X-Ray Investigation of the High Temperature Structure of (CH₃)₃NHCdCl₃

Abstract

The structural phase transitions in a linear chain compound (CH₃)₃NHCdCl₃ were investigated by an X-ray photographic method. It was found that the high temperature phase above 374 K belongs to the orthorhombic Pbnm (Z=8) rather than to the hexagonal P6₃/m (Z=6) which was proposed by Chapuis and Zuniga. The structure of this high temperature phase was argued to be characterized by an orientationally disordered state of the trimethyl ammonium ions. An analogy to the triangular Ising lattice is also refered.