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)4NCdCl3 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, ΔR = −0.13 Å and Δθ = 2.975° for T = 124 K; ΔR = −0.12 Å and Δθ = 2.610° for T = 297 K; ΔR = −0.26 Å and Δθ = 2.870° for T = 573 K. From the structural distortion, we deduce that a new structural phase transition should occur to the (CH3)4NCdCl3 crystal at temperatures ranging from 297 to 573 K. This is also in agreement with recent differential scanning calorimetric measurements.