FT-EPR SPECTROSCOPIC STUDY OF SILICOPHOSPHATE GLASSES DERIVED FROM GELS

(100 - x) mole% SiO2 - x mole% P2O5-glasses with x = 1-9 have been pre pared by the sol-gel process using tetraethylorthosilicate and triethy lphosphate as precursors. The gels were fired at various temperatures up to 950 degrees C and then exposed to gamma-ray irradiation to induc e paramagnetic centers. CW-EPR and FT-EPR Spectroscopies were employed at temperatures between 4 and 300 K in order to determine the resulti ng structures. The dried gels exhibited four types of O-2(-)-ions trap ped in pores of different sizes. The gels fired at T = 670 degrees C e xhibited the E(1)'-center and non-bridging oxygen as a results of the fracture of the Si-O-Si bonds. At higher temperatures, the spectra of the POHC, POHCb, E', and CH3--centers have been detected that are a fu nction of x and T.