Crystal structure and phase transitions in the new crystals of [(CH3)2NH2]2CuCl4[(CH3)2NH2]Cl

Crystals grown from a solution of dimethylammonium and copper chlorides are studied using electron paramagnetic resonance (EPR) and X-ray diffraction. The dielectric properties of the crystals grown are measured. It is established that the crystals have the composition [(CH3)(2)NH2](2)CUCl4[(CH3)(2)NH2]Cl and, in phase I at room temperature, are described by the orthorhombic space group Pna2(1) with the unit cell parameters a = 11.338 Angstrom, b = 9.981 Angstrom, and c = 15.675 Angstrom. At temperatures of 279 K and 253 K, the crystals undergo jump-wise phase transitions into the incommensurate modulated ferroelectric phase 11 and commensurate modulated phase III, respectively. (C) 2004 MAIK "Nauka/Interperiodica".