"Test of the Dynamic-Domain and Critical Scattering Hypotheses in Cubic Methylammonium Lead Triiodide"

Nicholas J. Weadock: Peter M. Gehring , Aryeh Gold-Parker, Ian C. Smith, Hemamala I. Karunadasa, and Michael F. Toney; Physical Review Letters, 08/10/20.

Additional Authors: Peter M. Gehring , Aryeh Gold-Parker, Ian C. Smith, Hemamala I. Karunadasa, and Michael F. Toney

Abstract:

We investigate the hypothesis of dynamic tetragonal domains occurring in cubic CH3NH3PbI3using high-resolution neutron spectroscopy to study a fully deuterated single crystal. The R-point scattering above the 327.5 K cubic-tetragonal phase transition is always resolution limited in energy and therefore inconsistent with dynamic-domain predictions. This behavior is instead consistent with the central peak phenomenon observed in other perovskites. The scattering may originate from small, static, tetragonal-phase domains nucleating about crystal defects, and the temperature dependence demonstrates the transition is first order.