Authors: R Stefan D Simedru A Popa I Ardelean
Publish Date: 2012/01/04
Volume: 47, Issue: 8, Pages: 3746-3751
Abstract
xV2O5·100 − x07P2O5·03CaO glass system was obtained for 0 ≤ x ≤ 35 mol V2O5 In order to obtain information regarding their structure several techniques such as XRay diffraction FTIR and EPR spectroscopies were used XRay diffraction patterns of investigated samples are characteristic of vitreous solids FTIR spectra of 07P2O5·03CaO glass matrix and its deconvolution show the presence in the glass structure of all structural units characteristic to P2O5 Their number are increasing for x ≤ 3 mol V2O5 then for higher content of vanadium ions the number of phosphate structural units are decreasing leading to a depolymerization of the structure The structural units characteristic to V2O5 were not evidenced but their contribution to the glass structure can be clearly observed EPR revealed a well resolved hyperfine structure hfs typical for vanadyl ions in a C4v symmetry for x ≤ 3 mol V2O5 For 5 x 20 mol V2O5 the spectra show a superposition of two EPR signals one due to a hfs structure and another consisting of a broad line typical for associated V4+–V4+ ions For x ≥ 20 mol V2O5 only the broad line can be observed The composition dependence of the linewidth suggests the presence of dipole–dipole interaction between vanadium ions up to x ≤ 5 mol V2O5 and superexchange interactions between vanadium ions for x 5 mol V2O5
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