Mishra Sanjay Kumar, Ranjan Rajeev, Pandey Dhananjai, Ranson Pierre, Ouillon Robert, Pinan-Lucarre Jean-Paul, Pruzan Philippe
School of Materials Science and Technology, Institute of Technology, Banaras Hindu University, Varanasi-221005, India.
J Phys Condens Matter. 2006 Feb 15;18(6):1899-912. doi: 10.1088/0953-8984/18/6/007. Epub 2006 Jan 24.
The phase transition behaviour of two 'nearly cubic' compositions, x = 0.40 and 0.43, of Sr(1-x)Ca(x)TiO(3), representative of Pbnm and Pbcm space group structures, has been investigated using temperature dependent dielectric, x-ray diffraction and Raman scattering techniques. For x = 0.40, a first order antiferroelectric phase transition occurs around 364 K followed by an antiferrodistortive phase transition involving the R point ([Formula: see text]) instability at ∼800 K. For x = 0.43, on the other hand, there is no antiferroelectric phase transition. Instead, two antiferrodistortive transitions around 463 and 850 K linked with the M ([Formula: see text]) and R ([Formula: see text]) point instabilities, respectively, are observed. Both the compositions also exhibit qualitatively different types of phase transitions below room temperature. Evidence for a new phase transition at low temperatures is presented for x = 0.43.
利用与温度相关的介电、X射线衍射和拉曼散射技术，对具有代表性的Pbnm和Pbcm空间群结构的两种“近似立方”成分（x = 0.40和0.43）的Sr(1-x)Ca(x)TiO(3)的相变行为进行了研究。对于x = 0.40，在约364 K发生一级反铁电相变，随后在约800 K发生涉及R点（[公式：见正文]）不稳定性的反铁畸变相变。另一方面，对于x = 0.43，不存在反铁电相变。相反，观察到分别在约463 K和850 K发生的与M（[公式：见正文]）和R（[公式：见正文]）点不稳定性相关的两个反铁畸变相变。两种成分在室温以下也表现出性质不同的相变类型。给出了x = 0.43在低温下发生新相变的证据。
