Báo cáo hóa học: " Crystal structure and electrical properties of bismuth sodium titanate zirconate ceramics"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Crystal structure and electrical properties of bismuth sodium titanate zirconate ceramics | Rachakom et al. Nanoscale Research Letters 2012 7 57 http content 7 1 57 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Crystal structure and electrical properties of bismuth sodium titanate zirconate ceramics Ampika Rachakom1 Panupong Jaiban1 Sukanda Jiansirisomboon1 2 and Anucha Watcharapasorn1 2 Abstract Lead-free bismuth sodium titanate zirconate where x and mole fraction BNTZ ceramics were successfully prepared using the conventional mixed-oxide method. The samples were sintered for 2 h at temperatures lower than 1 000 C. The density of the BNTZ samples was at least 95 of the theoretical values. The scanning electron microscopy micrographs showed that small grains were embedded between large grains causing a relatively wide grain size distribution. The density and grain size increased with increasing Zr concentration. A peak shift in X-ray diffraction patterns as well as the disappearance of several hkl reflections indicated some significant crystal-structure changes in these materials. Preliminary crystal-structure analysis indicated the existence of phase transition from a rhombohedral to an orthorhombic structure. The dielectric and ferroelectric properties were also found to correlate well with the observed phase transition. Keywords ceramics X-ray diffraction dielectric properties ferroelectricity Background Lead-based PbTiO3-PbZrO3 solid solutions have dominated the market of actuator and sensor materials due to their excellent ferroelectric and piezoelectric properties. In particular a compositional ratio of Zr Ti of around 52 48 showed the morphotropic phase boundary between a tetragonal and a rhombohedral phase where enhanced polarizability and optimum domain orientation were observed 1-6 . However PbO loss during high-temperature processes is considered to be environmental pollution with additional problems of recycling and waste disposal. .

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