Theoretical Studies of the Spin Hamiltonian Parameters and Local Distortions for Cu2+in Alkaline Earth Lead Zinc Phosphate Glasses

The spin Hamiltonian parameters and local structures are theoretically studied for Cu2+-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d9cluster. The relative elongation ratios are found to be ρ≈3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dqand orbital reduction factor kfrom Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu2+–O2−electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dqand the next highest kamong the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Ba<Ca<Sr) of ρis largely due to the decreasing crystal-field strength Dqand hence the decreasing force constant of the Cu2+–O2−bonds. The present studies would be helpful to understand local structures and the influences on the optical properties of RPPZ glasses containing copper dopants.