Different Sintering Method On Hydrothermal Synthesis Of Barium Titanate Ceramics Electrical Performance

BaTiO3is a typical perovskite ferroelectrics. The study of BaTiO3not only has certain representativeness, but also can be derived to other perovskite ferroelectrics. In this dissertation, nanocrystalline BaTiO3was hydrothermally synthesized at different reacting temperature. Then the BaTiO3nanopowders were sintered by conventional Single-Step Sintering (SSS) and Two-Step Sintering (TSS) process. Finally, their properties of phase structures, microstructures, sintering behavior, dielectric and ferroelectric was investigated, the main conclusions are as follows:(1) Nanocrystalline BaTiO3were hydrothermally synthesized at different reacting temperature and sintered at various temperatures to obtain BaTiO3ceramics with different grain sizes. By studying their properties of phase structures, microstructures, dielectric and ferroelectric, we get the following conclusions:XRD indicates that pure BaTiO3powders were synthesized in different reaction temperature, and BaTiO3ceramics are mainly composed of tetragonal. From SEM can be seen that grain size of the ceramic is increased with the increase of the sintering, and240℃and270℃preparation of BaTiO3ceramic samples had larger crystal size. Ceramic internal pore may influence stability of dielectric constant with frequency. Small grain size of BaTiO3ceramic reduce the Curie temperature. The dielectric loss peak was observed in the sample reacted at240℃and270℃. This is mainly due to the oxygen vacancies in BaTiO3sintered in a high temperature. Dielectric constant, dielectric loss and Curie temperature increase first and then decrease with the increase of sintering temperature. Because of BaTiO3powders have the difference of the granularity, granularity distribution, phase composition and morphology by hydrothermal method under the different reaction temperature, which can influence electrical properties of BaTiO3ceramics. And point defect also affects ferroelectric characteristics of the samples and lead double hysteresis loop.(2) BaTiO3ceramic was sintered by conventional SSS and TSS process, we get the following conclusion:SEM shows conventional Single-Step Sintering always accompanied rapidly grain growth in densification stage and the changes in the density values were not so obvious. Grain size of BaTiO3ceramic which was sintered by TSS process remain unchanged, and the density values was dependent on length of soaking time in T1and T2. Compared with conventional SSS, TSS process is easier to get grain homogeneous, and effectively reduce the internal porosity and cracks of the ceramics, the dielectric constant and remanent polarization were enhanced and not a significant change in Curie temperature. The dielectric constant and remanent polarization of BaTiO3ceramic depends on first-stage sintering and second-stage sintering of soaking time by two-step sintering preparation. But the dielectric loss values of the conventional SSS are less than TSS. We test the piezoelectric properties of the sample, which have a has a low dielectric loss values, namely TSS-2(T1=5min, T2=10h):d33=125pC/N.