Complex Perovskites: Chemical & Structural Complexity as a Route to New Functional Materials

技术概述：众所周知，增加钙钛矿结构组成复杂性的化学取代会产生在更简单的材料中无法实现的性能。然而，随着组成复杂性的增加，需要详细了解驱动原子组装成均相单相材料的成键相互作用，以便合理地探讨此类材料的合成和设计。拟议的研究包括合成新的钙钛矿，使用先进的结构表征工具，以及研究这些材料的性能测量。具体的研究目标包括：(1)通过同时排列A位和B位的阳离子阵列，合成和表征具有介电、磁和离子导电性能的新型钙钛矿材料。(2)八面体倾斜破坏了八面体骨架的角共享连接性的钙钛矿研究。(3)氟氧双钙钛矿的相变研究，结合阳离子键取向控制阴离子氟氧多面体的取向有序性。变温拉曼光谱研究将用于跟踪局部和远程结构随温度或组成变化而发生的变化。人们期待具有诱人的介电、磁、非线性光学和电学性能的新材料。非技术概述：钙钛矿材料在许多重要技术中发挥着核心作用，其中包括：电子应用的介电材料，电池和燃料电池的离子导体，超导和磁阻等。这笔赠款将促进我们对如何控制元素的原子尺度有序的理解，以生产这些重要技术所需的新材料。这项研究涉及与澳大利亚和西班牙的国际知名电子显微镜中心的合作。为了传播这一知识，将开发基于网络的资源，这些资源将对几个学科的教学和研究产生积极影响。将创建、实施和传播一个教授X射线粉末衍射和晶体堆积力原理的高级实验室实验。最后，该项目将为研究生和本科生提供学习现代材料化学研究所需技能的重要机会。学生将通过这个项目支持的国内和国际合作建立重要的联系。

TECHNICAL SUMMARY: Chemical substitutions that increase the compositional complexity of the perovskite structure are known to give rise to properties that cannot be realized in simpler materials. However, as the compositional complexity increases detailed knowledge of the bonding interactions that drive atoms to assemble into homogeneous single phase materials is needed to rationally approach the synthesis and design of such materials. The proposed research involves synthesis of new perovskites and the use of advanced structural characterization tools, and property measurements to study these materials. The specific research objectives involve: (1) Synthesis and characterization of new perovskites with useful dielectric, magnetic and ionic conduction properties by simultaneously ordering A- and B-site cation arrays. (2) Studies of perovskites where octahedral tilting disrupts the corner sharing connectivity of the octahedral framework. (3) Studies of phase transitions in oxyfluoride double perovskite, coupled with use of cation bonding preferences to control the orientational ordering of anionic oxyfluoride polyhedra. Variable temperature Raman spectroscopy studies will be used to follow changes in local and long range structure that occur in response to changes in temperature or composition. New materials with attractive dielectric, magnetic, nonlinear optical and electrical properties are anticipated. NON-TECHNICAL SUMMARY: Perovskite materials play a central role in many important technologies including: dielectric materials for electronic applications, ion conductors for batteries and fuel cells, superconductivity and magnetoresistance to name a few. This grant will advance our understanding of how to control atomic scale ordering of elements to produce new materials for these important technologies. The research involves collaborations with internationally renowned electron microscopy centers in Australia and Spain. To disseminate this knowledge Web based resources will be developed that will positively impact teaching and research across several disciplines. An upper level laboratory experiment that teaches the principles of X-ray powder diffraction and crystal packing forces will be created, implemented and disseminated. Finally the project will provide important opportunities for graduate and undergraduate students to learn skills that are needed for modern materials chemistry research. Students will create important contacts through national and international collaborations supported by this project.