MAGNETIC AND OPTICAL-PROPERTIES OF BORATE GLASSES CONTAINING URANIUM IONS

Magnetic susceptibility and optical absorption measurements were perfo rmed on (1 - x)Na2B4O7 . xUO(2) and (1 - x)Na2B4O7 . xUO(3) samples wi th 0.05 less than or equal to x less than or equal to 0.30. The sample s were obtained by melting appropriate mixtures of Na2B4O7 and UO2 or UO3 at 1250 degrees C for 30 to 210 min. Optical spectra of these glas ses have absorption bands at 13 700, 15 600, 23 240 and 24 090 cm(-1), due to the different valence states of uranium ions. Our analysis sug gests the presence of uranium ions mainly as U6+ and, in small amounts , as U4+ and U5+. Magnetic susceptibility measurements were performed with a Faraday type balance in the 80 to 300 K temperature range. Samp les with x greater than or equal to 0.20 have paramagnetic behaviour ( temperature-independent for the equilibrated (1 - x)Na2B4O7 . xUO(3) a nd (1 - x)Na2B4O7 . xUO(2) samples, due to the U4+ ions, and temperatu re-dependent for the non-equilibrated (1 - x)Na2B4O7 . xUO(2) glasses, due to the U4+ and U5+ ions). The magnetic susceptibilities of the sa mples range from 0.3 X 10(-4) to 4 X 10(-4) emu/mol. The evolution of the redox process of uranium ions in the glass melts are followed by c hanges in the optical spectra and magnetic data with increasing meltin g time at 1250 degrees C.