Effect of La2O3 concentration on structural, optical and cytotoxicity behaviours of strontium titanate borosilicate glasses

Lanthanum oxide-strontium titanate-borosilicate glasses with increasing content of La2O3 were prepared by the melt quench technique. X-ray diffraction results revealed the amorphous nature of the prepared samples which indicated the formation of glass. In order to study the structure of various glass samples, density and molar volume were calculated at room temperature by using Archimedes principle. Structural and optical properties were studied by employing infrared spectroscopy, Raman spectroscopy and UV-vis spectroscopy techniques. Direct and indirect optical band gap values were evaluated from Davis and Motts plots. The maximum and minimum optical band gap was found to be 3.54 and 3.46 eV. Urbach energy (EU), steepness parameter (σ), skin depth (δ) and electron phonon interaction (Ee-p) were also studied. The calculated values of EU were found to be increased from 0.30 to 0.33 eV with increasing the concentration of La2O3. Cytotoxicity of the synthesized glass samples was also performed. MTT assay was also performed to check the cell viability of the synthesized glass samples. These results revealed that the lower concentrations 1 μg/ml and 5 μg/ml of the glass sample STB9L are found to be safe for biological applications.