Resumen de Theoretical studies on the g-factors and the local structure of W^(5+) ions in tungsten phosphate glasses (7 pages)
B.F. Zhang, J.Z. Lin, Y.X. Wang, Y. Zhao, Y. F. Zhang
In this work, we adopt the three-order perturbation formulae for g-factors (g_(‖), g_(⊥)) of d^(1) ions in the octahedral environment to calculate the g-factors of W^(5+) ions in tungsten phosphate glasses containing lithium (P_(2)O_(5)-Li_(2)WO_(4)-Li_(2)O). In the light of the high valence state of the studied W^(5+) centers and hence the strong covalency of the studied octahedral [WO_(6)]^(7−) cluster, we consider the contributions to g-factors from the ligand orbital and spin-orbit (SO) coupling interactions based on the cluster approach. The required tetragonal crystal-field parameters are calculated from the local structure of W^(5+) ions based on the superposition model. According to the theoretical calculations, we find that the octahedral [WO_(6)]^(7−) clusters possess the tetragonally compressed distortion with a shorter W-O bond length (≈ 1.54 Å) anda longer one (≈ 2.26 Å) along C_(4) axis and four normal W-O bond length (≈ 1.94 Å) in the perpendicular plane, which infers that the W^(5+) ions are in the form of tungstyl ions (i.e., WO^(3+)). Based on the local structural data, the theoretical values of g_(‖) and g_(⊥) agree well with the experimental values.
