Microstructures of Zirconium Titanate Powders and Ceramics Prepared by Solid-State Mixed Oxide Method
Zirconium titanate (ZrTiO4): ZT powders were prepared by solid-state mixed oxide method. The mixed powder was calcined at various temperatures for 3 h ranging from 1100 to 1400 oC with a heating rate of 5 oC/min. X-ray diffraction analysis of the powders was performed using a diffractometer with Cu Ka. Pyrochlore phase was observed for calcinations below 1300 oC. In general, the strongest reflections apparent in patterns could be matched with a JCPDS file number 74-1504. The optimum calcination temperature for the formation of ZrTiO4 phase was found to be about 1300 oC for 3 h with heating rate of 5 oC/min. The microstructures of calcined powders were examined using scanning electron microscope (SEM). The particle size of powder increased with increasing calcination temperature. The ZT ceramics sintered at 1450, 1500, 1550 and 1600 oC for 4 h with heating rate of 5 oC/min, were checked for phase formation by X-ray diffraction. The density of sintered samples was measured by Archimedes method. The microstructures of sintered samples were examined using scanning electron microscope (SEM). The average grain sizes were checked by linear interception method. It was found that, the samples sintered at 1450 and 1500 oC gave rise to high purity ZT ceramics and the peaks matched well with ZrTiO4 phase in a JCPDS file number 74-1504. Unknown phases were found in ZT ceramics sintered at 1550 and 1600 oC. The value of density was in the range of 4.32 - 4.92 g/cm3 or 84.26 - 96.12 % of the ZT theoretical density. The densification of ZT ceramics decreased with increasing sintering temperature. The ZT ceramics sintered at 1450 and 1500 oC showed the average grain size of 8.55 and 12.55 µm, respectively. At sintering temperature 1550 and 1600 oC, morphology of grains changed to plate like crystals of second phases.
C. Puchmark and P. Tipparak, "Microstructures of Zirconium Titanate Powders and Ceramics Prepared by Solid-State Mixed Oxide Method ", Advanced Materials Research, Vols. 55-57, pp. 145-148, 2008