Non-isothermal crystallization kinetics study on Holmium and Yttrium-doped aluminosilicate glass systems

Holmium-166 and Yttrium-90, with suitable beta energies and in the form of glass microsphere find potential application in Selective Internal Radiation Therapy (SIRT) for liver cancer treatment. Present study focuses on the synthesis and crystallization kinetics of Yttrium aluminosilicate (YAS) and Holmium aluminosilicate (HAS) glasses with compositions: YAS (mass%): 40Y2O3-20Al2O3-40SiO2 and HAS (mass%): 38Ho2O3-21Al2O3-41SiO2, optimized for liver cancer radiotherapy application. Glasses were prepared via melt-quench technique in the temperature range of 1600–1650 °C. X-ray diffractometer (XRD) confirmed amorphous nature of these glasses. Measured densities were, 3.45 g cm−3 and 3.78 g cm−3 for YAS and HAS glass, respectively. To have a better understanding on thermal and glass stability of these system, thermal and growth kinetic studied was carried out using DTA technique. Both model-free and model-fitting approaches were applied to evaluate and compare the kinetic parameters. Activation energy for crystallization (Ea) values calculated from model fitted kinetics are the range of 300-320 kJ mol−1 for HAS glass and in the range of 428 to 453 kJ mol−1 for YAS glass. Model free kinetic based on Iso-conversional analysis showed Ea value of 258 kJ mol−1 for HAS glass and 425 kJ mol−1 for YAS glass at 90% conversion, which are in close match with model fitted data. Avrami parameters (n) of values < 3, indicated bulk crystallization with two-dimensional growth. Temperature has marginal effect on Avrami parameter, showing a marginal increase with temperature for both the glasses. Isothermal data were simulated to understand long-term behavior at a temperature which is beyond experimental limitation and time-temperature-transformation (T-T-T) diagram was constructed to know the critical cooling rates and conversion details for each glass system. YAS glass demonstrated greater resistance to crystallization, making it more suitable for long-term applications in SIRT compared to HAS glass. Finding of present studies enhances understanding of YAS and HAS glasses for advanced medical therapies and explore the path for other potential applications.