EPR AND MAGNETIC SUSCEPTIBILITY STUDIES OF V4+ IONS IN 2B2O3·SrO GLASS MATRIX

Electron paramagnetic resonance (EPR) and magnetic susceptibility studies on xV2O5 ·(100 - x)[2B2O3 · SrO] glasses with 0≤ x ≤ 30 mol% were performed. The covalence degree of vanadium bonds was estimated according to the LCAO-MO model. The EPR data show the presence of V4+ ions in a square-pyramidal coordination (C4v). The experimental EPR spectra are simulated assuming a superposition of two signals, one with hyperfine structure (HFS) typical for isolated ions and the other one consists of a broad line without HFS characteristic for clustered ions. These results are consistent with the magnetic data which indicate that for x ≥ 5 mol% V2O5 the temperature dependence of the reciprocal magnetic susceptibility is described by a Curie–Weiss type law with negative paramagnetic Curie temperature. The magnetic data also allow the estimation of NV4+ / Ntotal ratio.

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