Abstract
Combined optical and FTIR were measured for binary bismuth borate glass together with samples containing 2.5 – 15 mol % Bi
2
O
3
glasses to justify the role of bismuth (Bi
3+
) 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 (Fe
3+
) ions impurities together with absorption from Bi
3+
ions at 360 nm. The absorption edges reveal an obvious increase with the Bi
2
O
3
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 Bi
2
O
3
. The observed bands at about 429, 465, and 595 cm
−1
are related to BiO
6
and the band at 879 cm
−1
is related to BiO
3
in the host sample 15 % Bi
2
O
3
. Thermal properties are found to depend on the Bi
2
O
3
content depending on the specific role of the formed groups (BiO
6
, BO
3
) and their function as modifier or former together with the formation of nonbridging oxygens.