Thermal and crystallization behavior of aluminum-doped bismuth borate glasses

New glass samples with composition (56 − x)Bi₂O₃–(44 − y)B₂O₃–(x + y)Al₂O₃, where x and y ranges from 0 to 10 mol%, were prepared using the conventional melt-quenching-annealing technique. The amorphous nature of the samples was confirmed by X-ray Diffraction Analysis. The structural changes due to the introduction of Al₂O₃ were studied by Fourier-transform infrared spectroscopy. The thermal properties of these glasses were assessed using Differential Thermal Analysis and Dilatometry. It was observed that substitution of Bi₂O₃ and B₂O₃ by Al₂O₃ resulted in lower melting temperatures and thermal expansion coefficients, but higher glass transition, softening, and crystallization temperatures. The thermal stability of the glasses was also assessed using various thermal parameters. Crystalline phases in selected samples, heat treated at peak crystallization temperatures, were identified through X-ray Diffraction and Scanning Electron Microscopy micrographs. The density and molar volume of these samples were also precisely measured and calculated.