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 V 4+ 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 V 2 O 5 content. The results of magnetic susceptibility measurements explain the antiferromagnetic or ferromagnetic interactions expressed between the iron and vanadium ions in the investigated glass.