A theoretical investigation of Ti3+ in yttrium borophosphate glass materials: Local structures and optical properties

Abstract Local structure and g factors for (20-x)CaF2-10CaO-5Y2O3-10B2O3-55P2O5: xTiO2(x = 0.2, 0.4, 0.6, 0.8 and 1.0 mol%) glasses are theoretically studied by using the perturbation formulae for a tetragonally elongated octahedral 3d1 cluster. Six coordinated [TiO6]9‒ and five coordinated [TiO5]7‒ clusters are evaluated in view of the Jahn-Teller effect and the charge compensation of impurity Ti3+ for host Ti4+. d -d transition bands of E2 (2B2g→2A1g) and E3 (2B2g→2B1g) of the [TiO5]7‒ cluster is obtained with the piecewise linear fitting function of x. The microscopic mechanisms of the varying rules of relevant quantities g//, E2 and N with x are related with NBO. The role of various TiO2 concentrations in local structure and optical spectra is also comprehensively studied from the local optical basicity Λloc, which can represent the local environment and covalency of the Ti3+ center.