A novel Na0.5K0.5NbO3-La(Zn0.5Ti0.5)O-3 ceramics with excellent dielectric properties at wide temperature range
A novel Na0.5K0.5NbO3-La(Zn0.5Ti0.5)O-3 ceramics with excellent dielectric properties at wide temperature range
复制标题
一种在宽温度范围内具有优异介电性能的新型Na0.5K0.5NbO3-La(Zn0.5Ti0.5)O-3陶瓷
DOI：
10.1016/j.ceramint.2019.05.226
复制
发表时间：
2019
影响因子：
5.2
通讯作者：
Ouyang Shen
中科院分区：
文献类型：
--
作者：
Liu Zhiyong;Zhang An;Geng Xinhui;Lu Jinshan;Mao Yuqing;Ouyang Shen
陶瓷基电容器因其优异的机械和电气性能而被认为是高温电容器的最佳候选材料。然而，常规的钛酸钡基电容器由于低的四方-立方相转变温度而显示出窄的工作温度范围。为了提高陶瓷的工作温度和相对介电常数，本文选用了一种新型的（1-x）Na_（0.5）K_（0.5）NbO_（3-x）La（Zn_（0.5）Ti_（0.5））O_3（NKN-xLZT）陶瓷材料。采用固相烧结法制备了亚微米晶粒（0.2-0.4 μm）的NKN-xLZT陶瓷。x = 0.02的陶瓷在96 °C ~ 350 °C的较宽温度范围内具有较低的相对介电常数（ε' = 1560 ± 15%）。此外，还系统地研究了NKN-xLZT陶瓷的晶体结构畸变和导电行为。氧八面体畸变的减少导致了弱极化，高电阻（400 °C时为9 × 106Ωcm）极大地抑制了缺陷离子在陶瓷中的长期迁移。因此，低损耗角正切和高介电常数在高温下仍然稳定。相信本工作中的NKN-xLZT陶瓷系统将成为高温电容器器件最有前途的候选者之一。
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 low tetragonal-cubic phase transition temperature. In order to increase the working temperature and relative permittivity, a novel (1-x)Na0.5K0.5NbO3-xLa(Zn0.5Ti0.5)O3(NKN-xLZT) ceramics were chosen to meet the targets in this work. The NKN-xLZT ceramics with sub-micrometer grains (0.2–0.4 μm) were synthesized via a conventional solid-state sintering route. A relative permittivity (ε’ = 1560 ± 15%) with low loss tangent over wide temperature range from 96 °C to 350 °C was obtained in thex= 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 polarization, and the high resistance (9 × 106Ωcm at 400 °C) greatly suppressed the long-term migration of defective ions in the ceramics. Therefore, the low loss tangent and high permittivity were still stabilized 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.