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首页> 外文会议>Advances in X-ray analysis (ICDD2001) >USE OF IN-SITU XRD TO DEVELOP CONDUCTING CERAMICS WITH THE AURIVILLIUS CRYSTAL STRUCTURE
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USE OF IN-SITU XRD TO DEVELOP CONDUCTING CERAMICS WITH THE AURIVILLIUS CRYSTAL STRUCTURE

机译：使用原位XRD开发具有声晶体结构的导电陶瓷

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In-situ X-ray diffraction was used to study structural transformations in several n=3 Aurivillius-type phases: Bi_4Ti_3O_(12), Bi_2La_2Ti_3O_(12), Bi_2Sr_2Nb_2TiO_(12), Bi_2Sr_2Nb_2A1O_(11.5) and Bi_2Sr_2Nb_2GaO_(11.5). Order-disorder transformations have been linked to transitions to fast ion conduction in certain oxygen-deficient phases, such as Bi_2Sr_2Nb_2AlO_(11.5) and Bi_2Sr_2Nb_2GaO_(11.5). Bi_2La_2Ti3O_(12) and Bi_2Sr_2Nb_2TiO_(12) were synthesized and indexed as body-centered tetragonal with 4/mmm Laue symmetry. At room temperature, Bi_4Ti_3O_(12) has an orthorhombic unit cell with space group symmetry B2ab. As previously documented, it transforms to tetragonal above its Curie temperature of 675 C. Indexing of XRD data collected for this study indicates the high temperature phase is body-centered tetragonal with 4/mmm Laue symmetry, similar to the structures of Bi_2La_2Ti_3O_(12) and Bi_2Sr_2Nb_2TiO_(12). None of these phases undergo additional phase transformations up to 1100 C. Both Bi_2Sr_2Nb_2AlO_(11.5) and Bi_2Sr_2Nb_2GaO_(11.5) have oxygen-deficient perovskite-layers, with either primitive tetragonal or orthorhombic unit cells at room temperature. Both materials undergo multiple phase transformations. Above 875 C, the unit cells are similar to those of the non-oxygen deficient n=3 Aurivillius-type phases, being body-centered tetragonal with 4/mmm Laue symmetry. This behavior agrees with the expectations for oxygen-vacancy order-disorder transformations. The intermediate phases are not yet fully understood: they may be associated with partial disordering of oxygen vacancies or with a ferroelectric transition.
机译：原位X射线衍射用于研究n = 3个Aurivillius型相中的结构转变：Bi_4Ti_3O_（12），Bi_2La_2Ti_3O_（12），Bi_2Sr_2Nb_2TiO_（12），Bi_2Sr_2Nb_2A1O_（11.5）和Bi_2Sr_2Nb_2GaO_（1）。在某些缺氧相中，例如Bi_2Sr_2Nb_2AlO_（11.5）和Bi_2Sr_2Nb_2GaO_（11.5），有序无序转换与快速离子传导的跃迁有关。合成了Bi_2La_2Ti3O_（12）和Bi_2Sr_2Nb_2TiO_（12），并以劳厄对称性为4 / mm的指数定为体心四边形。在室温下，Bi_4Ti_3O_（12）的正交晶胞具有空间群对称性B2ab。如先前记录的那样，它在居里温度675 C之上转变为四方晶。为该研究收集的XRD数据索引表明，高温相是体心四方的Laue对称性，类似于Bi_2La_2Ti_3O_（12）的结构和Bi_2Sr_2Nb_2TiO_（12）。这些相都不会在1100°C以下进行任何相变。Bi_2Sr_2Nb_2AlO_（11.5）和Bi_2Sr_2Nb_2GaO_（11.5）都具有缺氧钙钛矿层，在室温下具有原始的四方晶系或正交晶系。两种材料都经历了多个相变。在875 C以上，单位晶胞类似于非缺氧n = 3 Aurivillius型相的晶胞，其体心四边形具有4 / mmm Laue对称性。这种行为符合对氧空位有序-无序转化的期望。中间阶段尚未完全理解：它们可能与氧空位的部分紊乱或铁电转变有关。

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