EPR zero-field splitting parameters and structural distortion study of Mn2+-doped (CH3)4NCdCl3 crystal in high-temperature phases

The EPR zero-field splitting parameters and structural distortion of Mn2+-doped (CH3)(4)NCdCl3 crystal in high-temperature phases have been studied by diagonalizing the complete energy matrices. The zero-field splitting parameters D and (a - F) are demonstrated to be negative and positive, respectively, and obtain a reasonable explanation together. Simultaneously, the distortion magnitude of local lattice structure around the Mn2+ ion in this. crystal is determined, namely, Delta R = -0.13 angstrom and Delta theta = 2.975 degrees for T = 124 K; Delta R = -0.12 angstrom and Delta theta = 2.610 degrees for T = 297 K; Delta R = -0.26 angstrom and Delta O = 2.870 degrees for T = 573 K. From the structural distortion, we deduce that a new structural phase transition should occur to the (CH3)(4)NCdCl3 crystal at temperatures ranging from 297 to 573 K. This is also in agreement with recent differential scanning calorimetric measurements. (c) 2006 Elsevier B.V. All rights reserved.