Lattice distortion and Cd2+ vacancy for CsCdF3:Cr3+ crystals

The quantificational relationship between EPR zero-field splitting parameter D and structure parameters of Cr3+ vacancy centre in CsCdF3:Cr3+ crystals was established according to the superposition model and third-order perturbation theory. The existence of Cd2+ vacancy and the lattice distortion were verified. Meanwhile, F- ion moving toward the central Cr3+ by X-1=0.00291nm, X-2=0.001nm, X-3=0.00262nm was obtained. Good agreement between the theoretical results and the experimental values shows that the assumption of the Cd2+ vacancy and the lattice distortion is reasonable. Although the main of source of the tetragonal crystal field comes from the Cd2+ vacancy caused by the charge compensation, the contribution of the lattice distortion can not be neglected.