Whittle Thomas A, Brant William R, Hester James R, Gu Qinfen, Schmid Siegbert
School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.
Dalton Trans. 2017 Jun 6;46(22):7253-7260. doi: 10.1039/c7dt00352h.
The structures across the SrTiZrNbO, 0 ≤ x ≤ 0.6, defect perovskite series were investigated using complementary synchrotron X-ray and neutron powder diffraction data. The locations of second order compositional and temperature dependent phase transitions between the high symmetry cubic Pm3[combining macron]m phase and the lower symmetry tetragonal I4/mcm phase were determined. Deviation of the oxygen x coordinate from the high symmetry value and the B-O-B bond angle from 180° as well as the tetragonal strain squared were each found to be suitable order parameters to monitor the transitions. Tolerance factor calculations confirmed that these A-site deficient perovskites retain a higher symmetry to a lower value than their fully occupied counterparts. Therefore, adjusting vacancy concentrations can be employed as a general strategy to design compounds with specifically tailored phase transition temperatures.
利用同步加速器X射线和中子粉末衍射互补数据，对0≤x≤0.6的SrTiZrNbO缺陷钙钛矿系列结构进行了研究。确定了高对称立方Pm3[上加一横]m相和低对称四方I4/mcm相之间二阶成分和温度相关相变的位置。发现氧x坐标偏离高对称值、B - O - B键角偏离180°以及四方应变平方均是监测相变的合适序参量。容差因子计算证实，这些A位缺陷钙钛矿比其完全占据的对应物在更低的值时仍保持更高的对称性。因此，调整空位浓度可作为设计具有特定相变温度的化合物的通用策略。
