Sintering of CaZrO3-based ceramic using mixed conventional and microwave heating

CaZrO3 exhibits attractive dielectric properties for applications as type I capacitors and mixed resonators. The relatively high permittivity combined with the low dielectric losses of this ceramic are convenient for processing such passive components. However, CaZrO3 is generally sintered at high temperature (about 1550 degreesC), which is detrimental from a technological point of view. Thus, the aim of this work is to investigate the possibility of processing CaZrO3 at lower temperature and a short processing time while maintaining a high density. To obtain this goal, microwave sintering has been developed in a single-mode microwave cavity. Microwave sintering of CaZrO3 was tested versus the resonance mode and by using various susceptors for combining microwave and conventional heating. Parallel to the process improvements, investigations of the effect of Zr non-stoichiometry and the addition of a sintering agent (lithium fluoride) were undertaken. By combining the optimized composition with the improved process, dense CaZrO3-based ceramics have been processed in a few minutes at relatively low temperature (lower than 1100 degreesC). Moreover, such samples exhibit satisfactory dielectric properties. (C) 2002 Kluwer Academic Publishers.