Optical properties of ytterbium ion doped phosphate glass prepared by sol-gel method

Abstract

Series of P2O5-Al2O3-Na2O doped YbCl3 glasses have successfully been prepared by sol-gel method. The amorphous nature of glasses are characterized using X-ray Diffraction (XRD) technique while the actual glass composition is determined using the Energy Dispersive of X-ray Analysis (EDAX). Meanwhile, the optical energy gap (Eg), Urbach energy (∆E) and the refractive index of glass are studied usingUV-Visible Spectroscopy in the wavelength range of 200nm-800nm. The glass transmission characteristic has been investigated using Infrared (IR) and Raman Spectroscopy. It is found that all glasses are amorphous in nature with composition is largely dominated by the amount of P2O5. It is also found that the energy gap, Eg increases from 3.30eV to 3.50eV as the Yb3+ content is increased. On the other hand, the Urbach energy, ∆E lies in the range of 0.58eV to 0.21eV, decreasing with the increasing of Yb3+ content. Furthermore, the refractive index reduces from 1.43 to 1.41 by the addition of Yb3+ and almost constant as the amount of Yb3+ is about 1.7 mol % or more.The changes of Eg,∆E and refractive index with the increasing amount of Yb3+ dopant content can be understood in terms of the changes in glass network. The IR and Raman Spectroscopy studiesrevealed that the glass exhibits seven vibration modes which are due to P=O vibration, PO2 asymmetric stretching vibration, νas(PO2), PO2 symmetric stretching vibration, νs(PO2), the ν(PO) groups, the νas of POP groups, the νs of POP groups and the deformation mode groups of the AlO and NaO vibration. The IR and Raman spectra show no significant distortion of the phosphate groups with Yb3+ ions doping level.