ESR, IR and optical absorption studies of Cu²⁺ spin probe in <i style="">x</i>Na₂O-(50-<i style="">x</i>)ZnO-50B₂O₃ ternary glasses

Abstract

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ESR, IR and optical absorption studies on<b style=""> </b><i style="">x</i>Na₂O-(50-<i style="">x</i>)ZnO-50B₂O₃ ternary glasses containing Cu²⁺ spin probe have been carried out. The absence of band at 806 cm^-1 in the IR spectra indicates the absence of boroxol rings. Thus, the present glass system consists of borate triangles [BO₃] and borate tetrahedral [BO₄] structural units. It was also observed that structural changes are taking place with variation of Na₂O and ZnO contents. The hyperfine splittings in the parallel features of ESR spectra of Cu²⁺ are recorded for all compositions. ESR results show that the <b style="">g</b>_{|| >} <b style="">g</b>_{⊥<b style=""> </b>}indicating that the Cu²⁺ ion is in tetragonal distorted octahedral site and its ground state is <i style="">d</i>_x2_-y2. There is considerable variation in <b style="">g_||</b>and <b style="">A</b>_{||<b style=""> </b>}values with the increasing concentration of Na₂O, whereas no perceptible changes have been observed in <b style="">g</b>_⊥and <b style="">A</b>_⊥values. The observed optical absorption peak of Cu²⁺ has been found to be at 800 nm for <i style="">x</i>=25 mol% of Na₂O content. Bonding parameters are calculated from both optical and ESR data. All these variations clearly indicate the structural changes in the present glass system with varying Na₂O content.<b style=""></b>

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