Theoretical Temperature-Pressure Phase Diagram for {N(CH₃)₄}₂CuBr₄

Abstract

Theoretical phase diagrams for {N(CH₃)₄}₂CuBr₄ crystal are constructed using the phenomenological approach developed earlier for {N(CH₃)₄}₂MCl₄ family crystals. Expressions for thermodynamic potentials of the phases presented on the experimental phase diagram, and for boundaries between these phases are derived. The theoretical temperature-pressure phase diagram is plotted and is found to be in agreement with the experimental diagram. The approximations and assumptions made when constructing theoretical diagrams are discussed.