ELSEVIER October 1996 Materials Letters 28 (1996) 347-35 1 Photoluminescence study of Nd-doped sol-gel silica glasses J. Sahu, A. Biswas *, H.N. Acharya zyxwvutsrqponmlkjihgfedcbaZYXW Optical Fiber Unit, CRF, IIT Kharagpur, Kharagpur 721 302. India Received 5 March 1996; accepted 10 March 1996 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSR Abstract Photoluminescence spectra of the neodymium ion activated sol-gel silica glasses have been investigated as a function of heat treatment between room temperature and 1200°C. Gels under investigation were prepared by adding an appropriate amount of neodymium nitrate in different sols made from TEOS or fumed silica or a mixture of fumed silica and TEOS. The fluorescence peak wavelengths of neodymium ions in the silica matrix were very much dependent on the thermal history of gel samples and independent of sintering temperature. Keywords; Silica-neodymia gels glasses; Sol-gel; Photoluminescence; Heat treatments 1. Introduction Silica glass, for its excellent properties, is unique as a laser host material in that its physical properties can be varied by suitable choice of composition. In recent years, sol-gel processing offers a new ap- proach of producing SiO,--Nd,O, glasses [l-8] with homogeneously dispersed neodymia at concentra- tions higher than those in conventional techniques. Sol-gel processing is also attractive because glasses can be prepared more easily and at a lower tempera- ture than those required in traditional techniques. It is also believed that the potential for greater homo- geneity of rare-earth ions on a molecular scale re- duces concentration quenching and increases quan- tum efficiency. But the disadvantage of the process _ Corresponding author. is that the final product is very much dependent on the precursors, reaction conditions and subsequent heat treatment [4,9- 111. Several workers [ l-3,5,6,10,1 11 have studied flu- orescence spectra of Nd-doped sol-gel silica glasses. Pope and Mackenzie [ 1,2] have observed fluores- cence maxima around 1.08 pm for samples densified at 950 to 1100°C. However, Moreshead [3] observed the fluorescence maxima at 1.06 p.m. Berry and King [5] studied fluorescence spectra of Nd-doped gels with heat treatment. They have observed that the peak position shifted to the longer wavelength as firing temperature increased, reaching a maximum around 1.066 pm at 1125°C. A fluorescence maxi- mum at 1.088 pm has also been reported by the present authors [ 10,111. The present study is aimed at understanding the role of heat treatment on the fluo- rescence spectra of Nd-doped gels during gel-to-glass conversion. 00167-577X/96/$12.00 Copyright 0 1996 Elsevier Science B.V. All rights reserved. PII SO l67- 577X(96)00078- X