarily terminate the growth of the fastest-growing, small-diameter nanotubes by overcoating the more catalytically active, smaller catalyst nanoparticles within the ensemble with non-nanotube carbon in agreement with a growth model. The results indicate that subsets of catalyst nanoparticle ensembles nucleate, grow, and terminate growth within different flux ranges according to their catalytic activity.
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Liu X, Sen S, Liu J, Kulaots I, Geohegan D, Kane A, Puretzky AA, Rouleau CM, More KL, Palmore GTR, Hurt RH. Antioxidant deactivation on graphenic nanocarbon surfaces. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2011; 7:2775-85. [PMID: 21818846 PMCID: PMC3634619 DOI: 10.1002/smll.201100651] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 05/25/2011] [Indexed: 05/18/2023]
Abstract
This article reports a direct chemical pathway for antioxidant deactivation on the surfaces of carbon nanomaterials. In the absence of cells, carbon nanotubes are shown to deplete the key physiological antioxidant glutathione (GSH) in a reaction involving dissolved dioxygen that yields the oxidized dimer, GSSG, as the primary product. In both chemical and electrochemical experiments, oxygen is only consumed at a significant steady-state rate in the presence of both nanotubes and GSH. GSH deactivation occurs for single- and multi-walled nanotubes, graphene oxide, nanohorns, and carbon black at varying rates that are characteristic of the material. The GSH depletion rates can be partially unified by surface area normalization, are accelerated by nitrogen doping, and suppressed by defect annealing or addition of proteins or surfactants. It is proposed that dioxygen reacts with active sites on graphenic carbon surfaces to produce surface-bound oxygen intermediates that react heterogeneously with glutathione to restore the carbon surface and complete a catalytic cycle. The direct catalytic reaction between nanomaterial surfaces and antioxidants may contribute to oxidative stress pathways in nanotoxicity, and the dependence on surface area and structural defects suggest strategies for safe material design.
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Lowndes DH, Rouleau CM, Geohegan DB, Puretzky AA, Strauss MA, Pedraza AJ, Park JW, Budai JD, Poker DB. Pulsed Laser Ablation Growth and Doping of Epitaxial Compound Semiconductor Films. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-397-107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTPulsed laser ablation (PLA) has several characteristics that are potentially attractive for the growth and doping of chemically complex compound semiconductors including (1) stoichiometric (congruent) transfer of composition from target to film, (2) the use of reactive gases to control film composition and/or doping via energetic-beam-induced reactions, and (3) low-temperature nonequilibrium phase formation in the laser-generated plasma “plume.” However, the electrical properties of compound semiconductors are far more sensitive to low concentrations of defects than are the oxide metals/ceramics for which PLA has been so successful. Only recently have doped epitaxial compound semiconductor films been grown by PLA. Fundamental studies are being carried out to relate film electrical and microstructural properties to the energy distribution of ablated species, to the temporal evolution of the ablation pulse in ambient gases, and to beam-assisted surface and/or gas-phase reactions. In this paper we describe results of ex situ Hall effect, high-resolution x-ray diffraction, transmission electron microscopy, and Rutherford backscattering measurements that are being used in combination with in situ RHEED and time-resolved ion probe measurements to evaluate PLA for growth of doped epitaxial compound semiconductor films and heterostructures. Examples are presented and results analyzed for doped II–VI, I–III–VI, and column-Ill nitride materials grown recently in this and other laboratories.
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60
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Whitney JR, Sarkar S, Zhang J, Do T, Young T, Manson MK, Campbell TA, Puretzky AA, Rouleau CM, More KL, Geohegan DB, Rylander CG, Dorn HC, Rylander MN. Single walled carbon nanohorns as photothermal cancer agents. Lasers Surg Med 2011; 43:43-51. [DOI: 10.1002/lsm.21025] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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61
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Jackson JJ, Puretzky AA, More KL, Rouleau CM, Eres G, Geohegan DB. Pulsed growth of vertically aligned nanotube arrays with variable density. ACS NANO 2010; 4:7573-7581. [PMID: 21128670 DOI: 10.1021/nn102029y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The density of vertically aligned carbon nanotube arrays is shown to vary significantly during normal growth by chemical vapor deposition and respond rapidly to changes in feedstock flux. Pulsing the feedstock gas to repeatedly stop and start nanotube growth is shown to induce density variations up to a factor of 1.6 within ca. 1-2 μm long layers, allowing the synthesis of new array architectures with distinct regions of controllable length and density variation. Z-Contrast scanning transmission electron microscopy of corresponding sections of the arrays is used to provide unambiguous measurements of these density variations. Time-resolved optical reflectivity measurements of the height and optical extinction coefficient of the growing arrays are shown to provide a real-time diagnostic of both array density and growth kinetics.
