npj：绝缘体研究发现新物相

锆酸锶是电绝缘体，因其有较大的介电常数而在半导体技术领域有很大应用潜力。它具有钙钛矿结构，受热后原子结构在不同的温度发生相应的改变。但相变带来什么效应还处于争论之中。来自印度CSIR国家物理实验室的Ashok Kumar及其同事观察到锆酸锶在650 K的相变。他们通过测定与原子振动相关的拉曼光谱和介电光谱，研究了锆酸锶的结构。从光谱结果中确定了锆酸锶的三个异常特征，并由此推断了一个新相变的存在，确定了一种具有意外原子排列结构的材料，有望应用于电子器件。该文近期发表于npj Computational Materials 3: 2 (2017), 标题与摘要如下，点击阅读原文可以获取论文PDF。

We present detailed Raman studies of SrZrO3 (SZO) that show three anomalies in Raman modes: One has a small jump in frequency ω, one has its intensity vanish, and a third has a sharp change in temperature derivative dω(T)/dT from flat below T = 600 K to a Curie–Weiss dependence above 600 K with extrapolation to zero frequency at the known transition temperature T = 970 K, thereby proving the latter to be displacive. In addition, the P4mm ferroelectric phase predicted at high stresses has preliminary support from polarization-voltage experiments. The inference of a new transition in the temperature region 600–650 K is in disagreement with neutron studies. Comparisons are given for family member SrSnO3 and SrHfO3, and we discuss the different conclusions of Kennedy and Knight. We show that a known transition in SrHfO3 is also displacive with a well-behaved soft mode.