Study on the structure of SiO2–B2O3 xerogels with Eu3+ and sulfosalicylic acid as a probe

Eu3+-doped and sulfosalicylic-acid (Sal)-doped SiO2–B2O3 xerogels were prepared separately using the sol–gel method. The structure of SiO2–B2O3 xerogels with different SiO2/B2O3 ratio was studied by infrared (IR) spectra and fluorescence spectra with Eu3+ and sulfosalicylic acid as a probe. Furthermore, the structural evolution in SiO2–B2O3 xerogels to glass conversion was also studied. The results showed that devitrification or crystallization did not take place in the experimental heat-treatment temperature range up to 800°C. At low temperature the B–O bonds were essentially non-bridge links, which at latter stages evolved towards terminal Si–O–B bonds. The three-dimensional Si–O–B network could be formed upon heating to 500°C.