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Zhang J, Ge J, Shultz MD, Chung E, Singh G, Shu C, Deck PA, Fatouros PP, Henderson SC, Corwin FD, Geohegan DB, Puretzky AA, Rouleau CM, More K, Rylander C, Rylander MN, Gibson HW, Dorn HC. In vitro and in vivo studies of single-walled carbon nanohorns with encapsulated metallofullerenes and exohedrally functionalized quantum dots. NANO LETTERS 2010; 10:2843-8. [PMID: 20698597 PMCID: PMC2935139 DOI: 10.1021/nl1008635] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Single-walled carbon nanohorns (SWNHs) are new carbonaceous materials. In this paper, we report the first successful preparation of SWNHs encapsulating trimetallic nitride template endohedral metallofullerenes (TNT-EMFs). The resultant materials were functionalized by a high-speed vibration milling method and conjugated with CdSe/ZnS quantum dots (QDs). The successful encapsulation of TNT-EMFs and external functionalization with QDs provide a dual diagnostic platform for in vitro and in vivo biomedical applications of these new carbonaceous materials.
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63
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Bai X, More K, Rouleau CM, Rabiei A. Functionally graded hydroxyapatite coatings doped with antibacterial components. Acta Biomater 2010; 6:2264-73. [PMID: 19969112 DOI: 10.1016/j.actbio.2009.12.002] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 11/26/2009] [Accepted: 12/01/2009] [Indexed: 02/01/2023]
Abstract
A series of functionally graded hydroxyapatite (FGHA) coatings incorporated with various percentages of silver were deposited on titanium substrates using ion beam-assisted deposition. The analysis of the coating's cross-section using transmission electron microscopy (TEM) and scanning transmission electron microscopy equipped with energy dispersive X-ray spectroscopy has shown a decreased crystallinity as well as a distribution of nanoscale (10-50nm) silver particles from the coating/substrate interface to top surface. Both X-ray diffraction and fast Fourier transforms on high-resolution TEM images revealed the presence of hydroxyapatite within the coatings. The amount of Ag (wt.%) on the outer surface of the FGHA, as determined from X-ray photoelectron spectroscopy, ranged from 1.09 to 6.59, which was about half of the average Ag wt.% incorporated in the entire coating. Average adhesion strengths evaluated by pull-off tests were in the range of 83+/-6 to 88+/-3MPa, which is comparable to 85MPa for FGHA without silver. Further optical observations of failed areas illustrated that the dominant failure mechanism was epoxy failure, and FGHA coating delamination was not observed.
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Puretzky AA, Eres G, Rouleau CM, Ivanov IN, Geohegan DB. Real-time imaging of vertically aligned carbon nanotube array growth kinetics. NANOTECHNOLOGY 2008; 19:055605. [PMID: 21817613 DOI: 10.1088/0957-4484/19/05/055605] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In situ time-lapse photography and laser irradiation are applied to understand unusual coordinated growth kinetics of vertically aligned carbon nanotube arrays including pauses in growth, retraction, and local equilibration in length. A model is presented which explains the measured kinetics and determines the conditions for diffusion-limited growth. Laser irradiation of the growing nanotube arrays is first used to prove that the nanotubes grow from catalyst particles at their bases, and then increase their growth rate and terminal lengths.
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65
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Jellison GE, Hunn JD, Rouleau CM. Normal-incidence generalized ellipsometry using the two-modulator generalized ellipsometry microscope. APPLIED OPTICS 2006; 45:5479-88. [PMID: 16855646 DOI: 10.1364/ao.45.005479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
A new microscope is described that is capable of measuring the polarization characteristics of materials in normal-incidence reflection with a demonstrated lateral resolution of 4 microm. The instrument measures eight parameters of the sample Mueller matrix, which can be related to the diattenuation, retardation, circular diattenuation, direction of the principal axis, and the polarization factor. With proper calibration, the eight elements of the sample Mueller matrix can be determined to better than 0.001-0.002 for small values. Examples are given for aluminum, rutile (TiO2), and calcite (CaCO3).
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66
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Tischler JZ, Eres G, Larson BC, Rouleau CM, Zschack P, Lowndes DH. Nonequilibrium interlayer transport in pulsed laser deposition. PHYSICAL REVIEW LETTERS 2006; 96:226104. [PMID: 16803326 DOI: 10.1103/physrevlett.96.226104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Indexed: 05/10/2023]
Abstract
We use time-resolved surface x-ray diffraction measurements with microsecond range resolution to study the growth kinetics of pulsed laser deposited . Time-dependent surface coverages corresponding to single laser shots were determined directly from crystal truncation rod intensity transients. Analysis of surface coverage evolution shows that extremely fast nonequilibrium interlayer transport, which occurs concurrently with the arrival of the laser plume, dominates the deposition process. A much smaller fraction of material, which is governed by the dwell time between successive laser shots, is transferred by slow, thermally driven interlayer transport processes.
