Influence of the Structure on Magnetic Properties of Calcium-Phosphate Systems Doped with Iron and Vanadium Ions

The aim of this study was to prepare and characterize the glasses made of x(Fe$_{2}$O$_{3}$∙V$_{2}$O$_{5}$)∙(100 − x)[P$_{2}$O$_{5}$∙CaO] with x ranging of 0–50%. The contribution of Fe$_{2}$O$_{3}$ and V$_{2}$O$_{5}$ amount on the structure of P$_{2}$O$_{5}$·CaO matrix was investigated. The vitreous materials were characterized by XRD (X-ray diffraction analysis), EPR (Electron Paramagnetic Resonance) spectroscopy, and magnetic susceptibility measurements. A hyperfine structure typical for isolated V4+ ions was noticed to all spectra containing low amount of V$_{2}$O$_{5}$. The XRD spectra show the amorphous nature of samples, apart x = 50%. An overlap of the EPR spectrum of a broad line without the hyperfine structure characteristic of clustered ions was observed with increasing V2O5 content. The results of magnetic susceptibility measurements explain the antiferromagnetic or ferromagnetic interactions expressed between the iron and vanadium ions in the investigated glass.