Physical and optical properties of lithium potassium borate glass doped with neodymium

Abstract

A series of glass based on the composition of 20Li2CO3 : 10K2CO3 : (70-x)B2O3 : xNd2O3, where 0 = x = 1.3 mol % have been successfully prepared by conventional melt-quenching technique. The X-Ray Diffraction (XRD) spectra obtained confirmed the amorphous nature of the glass samples. The physical properties which includes density, ion concentrations, polaron radius and inter-nuclear distance have been determined. The glass transition temperature, crystallization temperature and melting temperature were determined by using Differential Thermal Analysis (DTA). The thermal stability of the glasses were increased with successive increase of Nd2O3 concentration. Infrared spectra were recorded at room temperature from 400 – 4000 cm-1. The bands arising from the vibrations of the borate network were observed in the range of 500 – 1600 cm-1. Since no peaks is observed at 806 cm-1, there are no boroxol ring involved and the glass network structure were expected to consists of randomly connected BO3 and BO4 units. The absorption spectra obtained from UV-Vis-NIR spectroscopy revealed eight absorption peaks, with the highest intensity at 581 nm. The increment of dopant concentrations had increased the absorption intensity of the glass samples. Based on the absorption measurements, the optical band gap energy and refractive index have been determined. Energy band gap show a maximum for 0.7 mol % and a minimum for 0.3 mol % of Nd2O3 concentrations. While refractive index shows an opposite trend with energy band gap. Photoluminescence spectra of doped glass samples exhibits three emissions in visible region under 310 nm excitation wavelength. It is observed that a violet, blue and green emission occurred at 420 nm, 484 nm and 538 nm due to 2P1/2 ? 4I9/2, 4G9/2 ? 4I9/2 and 4G7/2 ? 4I9/2 transitions of neodymium ions, respectively.