EPR studies of Cu2+ and V4+ ions in phosphate glasses |
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Authors: | O. Cozar I. Ardelean V. Simon L. David N. Vedean V. Mih |
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Affiliation: | (1) Faculty of Physics, Babes-Bolyai University, 400084 Cluj, Napoca, Romania;(2) Departament of Physics, North University, 430083 Baia Mare, Romania |
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Abstract: | Two lead-phosphate glass systems doped with both copper and vanadium ions in different ratios were studied by EPR (electron paramagnetic resonance) method. EPR spectra and parameters (g‖ = 2.44, g⊥ = 2.08 andA ‖ = 117.6 · 10−4 cm−1) obtained for x(CuO · V2O5)(l−x)[2P2O5 · PbO] glasses withx ≤ 10 mol% suggest a tetrahedral (Td) coordination of Cu2+ ions and not a tetragonally elongated octahedron as has been assumed in previous works. The ground state of the paramagnetic electron is thed xy copper orbital with a 4pz contribution of 6%. For 20 ≤x ≤ 40 mol% a broad line (ΔB = 307 G) characteristic for clustered ions appears atg = 2.18. The V4+ ions are evidenced only in the spectra of x(CuO · 2V2O5)(1 −x)[2P2O5 · PbO] glasses and the resonance parameters suggest a pentacoordinated C4v local symmetry for these ions. The hyperfine structures characteristic for Cu2+ and V4+ ions disappear for 10 ≤x ≤ 40 mol% due to the mixed exchange Cu2+−V4+ pair formation in these glasses. |
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