Vol. 38, Issue 1, pp. 189-202 (2008)

Abstract

Optical absorption and luminescence spectra as well as luminescence kinetics of the Nd³⁺ centres in glasses with Ca₃Ga₂Ge₃O₁₂:Nd composition, containing 0.2 and 1.0 wt% of the Nd₂O₃ were presented and analysed. The oscillator strengths and phenomenological intensity parameters Ω_t (Ω₂, Ω₄, and Ω₆) were obtained using standard Judd–Ofelt theory. Calculated Ω_t parameters, radiative transitions rates, branching ratios and radiative lifetime for Nd³⁺ centres in the glass with Ca₃Ga₂Ge₃O₁₂ composition were analysed and compared with corresponding Nd³⁺ parameters in their crystalline analogue with garnet structure. Experimental lifetimes are compared with those calculated, and quantum efficiency of Nd³⁺ centres from ⁴F_3/2 emitting level in the glass with Ca₃Ga₂Ge₃O₁₂ composition is estimated. Incorporation peculiarities and local structure of Nd³⁺ luminescence centres in the glass with Ca₃Ga₂Ge₃O₁₂ composition and corresponding Ca₃Ga₂Ge₃O₁₂:Nd³⁺ garnet laser crystals are considered. On the basis of extended X-ray absorption fine structure (EXAFS) spectra (L₃-edge) of rare-earth elements analysis it has been shown that Nd³⁺ luminescence centres in the CaO–Ga₂O₃–GeO₂ glass network occupy structural sites with the coordination number to oxygen N = 6.