High pressure-induced structural transformations in lead-based perovskite type relaxor ferroelectrics

铅基钙钛矿型弛豫铁电体的高压诱导结构转变

• 批准号: 24880926
• 负责人: Professorin Dr. Boriana Mihailova
• 金额: --
• 依托单位: Mineralogisch-Petrographisches Institut (MPI)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/24880926?language=en
• 关键词: pressure; induced; structural; transformations; lead

Relaxor ferroelectrics are functional materials with multiple applications due to their extraordinary dielectric properties, piezoelectric response and electrooptical coefficients. The unique macroproperties of these materials are related to their rather complex nanoscale structure, which deviates substantially from the average structure detectable by diffraction analysis. In order to better understand the interplay between the local structural phenomena and relaxor behaviour we are going to apply diffraction and phonon spectroscopic methods under in situ p/T conditions. Pressure will help to elucidate the preferential local atomic ordering, since it affects mainly the short-range interatomic interactions. A major group of relaxors are lead-based complex perovskites. This project aims to study (i) the local structure of two compounds with equal stoichiometry and ionic radii, PbSc0.5Nb0.5O3 and PbSc0.5Ta0.5O3, under high p/T conditions in order to analyse elastic tension-favourite atomic clustering, pressure-induced phase transformations and renormalization phenomena in relaxors of type PbB¿0.5B¿0.5O3; (ii) A-doped and B¿-cation mixed PbSc0.5Nb0.5O3 and PbSc0.5Ta0.5O3 in order to analyse the compositional renormalization of elastic field-induced structural transformations. The high-pressure Raman scattering and X-ray diffraction experiments will be performed on single crystals, not on ceramics, to achieve correct differentiation of the local structural phenomena occurring in the crystalline bulk. Syntheses under extremely high p/T will be performed to tailor novel relaxors.

弛豫铁电体由于其非凡的介电性能、压电响应和电光系数而成为具有多种应用的功能材料。这些材料独特的宏观性能与其相当复杂的纳米级结构有关，该结构大大偏离衍射分析可检测到的平均结构。为了更好地理解局部结构现象和弛豫行为之间的相互作用，我们将在原位 p/T 条件下应用衍射和声子光谱方法。压力将有助于阐明优先局部原子排序，因为它主要影响短程原子间相互作用。主要的弛豫剂是铅基复合钙钛矿。该项目旨在研究 (i) 在高 p/T 条件下具有相同化学计量和离子半径的两种化合物 PbSc0.5Nb0.5O3 和 PbSc0.5Ta0.5O3 的局域结构，以分析松驰剂中的弹性张力偏好原子簇、压力诱导相变和重正化现象 PbB?0.5B?0.5O3; (ii) A 掺杂和 B¿ 阳离子混合 PbSc0.5Nb0.5O3 和 PbSc0.5Ta0.5O3，以分析弹性场引起的结构转变的成分重正化。高压拉曼散射和 X 射线衍射实验将在单晶而不是陶瓷上进行，以实现对晶体块中发生的局部结构现象的正确区分。将在极高的 p/T 下进行合成，以定制新型弛豫剂。