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67
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Jellison GE, Rouleau CM. Determination of optical birefringence by using off-axis transmission ellipsometry. APPLIED OPTICS 2005; 44:3153-9. [PMID: 15943247 DOI: 10.1364/ao.44.003153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Utilizing transmission ellipsometry at small angles of incidence, it is shown that c-cut uniaxial samples can be used to determine both the miscut of the optic axis with respect to the plane of incidence as well as very accurate values of the spectroscopic birefringence. For example, wafers of ZnO, LiNbO3, and 6H-SiC single-crystals are examined and the miscut direction and the spectroscopic birefringence are determined. While all materials show strong dispersion in birefringence, ZnO exhibits a distinct isotropic point at 396.8 nm.
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Lee HN, Christen HM, Chisholm MF, Rouleau CM, Lowndes DH. Strong polarization enhancement in asymmetric three-component ferroelectric superlattices. Nature 2005. [DOI: 10.1038/nature03517] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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69
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Lee HN, Christen HM, Chisholm MF, Rouleau CM, Lowndes DH. Strong polarization enhancement in asymmetric three-component ferroelectric superlattices. Nature 2005; 433:395-9. [PMID: 15674286 DOI: 10.1038/nature03261] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2004] [Accepted: 12/03/2004] [Indexed: 11/09/2022]
Abstract
Theoretical predictions--motivated by recent advances in epitaxial engineering--indicate a wealth of complex behaviour arising in superlattices of perovskite-type metal oxides. These include the enhancement of polarization by strain and the possibility of asymmetric properties in three-component superlattices. Here we fabricate superlattices consisting of barium titanate (BaTiO3), strontium titanate (SrTiO3) and calcium titanate (CaTiO3) with atomic-scale control by high-pressure pulsed laser deposition on conducting, atomically flat strontium ruthenate (SrRuO3) layers. The strain in BaTiO3 layers is fully maintained as long as the BaTiO3 thickness does not exceed the combined thicknesses of the CaTiO3 and SrTiO3 layers. By preserving full strain and combining heterointerfacial couplings, we find an overall 50% enhancement of the superlattice global polarization with respect to similarly grown pure BaTiO3, despite the fact that half the layers in the superlattice are nominally non-ferroelectric. We further show that even superlattices containing only single-unit-cell layers of BaTiO3 in a paraelectric matrix remain ferroelectric. Our data reveal that the specific interface structure and local asymmetries play an unexpected role in the polarization enhancement.
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70
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Pan ZW, Dai S, Rouleau CM, Lowndes DH. Germanium-Catalyzed Growth of Zinc Oxide Nanowires: A Semiconductor Catalyst for Nanowire Synthesis. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200460043] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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71
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Pan ZW, Dai S, Rouleau CM, Lowndes DH. Germanium-Catalyzed Growth of Zinc Oxide Nanowires: A Semiconductor Catalyst for Nanowire Synthesis. Angew Chem Int Ed Engl 2005; 44:274-8. [PMID: 15614907 DOI: 10.1002/anie.200460043] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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72
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Jellison GE, Griffiths CO, Holcomb DE, Rouleau CM. Transmission two-modulator generalized ellipsometry measurements. APPLIED OPTICS 2002; 41:6555-6566. [PMID: 12412646 DOI: 10.1364/ao.41.006555] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The two-modulator generalized ellipsometer has been used to measure samples in transmission. In this configuration, the instrument can completely characterize a linear diattenuator and retarder, measuring birefringence, diattenuation, the angle of the principal axis, and the sample depolarization simultaneously and accurately. This instrument can be operated in two modes: (1) spectroscopic, in which measurements are made through the entire sample aperture as a function of wavelength, and (2) spatially resolved, in which measurements are made at a single wavelength and a birefringence picture is made of the sample. Current spatially resolved measurements have been made at a resolution of approximately 40 microm. Four samples have been examined with this instrument: (1) a mica plate, (2) a Polaroid polarizer, and (3) two quartz plates.
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Lowndes DH, Geohegan DB, Puretzky AA, Norton DP, Rouleau CM. Synthesis of Novel Thin-Film Materials by Pulsed Laser Deposition. Science 1996; 273:898-903. [PMID: 8688065 DOI: 10.1126/science.273.5277.898] [Citation(s) in RCA: 499] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Pulsed laser deposition (PLD) is a conceptually and experimentally simple yet highly versatile tool for thin-film and multilayer research. Its advantages for the film growth of oxides and other chemically complex materials include stoichiometric transfer, growth from an energetic beam, reactive deposition, and inherent simplicity for the growth of multilayered structures. With the use of PLD, artificially layered materials and metastable phases have been created and their properties varied by control of the layer thicknesses. In situ monitoring techniques have provided information about the role of energetic species in the formation of ultrahard phases and in the doping of semiconductors. Cluster-assembled nanocrystalline and composite films offer opportunities to control and produce new combinations of properties with PLD.
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