Structural Phase Transitions in Zinc(II) Perchlorate Hexahydrate

Phase transitions in zinc perchlorate hexahydrate are studied by X-ray powder diffraction method. Structural changes in the vicinity of transitions detected at 364.5 K and 256.3 K are characterized. At the former the orthorhombic Pmn2₁ phase transforms into the Pmna one (a = 7.812(1), b = 13.518(3) and c = 5.279(1) Å at 348.6 K). The latter involves changes of the orthorhombic unit cell (a = 7.7922(9), b = 13.537(2) and c = 5.0588(6) Å at 251.0 K). Temperature dependence of lattice parameters in the range of 180 to 363.3 K are presented.