Energetics of oxygen-octahedra rotations in perovskite oxides from first principles

作     者：Peng Chen Mathieu N. Grisolia Hong Jian Zhao Otto E. González-Vázquez L. Bellaiche Manuel Bibes Bang-Gui Liu Jorge Íñiguez 

作者机构：Materials Research and Technology Department Luxembourg Institute of Science and Technology (LIST) 5 avenue des Hauts-Fourneaux L-4362 Esch/Alzette Luxembourg Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Science Beijing 100190 China Unité Mixte de Physique CNRS Thales Université Paris Sud Université Paris-Saclay 1 avenue A. Fresnel 91767 Palaiseau France Scientific Computing & Software for Experiments Department Sincrotrone Elettra 34149 Basovizza Trieste Italy Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) Campus UAB 08193 Bellaterra Spain Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2018年第97卷第2期

页      面：024113-024113页

核心收录：

基　　金：ERC Consolidator Mintek European Commission, EC Army Research Office Luxembourg National Research Fund Seventh Framework Programme, FP7, (615759) China Scholarship Council, (201504910652) Aeronautical Science Foundation of China, (11574366) 

主　　题：Crystal structure Ferroelasticity Phase diagrams Structural properties Perovskites Density functional theory 

摘      要：We use first-principles methods to investigate the energetics of oxygen-octahedra rotations in ABO3 perovskite oxides. We focus on the short-period, perfectly antiphase or in-phase, tilt patterns that characterize the structure of most compounds and control their physical (e.g., conductive, magnetic) properties. Based on an analytical form of the relevant potential energy surface, we discuss the conditions for the stability of various polymorphs presenting different rotation patterns, and obtain numerical results for a collection of thirty-five representative materials. Our results reveal the mechanisms responsible for the frequent occurrence of a particular structure that combines antiphase and in-phase rotations, i.e., the orthorhombic Pbnm phase displayed by about half of all perovskite oxides, as well as by many nonoxidic perovskites. In essence, the Pbnm phase benefits from the simultaneous occurrence of antiphase and in-phase tilt patterns that compete with each other, but not as strongly as to be mutually exclusive. We also find that secondary antipolar modes, involving the A cations, contribute to weaken the competition between tilts of different types, and thus play a key role in the stabilization of the Pbnm structure. Our results thus confirm and better explain previous observations for particular compounds in the literature. Interestingly, we also find that strain effects, which are known to be a major factor governing phase competition in related (e.g., ferroelectric) perovskite oxides, play no essential role as regards the relative stability of different rotational polymorphs. Further, we discuss why the Pbnm structure stops being the ground state in two opposite limits—namely, for large and small A cations—showing that very different effects become relevant in each case. Our work thus provides a comprehensive discussion and reference data on these all-important and abundant materials, which will be useful to better understand existing compounds as wel