EPR and photopyroelectric investigations of Fe2O3-CaO-P2O5-SiO2 glass and glass-ceramic systems

Electron paramagnetic resonance (EPR) and standard photopyroelectric (PPE) measurements were carried out on 45(3.34CaO .P2O5)(55-x)SiO2. xFe(2)O(3) gl ass and glass-ceramic samples with 0 less than or equal to x less than or e qual to 30 mol % in order to obtain information on surrounding and magnetic interactions between iron ions introduced in CaO-P2O5-SiO2 matrice's and o n the thermal diffusivity, alpha, of the investigated samples, respectively . The Fe3+-EPR data indicate that the size of ferromagnetic particles incre ases after heat treatment and their surroundings become more ordinated due to the partial crystallisation of samples. The room temperature values of t he thermal diffusivity in the above-mentioned composition range are 0.41 x 10(-6) less than or equal to alpha less than or equal to 2.33 x 10(-6) m(2) /s. Vitroceramic samples obtained by heat treatment present a similar behav iour of the thermal diffusivity to that of the untreated samples. The tempe rature dependence alpha (T) in the range of interest (10-65 degreesC) indic ates a linear decrease of alpha with a slope of 10(-8) m(2)/s/degree.