Phase transitions in K₂ZnCl₄

Authors

H. M. Lu, Universit y of Nebraska - Lincoln
John R. Hardy, Universit y of Nebraska - LincolnFollow

Date of this Version

1992

Comments

Published in Phys. Rev. B 46, 8582 - 8585 (1992). Copyright © 1992 The American Physical Society. Used by permission.

Abstract

It is shown that the potential-energy surface in K₂ZnCl₄ contains a double-well structure, very similar to some of the other A₂BX₄ compounds (e.g., K₂SeO₄, Rb₂ZnCl₄), except that the double well is much deeper and broader, giving rise to a highly disordered high-temperature phase as observed experimentally. A lattice-dynamics study of the Pna2₁ structure shows an instability with the wave vector q=0.5b^*+(0.5±δ)c^*, providing an explanation to the incommensurate phase transition reported recently.