New Na0.5Bi0.5TiO3–NaTaO3-Based Perovskite Ceramics
X-ray diffraction analyses and scanning electron microscopy revealed that Na0.5Bi0.5TiO3 (NBT) and NaTaO3 (NTa) form solid solutions across the whole concentration range. With increasing NTa content the symmetry of the solid solutions gradually changed from rhombohedral, on the NBT-rich side, to orthorhombic, on the NTa-rich side. No morphotropic phase boundary was found between these phases. With increasing NTa content, the perovskite lattice parameter (ap) and the sintering temperature increase, whereas the grain size decreases. In the case of pure NTa, ceramics with a secondary phase were obtained, identified as Na2Ta8O21, which was formed during the sintering process. A study of the dielectric properties showed that with an increasing concentration of NTa, there was a reduction and broadening of the permittivity maximum, a reduction of the temperatures of the dielectric anomalies, and a reduction of the dielectric losses.
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Document Type: Research Article
Affiliations: Advanced Materials Department, Jožef Stefan Institute, Ljubljana 1000, Slovenia
Publication date: 2007-11-01