The Effects of Bi2O3 on Optical, FTIR and Thermal Properties of SrO-B2O3 Glasses

Combined optical and FTIR were measured for binary bismuth borate glass together with samples containing 2.5 – 15 mol % Bi2O3 glasses to justify the role of bismuth (Bi3+) ions on the spectral properties. The density and molar volume values were calculated to obtain some insight on the compactness and structural arrangement in the network. DTA measurements were carried out to calculate the thermal transition parameters of the studied glasses and to justify their stability. Optical spectra reveal three strong UV-near visible absorption bands at 250, 275 and 310 nm due to collective absorption of trace iron (Fe3+) ions impurities together with absorption from Bi3+ ions at 360 nm. The absorption edges reveal an obvious increase with the Bi2O3 content. FTIR spectra reveal vibrational bands characteristic for triangular borate groups at 1200- 1600 cm−1, tetrahedral borate groups at 800 – 1200 cm−1 together with interference of Bi-O vibrations upon the introduction of Bi2O3. The observed bands at about 429, 465, and 595 cm−1 are related to BiO6 and the band at 879 cm−1 is related to BiO3 in the host sample 15 % Bi2O3. Thermal properties are found to depend on the Bi2O3 content depending on the specific role of the formed groups (BiO6, BO3) and their function as modifier or former together with the formation of nonbridging oxygens.