Dynamical tilting in halide perovskites

TL;DR

This paper explores the concept of dynamical octahedral tilting in halide perovskites, deriving all possible space groups for such dynamic structures and analyzing their impact on physical properties.

Contribution

It extends existing static tilting space group tables to include dynamical tilting, providing a comprehensive framework for understanding dynamic disorder in perovskites.

Findings

Dynamical tilting is ubiquitous in halide perovskites.

Derived new space groups for dynamically tilted perovskites.

Discussed potential effects of dynamic disorder on material properties.

Abstract

Naturals and synthetic perovskites are widely used functional materials thanks to their particular physical properties, such as superconductivity, ferroelectricity and photo-activity. Many of these properties are related to static or dynamic motion of octahedral units; Yet a full understanding of the relationships between perovskite crystal structure, chemical bonding and physical properties is currently missing. Several studies indicate the existence of dynamic disorder generated by anharmonic motion of octahedral units e.g. in halide perovskite structures. In this work, we derive all possible space groups for simple perovskites $\rm ABX_3$ with dynamical octahedral tilting. The derived space groups extend the well established space group tables for static tiltings by [Glazer, A. Acta Cryst. B 1972, 28, 3384-3392; Aleksandrov, K. Ferroelectrics 1976, 24, 801-805; Howard, C.J., Stokes, H.T. Acta Cryst. B 1998, 54, 782-789]. We demonstrate ubiquity of dynamical tilting by analysing the structural data for perovskites reported in recent scientific publications and discuss the signature of dynamic tilting in the corresponding structures. Finally, we discuss the possible influence of dynamic disorder on the physical properties of halide perovskites.