Synthesis of Barium Titanate Compounds with Enhanced Dielectric Properties at Room Temperature
The addition of 22 mol% of different zirconia containing powders: cubic stabilized zirconia (8YSZ), tetragonal zirconia (TZ3Y), and pure zirconia to barium titanate (BaTiO3) was studied. X-ray diffraction analysis of the sintered compact made of these powder mixtures confirmed the presence of single phase peroviskate-like structure. The microstructure of the sintered samples showed different grain sizes, for different kinds of zirconia additives. The relative permittivity and the dielectric loss of the sintered pellets were measured at different temperatures and frequencies. The highest relative permittivity was obtained for samples having 22 mol% 8YSZ. The yttria addition to barium titanate zirconate had been discussed.
Microwave assisted synthesis of barium zirconium titanate nanopowders
The paper reports the synthesis, structural and high frequency dielectric properties of Ba(ZrxTi1−x)O3,BZT, nanopowders where x = 0, 0.1, 0.2, 0.3. These powders were synthesized using both microwave assisted and conventional heating, with the former requiring lower temperature and shorter times compared to the latter, viz., 700 °C for 30 min versus 900 °C for 5 h. The synthesized nanopowders were characterized using X-ray diffraction, micro-Raman spectroscopy, transmission electron microscopy, BET surface area analysis, differential scanning calorimetry and high frequency dielectric measurements. All the microwave synthesized BZT compositions were found to have well crystallized, finer nanoparticles with less agglomeration and higher dielectric permittivity compared to the conventionally prepared powders. The rapidity and less demanding processing conditions associated with the microwave assisted method augers well for the general applicability of the technique for the production of nanocrystalline powders.
Dielectric properties of modified PZT ceramics
The dependence of the dielectric constant on the electric field of PZT ceramics can be well explained by the mechanism of domain wall motion. The mobility of the domain wall is increased by the A-site vacancies, due to the reduction of local stress in the domains which undergo domain switching. But O-site vacancies and the grain boundary act as pinning points for domain walls, so the domain wall motion is reduced when O-site vacancies dominate and the grain size is small. As a result, the dielectric constant after poling was larger than that before poling and the coercive field were reduced by the addition of A-site vacancy produce. But the opposite results were obtained, when the O-site vacancy produce was added.