<span style="font-size:15.0pt;mso-bidi-font-size: 14.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:Mangal;mso-ansi-language:EN-GB;mso-fareast-language:EN-US; mso-bidi-language:HI;mso-bidi-font-weight:bold" lang="EN-GB">Spectroscopic studies of Cu²⁺ spin probe in sodium niobium based tellurite glasses</span>

Abstract

<span style="font-size:9.0pt;mso-bidi-font-size: 12.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">Differential scanning calorimetry (DSC), electron spin resonance (ESR), Raman, infrared (IR) and optical absorption studies on<b> </b>10Na₂O-xNb₂O₅-(89-x)TeO₂-1CuO glasses (where x =0, 5, 10, 15 and 20 mol%) containing Cu²⁺ spin probe have been carried out. Glass transition temperature (<i style="mso-bidi-font-style: normal">T_g</i>) and thermal stability of glass samples have been estimated from the DSC measurements and it has been found that both increase with increasing the Nb₂O₅<i style="mso-bidi-font-style: normal"> </i>content<i style="mso-bidi-font-style:normal">. </i>From Raman and IR spectra, it is clear that present glass system consists of structural units of TeO₃ (tp) and TeO₄(tbp) and NbO₆octahedra. Also, TeO₄ units convert into TeO₃ units with change in Nb₂O₅ content. The hyperfine splittings in the parallel features of ESR spectra of Cu²⁺ are recorded for all compositions. ESR results show that <span style="mso-bidi-font-weight:bold">g_{|| >} g<Sub><img src='http://www.niscair.res.in/jinfo/line.gif' border=0></sub> indicating that the <span style="font-size:9.0pt;mso-bidi-font-size:12.0pt;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";mso-bidi-font-family:mangal;="" mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:hi"="" lang="EN-GB">Cu²⁺ <span style="mso-bidi-font-weight:bold">ion is in tetragonal distorted octahedral site and its ground state is d_{x2- y2.} There is considerable variation in Hamiltonian parameters for the different compositions. The observed optical absorption peak of Cu²⁺ is found to be maximum at 780 nm for 10 mol% of Nb₂O₅ content.<span style="mso-bidi-font-weight:bold"> Bonding parameters and % bonding symmetry are calculated from both optical and ESR data changing with increasing Nb₂O₅ content. </span></span></span></span></span></span>