Crystallization Kinetics and Structure Refinement of CaTiO3 Glass-Ceramics Produced by Melt-Quenching Technique

Abstract

Glass-ceramic materials were obtained by heat treatment (960 ºC for 2, 4, and 6 hs) of glasses with CaCO 3 47.50 wt%-TiO 2 23.75 wt%-SiO 2 23.75-Al 2 O 3 5.00 wt% formulation produced by the melt-quenching technique (melting at 1650 ºC and subsequent annealing at 650 ºC). The materials' structural characterization and crystallization kinetics (Kissinger method) indicate the presence of CaTiO 3 , CaSiO 3, and CaTiSiO 5 crystalline phases with activation energies 217, 281, and 446 kJ/mol, respectively. The structure refinement (Rietveld method) suggests metastability for the CaSiO 3 and CaTiSiO 5 phases as a function of the heat treatment time. The increase in time favors CaTiO 3 crystallization, from 62.97 wt%, in the 2 hs treated sample, to 79.21 wt%, in the 6 hs treated sample. EDS and microstructure analyses confirm the glass-ceramic production and indicate segregation of the CaTiO 3 phase for longer heat treatment times.