Temperature Variation of the Zero-Field Splitting in CdCl2:Mn2+

The expressions derived previously for the zero-field splitting in trigonal symmetry have been used to study the temperature dependence of the splitting in Cd${\mathrm{Cl}}_2$: ${\mathrm{Mn}}^{2+}$ in the temperature range 20-710°K. It has been assumed that a strictly external point-charge point-multipole model is valid. If one considers, because of the lack of available data on the temperature variation of the lattice parameters, that the $c$ dimension of the hexagonal unit cell of the crystal increases linearly with temperature, it is possible to explain the splitting at temperatures below 300 °K. To interpret the splitting in the entire range of temperature meaningfully, the structure parameters at these temperatures must be known rather accurately.