Relaxor Ferroelectric and Proton Glass Systems

弛豫铁电和质子玻璃系统

• 批准号: 9520251
• 负责人: V. Hugo Schmidt
• 金额: $ 25万
• 依托单位: Montana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-11-01 至 1998-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9520251&HistoricalAwards=false
• 关键词: Relaxor; Ferroelectric; Proton; Glass; Systems

9520251 H. Schmidt The PI will investigate properties of partially disordered materials in particular of proton glass crystals and relaxor ferroelectrics. A broad range of measurements, such as dielectric spectroscopy from 1 mHz to 1 GHz, third-order dielectric permittivity, hysterisis loops, field heating and zero-field heating, and Brillouin scattering will be conducted at Montana State. Neutron scattering and diffraction will be carried out at Brookhaven National Laboratory. Phenomena to be investigated include smearing of the phase transition and clustering in relaxor ferroelectrics, nonergodic behavior, phase coexistence and proton tunneling in proton glasses. Proton glass results will be interpreted in terms of the bound charge semiconductor model and a phonon-assisted tunneling model. A diffusion-barrier-limited conductivity model and other appropriate models will be used to interpret the relaxor ferroelectric behavior. Monte Carlo simulations of proton glass behavior will also be performed. %%% Partially disordered crystalline materials, in which atoms of one type are replaced by those of another type, at random sites in the crystal will be investigated. The focus is on materials which show unusual response to electric fields. These include proton glasses, mixtures of ferroelectric crystals which polarize spontaneously and antiferroelectrics which consist of oppositely polarized interlocking parts. Relaxor ferroelectrics which have pronounced mechanical response to an electric field, and are beginning to find application as sensors and actuators will also be studied. The objective is to understand the fundamental properties, including the response to electromagnetic fields of very low to very high frequencies, the effects of heating and cooling, and the structure of these materials. Attempts will be made to improve upon existing conceptual and mathemat ical models of these materials. ***

9520251 H施密特 PI将研究部分无序材料的性质，特别是质子玻璃晶体和弛豫铁电体。 将在蒙大拿州进行广泛的测量，如1兆赫至1千兆赫的介电谱、三阶介电常数、磁滞回线、场加热和零场加热以及布里渊散射。中子散射和衍射将在布鲁克海文国家实验室进行。 所要研究的现象包括弛豫铁电体中相变的拖尾和团簇，质子玻璃中的非遍历行为，相共存和质子隧穿。质子玻璃的结果将被解释的束缚电荷半导体模型和声子辅助 隧穿 模型 一 扩散势垒限制电导率模型和其他合适的模型将被用来解释弛豫铁电行为。质子玻璃行为的蒙特卡罗模拟也将进行。 部分无序的晶体材料，其中一种类型的原子被另一种类型的原子取代，在晶体中的随机位置将被研究。重点是对电场表现出不寻常反应的材料。这些包括质子玻璃，铁电玻璃和铁电玻璃的混合物， 晶体 这 偏振 自发 以及由相反极化的互锁部分组成的反铁电体。 弛豫铁电体， 对电场的机械响应，并开始发现作为传感器和致动器的应用也将被研究。其目的是了解基本性质，包括对极低到极高频率的电磁场的响应，加热和冷却的影响以及这些材料的结构。 将尝试改进这些材料的现有概念和物理模型。 ***