• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >The Compositional Dependence of Octahedral Tilting in Orthorhombic and Tetragonal Perovskites
【24h】

The Compositional Dependence of Octahedral Tilting in Orthorhombic and Tetragonal Perovskites

机译：正交晶和四方钙钛矿中八面体倾斜的成分依赖性

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

A new parameterization is defined for the quantitative description of octahedral tilting in orthorhombic and tetragonal perovskites. It contains six parameters, s1, s2, s3, θX, θy and θZ. s1, s2 and s3 refer to the lengths of the lines or 'stalks' joining pairs of opposite octahedral vertices, and θX, θy and θZ to the angles subtended by these stalks with pseudo-cubic axes x, y and z. An equation is derived for the dependence of polyhedral volume ratio, VA/VB> on these parameters: VA/VB = 6cos2θmcosθz-l, where θm = (θX + θy)/2. To a good approximation, lengths s1, s2 and s3 do not affect VA/VB. The validity of this equation is tested by reference to the known crystal structures of 48 ternary oxide and fluoride perovskites, and its versatility demonstrated by application to the structures of some ternary palladium and platinum hydrides. The relationship of the approach to Glazer's system of nomenclature for octahedral tilting in perovskites is considered, in particular concerning the numbers of tilts operative in a given structure. A comparison is also made with the parameterization proposed for octahedral tilting and distortion in rhombohedral perovskites [Thomas & Beitollahi (1994). Acta Cryst. B50, 549-560]. Factors governing the choice of rhombohedral or orthorhombic symmetry are discussed, with the significance of rhombohedral symmetry in obtaining ferroelectric properties brought out. Through the compilation of a table of AO12 and BO6 polyhedral volumes, the prospect is identified of predicting both the degree of octahedral tilting and the likelihood of ferroelectric behaviour for novel, hypothetical oxide compositions.
机译：定义了一种新的参数化方法，用于定量描述正交晶和四方钙钛矿中的八面体倾斜。它包含六个参数s1，s2，s3，θX，θy和θZ。 s1，s2和s3指的是连接成对的八面体顶点对的线或“茎”的长度，θX，θy和θZ代表这些茎与伪立方轴x，y和z对向的角度。对于这些参数，得出了多面体体积比VA / VB>的方程：VA / VB =6cos2θmcosθz-1，其中θm=（θX+θy）/ 2。大致而言，长度s1，s2和s3不会影响VA / VB。参考已知的48种三元氧化物和氟化钙钛矿的晶体结构测试了该方程式的有效性，并通过将其应用于某些三元钯和氢化铂的结构​​证明了其多功能性。考虑钙钛矿中八面体倾斜的方法与Glazer命名系统的关系，特别是在给定结构中有效倾斜的数量方面。还与建议的菱形钙钛矿中八面体倾斜和变形的参数化进行了比较[Thomas＆Beitollahi（1994）。 Acta Cryst。 B50，549-560]。讨论了控制菱面体或斜方对称性选择的因素，并提出了菱面体对称性在获得铁电特性方面的意义。通过汇编AO12和BO6多面体体积表，可以确定预测八面体倾斜程度和新型假设氧化物成分的铁电行为的可能性。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号