Refinement of the Crystal Structure of [N(CH₃)₄]₂ZnBr₄ in Connection with Its Phase Transition

Abstract

The crystal structure of [N(CH₃)₄]₂ZnBr₄ was studied at 25°C in the normal phase and 13, 11, 6, 1.5, −10, −40 and −100°C in the ferroelastic phase by single crystal diffractometry. The split-atom method and the significance test showed that the constituent ions are in disorder in the normal phase. In the ferroelastic phase, positional and thermal parameters and occupation probabilities of ions were determined. The structure in the ferroelastic phase is characterized by two kinds of chains composed of ZnBr₄ and N(CH₃)₄-1; one kind of which is along the c-direction, while the other kind is along the a-direction.