Materials World Network: Atomistic Nature of the Physical Processes in Relaxors

材料世界网络：弛豫器中物理过程的原子性质

• 批准号: 0602876
• 负责人: Takeshi Egami
• 金额: $ 26.4万
• 依托单位: University of Tennessee Knoxville
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0602876&HistoricalAwards=false
• 关键词: Materials; World; Network; Atomistic; Nature

The project entails cooperative research of complex ferroelectric oxides between the group from the University of Tennessee at Knoxville, USA, and the group from A. F. Ioffe Physico-Technical Institute, Russian Academy of Science, St. Petersburg, Russia. It addresses some of the most important unsolved and current problems in the field of ferroelectric materials. In particular it aims at 1) identification of the atomistic origin of a relaxor behavior in Pb-based magnesium-niobate perovskite, 2) examination of dynamic and structural instabilities leading to phase transitions in Na-based niobate perovskite, and 3) elucidation of the structural factors resulting in a relaxor transition in solid solutions of Na niobate perovskite. Advancing this knowledge would greatly facilitate development of lead-free relaxor piezoelectric materials. The main reason hindering the understanding of the atomistic mechanism of the relaxor behavior is strong displacive and chemical disorder in the local atomic structure which frustrates conventional structural and dynamical studies. The project will leverage complementary research expertise of the two groups in applying neutron and X-ray scattering to study lattice dynamics and local atomic structure of the complex ferroelectrics. The US group will focus on powder samples and local structural methods whereas Russian group will be additionally examining single crystals. The local atomic structure will be studied by the atomic pair distribution function method that has proven to be very effective in determination of atomic displacements and disorder. Complementary detailed studies of lattice dynamics (phonons) in single crystals will be performed by the Russian researchers. The emphasis will be placed on understanding physics behind the giant dielectric response of lead-free relaxor-like solid solutions and critical dynamics and structural instabilities. The project will have broad impact for society and industry by advancing knowledge for the development of environmentally benign piezoelectric ceramics. Traditional materials, based on lead can create health hazards. The results will be quickly disseminated to contribute to education and stimulate research and development. The collaborative framework of this project will allow training of graduate and undergraduate student in new experimental techniques and involve them into science and technology of ferroelectric materials. This approach will enhance quality of education and promote new ideas through the exchange visits and collaborative experiments.

该项目包括美国田纳西大学诺克斯维尔分校的研究组和美国A. F.俄罗斯科学院Ioffe物理技术研究所，俄罗斯彼得堡。它解决了铁电材料领域中一些最重要的未解决的和当前的问题。 特别地，其目的在于1）识别Pb基镁-钙钛矿中弛豫行为的原子起源，2）检查导致Na基镁-钙钛矿中相变的动态和结构不稳定性，以及3）阐明导致Na-钙钛矿固溶体中弛豫转变的结构因素。推进这方面的知识将大大促进无铅弛豫压电材料的发展。局域原子结构中强烈的位移无序和化学无序阻碍了传统的结构和动力学研究，是阻碍人们理解弛豫行为的原子机制的主要原因。该项目将利用两个小组在应用中子和X射线散射研究复杂铁电体的晶格动力学和局部原子结构方面的互补研究专长。美国团队将专注于粉末样品和局部结构方法，而俄罗斯团队将额外检查单晶。局部原子结构将通过原子对分布函数方法进行研究，该方法已被证明在确定原子位移和无序方面非常有效。俄罗斯研究人员将对单晶中的晶格动力学（声子）进行补充详细研究。重点将放在理解物理背后的无铅弛豫型固溶体和临界动力学和结构不稳定性的巨大介电响应。 该项目将对社会和工业产生广泛的影响，促进对环境友好的压电陶瓷的发展。基于铅的传统材料会造成健康危害。研究结果将迅速传播，以促进教育和促进研究与发展。该项目的合作框架将允许研究生和本科生在新的实验技术的培训，并让他们参与铁电材料的科学和技术。这一方法将通过互访和合作实验提高教育质量，并促进新思想。