Space group and crystal structure of the Perovskite CaTiO₃ from 296 to 1720 K

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• 作者：Roushown Ali and Masatomo Yashima
• 关键词：Crystal structure ; Rietveld method ; Phase transition ; In situ measurements
• 刊名：Journal of Solid State Chemistry
• 出版年：2005
• 期刊代码：130_00224596
• 类别：ch
• 出版时间：2005
• 卷：178
• 期：9
• 页码：2867-2872
• 文件大小：322 K

摘要

The structural phase transitions of the calcium titanate perovskite CaTiO₃ were investigated by the Rietveld analysis of high-temperature neutron and X-ray powder diffraction data in the temperature range of 296–1720 K. The present work demonstrates that the compound exhibits two reversible phase transitions of orthorhombic Pbnm-tetragonal I4/mcm and of I4/mcm-cubic at 1498±25 K and 1634±13 K, respectively. No evidence of Cmcm phase is observed between the Pbnm and I4/mcm structures. The lattice parameters discontinuously change at the Pbnm–I4/mcm transition point, while a continuous change is observed for the transformation. These results indicate that the Pbnm–I4/mcm transition is of first order and that the transformation is of either second or higher order.