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Showing 1 to 20 of 29 for “"relaxor"”.
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Dielectric noise spectroscopy of relaxor ferroelectrics
… answer one simple question: are the dynamics of relaxor ferroelectrics cooperative? To accomplish this task, we have developed a promising new technique that is excellent at sorting out the internal dynamics of high dielectric materials. Specifically we have examined the dynamics of the relaxor …
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Aging and Barkhausen noise in the relaxor ferroelectrics
"Relaxor ferroelectrics are disordered crystalline materials whose polar order is limited to mesoscopic-scaled nanodomains. There is no ferroelectric phase transition, but a faster than Arrhenius cooperative freezing into a glassy relaxor regime instead. It is not understood how the random fields …
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Machining induced defects in Relaxor ferroelectric PMN-PT crystals
… piezoelectric and dielectric properties of the relaxor based piezoelectric single crystals (PMN-PT) render them as prime candidates for Navy sonar detectors as well as broad band medical ultrasonic imaging devices. Production of phased array probes utilizing these types of high performance …
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Local symmetry and polarization in relaxor-based ferroelectric crystals
Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2013-05-24T22:02:27Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Kim_KyouHyun.pdf: 4556380 bytes, checksum: 3dac9ee508db17f0bac12ef97b4d87d3 (MD5)
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Structure-property relationships in strontium barium niobate relaxor ferroelectrics
… response found for Pb-based perovskite relaxors. The dielectric absorption of SBN was also found to be much stronger along the c-axis than along any other orientation. Investigations of the temperature dependence of the high-field polarization behavior found that a square-to-slim loop …
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Development of phonon-polarization THz spectroscopy, and the investigation of relaxor ferroelectrics
… first THz frequency dielectric measurements of a relaxor ferroelectric crystal, in particular KTao0.982Nb0.018O3 (KTN 1.8). THz spectroscopy has emerged as an important probe for a wide variety of systems with the development of pulsed THz radiation sources and time-domain detection methods. Four …
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Synchrotron X -Ray Scattering Studies of Local Fluctuations in Lead Magnesium Niobate Relaxor Ferroelectrics
Temperature dependent synchrotron x-ray diffraction studies of PMN-PT single crystals confirmed the existence of anti-ferroelectric fluctuations produced by correlated atomic displacements using state-of-the art experimental facilities. Detailed quantitative analysis of the corresponding …
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Sol-gel processing, perovskite phase development and properties of relaxor-based thin layer ferroelectrics
This thesis reports on the preparation and properties of thin layer ceramics in the Pb ((Zn$\sb{1/3}$Nb$\sb{2/3})\sb{\rm 1-x}$Ti$\sb{\rm x}$) O$\sb3$ (PZNT) and Pb ((Mg$\sb{1/3}$Nb$\sb{2/3})\sb{\rm 1-x}$Ti$\sb{\rm x}$) O$\sb3$ (PMNT) systems for capacitor and ferroelectric applications. Sol-gel …
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Experimental investigation and modeling of the electrostrictive relaxor ferroelectric lead magnesium niobate-lead titinate
… behaviors of the electrostrictive relaxor ferroelectric lead magnesium niobate-lead titinate (PMN-PT) are experimentally characterized and phenomenologically modeled. The dependencies of PMN-PT electromechanical transduction on temperature and frequency, characteristics of relaxor …
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The Freezing Mechanisms of Perovskite Relaxor Ferroelectrics and the Thermodynamic Stability of their Ferroelectric States
Relaxor ferroelectrics are disordered crystalline materials that have short-range ferroelectric order, known as polar nanoregions. These materials do not exhibit a ferroelectric phase transition at zero field, but rather enter a glassy-like relaxor regime. The source of the glassy freezing and the …
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Development of MRI-compatible Transducer Array for Focused Ultrasound Surgery: : The Use of Relaxor-based Piezocrystals
Focused ultrasound surgery (FUS) is considered as a promising approach for treating cancer and other conditions and is gaining increasing interest. However, the limited availability of experimental ultrasound array sources and multichannel electronics able to drive them hinder the research into FUS …
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Microstructure and Electrical Properties of Mocvd-Derived Perovskite Lead Zirconium(x) Titanium(1-X) Oxygen(3) and Lead (Scandium Tantalum)(1-X) Titanium(x) Oxygen(3) Thin Films on Lanthanum Nickel Oxide Electrode-Buffered Silicon
… PZT thin films, we expanded the work to grow relaxor ferroelectric thin films. Solid solutions of Pb(Sc1/2Ta1/2)1-xTixO 3 (x = 0--0.3) (PSTT) were grown. Phase evolution of the PSTT thin films with respect to the growth conditions, including growth temperature, processing of the bottom …
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Temperature And Pressure Effects On Elastic Properties Of Relaxor Ferroelectrics And Thermoelectrics: A Resonant Ultrasound Spectroscopy Study
Relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) material exhibits exceptional electromechanical properties. The material undergoes a series of structural phase transitions with changes in temperature and the chemical composition. The work covered in this dissertation seek to …
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X-Ray Scattering Study of the Transition Dynamics in Relaxor Ferroelectric Lead (Magnesium(1/3) Niobium(2/3)) Oxygen(3) (Pmn)
Thermal diffuse scattering measurements were performed at several temperatures. A [011] transverse optic soft mode was determined to exist. The temperature dependence of this phonon mode was carefully studied as the transition is approached, and down to 40 K. The q-dependency of the freezing …
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Structure-property correlations in compositionally complex ferroelectrics
… systems: compositionally heterogeneous relaxors and stoichiometry-controlled orthoferrites. Relaxor ferroelectrics show exceptional electromechanical response, energy storage capacity, and electrocaloric properties, finding applications ranging from ultrasound imaging to electrical …
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Bismuto mangano oksido ir giminingos keramikos dielektriniai tyrimai /
… behavior of the ceramic to a ferroelectric relaxor – a broad peak of the real part of dielectric permittivity ε'. In working with the (Bi0.06Na0.94)(Mn0.04Nb0.96)O3 ceramic the same temperature and frequency ranges were studied. It was impossible to univocally determine whether the ceramic …
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Structure-Property Relationship Investigations of Higher and Lower Valent Modified Lead Zirconate Titanate Ceramics
… presence of strong nonlinearities and induced relaxor characteristics under moderate AC drive for lower La-content compositions. TEM investigations demonstrated a breakdown of ferroelectric domains with increasing AC drive, resulting in anomalous AC field effects.
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Polyoxoniobates: How Solution Chemistry Helps to Understand the Solid State
… is proposed for the chemical B-site ordering in relaxor ferroelectric Pb3ZnNb2O9 and Pb3MgNb 2O9. The basis for this model is the imposition of order using a divalent cation nearest-neighbor exclusion algorithm on a random cubic lattice with 2:1 Nb:(Mg/Zn) occupancy. The ordered structure …
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Dipole Ordering or Disordering in Selected Perovskite Ferroelectric Systems
… from a normal ferroelectric to a strongly relaxor system. These transitions were examined using Curie-Weiss and Vogel-Fulcher fitting.
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