What makes the difference in perovskite titanates?

作者：Bussmann Holder Annette^*; Roleder Krystian; Ko Jae Hyeon

来源：Journal of Physics and Chemistry of Solids, 2018, 117: 148-157.

DOI：10.1016/j.jpcs.2018.02.025

• Perovsldtes
• Phase transitions
• Precursor effects
• Ferroelectricity

We have investigated in detail the lattice dynamics of five different perovskite titanates ATiO(3) (A = Ca, Sr, Ba, Pb, Eu) where the A sites are occupied by +2 ions. In spite of the largely ionic character of these ions, the properties of these compounds differ substantially. They range from order/disorder like, to displacive ferroelectric, quantum paraelectric, and antiferromagnetic. All compounds crystallize in the cubic structure at high temperature and undergo structural phase transitions to tetragonal symmetry, partly followed by further transitions to lower symmetries. Since the TiO6 moiety is the essential electronic and structural unit, the question arises, what makes the significant difference between them. It is shown that the lattice dynamics of these compounds are very different, and that mode-mode coupling effects give rise to many distinct properties. In addition, the oxygen ion nonlinear polarizability plays a key role since it dominates the anharmonicity of these perovskites and determines the structural instability.

• 出版日期2018-6