Order–Disorder Structural Phase Transitions in Alkali Perchlorates

Order–disorder structural phase transitions in alkali perchlorates MClO4 (M=Na, K, Rb, Cs) are investigated using molecular dynamics simulation. The potentials in the simulations are based on the Gordon–Kim modified electron gas formalism extended to molecular ions. The simulations yield first-order phase transitions in perchlorates from low temperature orthorhombic structures to high temperature cubic NaCl structures. The perchlorate ions are found to be orientational disordered in the high temperature phases.