Order-Disorder Phase Transitions in KNO₂ , CsNO₂, and TlNO₂ crystals: A molecular dynamics study

Authors

Chun-Gang Duan, University of Nebraska at OmahaFollow
Wai-Ning Mei, University of Nebraska at OmahaFollow
R. W. Smith, University of Nebraska at OmahaFollow
Jianjun Liu, University of Nebraska-Lincoln
M. M. Ossowski, University of Nebraska-Lincoln
John R. Hardy, University of Nebraska-LincolnFollow

Date of this Version

2001

Comments

Published in Phys. Rev. B VOLUME 63, 144105. Copyright © 2001 The American Physical Society. Used by permission.

Abstract

The order-disorder phase transitions of KNO₂ , CsNO₂, and TlNO₂ have been studied using parameter-free molecular dynamics simulation. It is found that the phase transitions in nitrites investigated are driven by the rotations of the NO₂^- ions about different axes together with displacements of cations and anions. We successfully reproduce the high-temperature phases of these nitrites, i.e., the NaCl-like structure for KNO₂ and CsCl-like structure for Cs(Tl)NO₂. Based on the investigation of the radial distribution function of the cations and anions, we explain why KNO₂ and Cs(Tl)NO₂ form quite different low-temperature phases.