Optical and spectroscopic properties of neodymium doped cadmium-sodium borate glasses

Neodymium doped cadmium sodium borate glasses having composition xCdO-(40-x) Na2CO3-59.5H(3)BO(3)-0.5Nd(2)O(3); x = 10, 20 and 30 mol% were prepared by conventional melt-quenching technique. X-ray diffraction studies confirmed the amorphous nature of the prepared glasses. Conventional methods were used to determine the physical properties such as density, molar volume, refractive index, and rare earth ion concentration. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Omega(2), Omega(4) and Omega(6). The calculated intensity parameters were further used to predict the radiative transition probability (A), radiative lifetime (tau(R)) and branching ratio (beta(R)) for the various fluorescent levels of Nd3+ ion in the prepared glass series. The effect of the compositional changes on the spectroscopic characteristics of Nd3+ ions have been studied and reported. The value of Omega(2) is found to decrease with the decrease in the sodium content and the corresponding increase in the cadmium content. This can be ascribed to the changes in the asymmetry of the ligand field at the rare earth ion site and the change in rare earth oxygen (RE-O) covalency. Florescence spectra has been used to determine the peak wavelength (lambda(P))), effective line widths (Delta lambda(eff)) and stimulated emission cross-section (sigma(P)) for the F-4(3/2) -> I-4(9/2), I-4(11/2,) I-4(13/2) transitions of the Nd3+ ion. The reasonably higher values of branching ratios and stimulated emission cross-section for the prepared glasses points towards the efficacy of these glasses as laser host materials. However, the glass with more sodium content is found to show better lasing properties. (C) 2017 Elsevier Ltd. All rights reserved.