#$%^&*AU2019100447A420190606.pdf#####Abstract Ceramic-based dielectrics are considered as the best candidates for high temperature capacitors because of their outstanding mechanical and electrical properties. Nevertheless, conventional barium titanate-based capacitors show narrow operating temperature ranges owing to the lower tetragonal-cubic phase transition temperature. In order to significantly increase the working temperature and relative permittivity, a novel (1-x)Nao.5Ko.5NbO3-xLa(Zno.Tio.5)3 (NKN-xLZT) ceramics were chosen to meet the targets in this work. The NKN-xLZT ceramics with sub-micrometer grains (0.2-0.4 pm) were synthesized via a conventional solid-state sintering route. A relative permittivity (e'= 1560 15%) with low loss tangent over wide temperature range from 96 °C to 350 °C was obtained in the x = 0.02 ceramics. Additionally, the crystal structure distortion and conduction behaviors of the NKN-xLZT ceramics were systematically studied. The decrease of oxygen octahedron distortion induced a weak electric dipole moment, and the high resistance (9x106 Qcm at 400 °C) greatly suppressed the long-term migration of defective ions in the ceramics. Therefore, the lower loss tangent and high dielectric permittivity still maintained at the high temperature. It believes that the NKN-xLZT ceramic system in this work will become one of the most promising candidates for high-temperature capacitor devices. 1
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