The effect of rare-earth oxides on the crystallization of CaO–Al2O3–SiO2 glasses
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CaO–Al2O3–SiO2 –La2O3–Nd2O3 glass was prepared and their physical properties, such as density, glass transition temperature and crystallization temperature, were measured. The heat treatment of these glasses precipitated Ca2La8(SiO4)6O2 oxyapatite (CLS) crystal for 20CaO–10Al2O3–60SiO2–10La2O3 (mol%) glass and Ca2Nd8(SiO4)6O2 oxyapatite (CNS) crystal was precipitated with Nd2O3 substitution. Crystallization of these glasses was observed at the surface and internally within the samples. The spherical and stick-like crystals were observed throughout the bulk of the glasses and the surface crystal layer of oxyapatite crystals were strongly oriented along the c-axis. The apparent activation energies of crystal growth were estimated as 360 kJ mol−1.
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