Authors: M N Muralidharan C A Rasmitha R Ratheesh
Publish Date: 2008/08/14
Volume: 16, Issue: 6, Pages: 635-
Abstract
The luminescence properties of silica xerogels and aerogels have been studied using PL spectroscopy Both silica xerogels and aerogels exhibit photoluminescence in the visible region when excited with UV radiation The luminescence observed in xerogels and aerogels is attributed due to defect centers Silica aerogels exhibit better photoluminescence than xerogels due to the increase in defect sites The incorporation of rare earth ions La3+ Nd3+and Sm3+ enhanced the luminescence of both silica xerogels and aerogels La3+ shows least and Nd3+ shows maximum enhancement Increase in the concentration of Nd3+ resulted in an increase in the luminescence intensity The change in the environment of the defect centers due to the incorporation of rare earth ions and the superposition of 4ff transitions of rare earths are considered as the reasons for the luminescence enhancementThe authors are thankful to Dr KR Dayas Director CMET Thrissur for providing facilities to carry out this work We are also grateful to Dr KG Gopchandran for Luminescence measurements and Mr PA Abraham Mr Stanly Jacob and Mr C Rajesh for useful discussions
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