Abstract

Ferroelectric ceramic Li_xNa_{1 –x}Ta_yNb_{1 –y}O₃ (x = 0.17, y = 0–0.5) solid solutions with perovskite structure are synthesized for the first time by the thermobaric synthesis method (6 GPa, 1400–1800 K). The features of their structure and elastic properties are studied. It is shown that ceramic samples consist of grains of isomorphic shape and that faceting is inherent in the perovskite structure, allowing the coexistence of the rhombic phase of different symmetries of the P21ma and Pbcm unit cell. An increase in the synthesis temperature leads to a decrease in the Young’s modulus. The dispersion of the permittivity and its temperature dependence are studied. Specific static values of electrical conductivity and their temperature dependence, as well as the most probable relaxation time, are determined. Carrier activation enthalpies H_a and transport enthalpy H_m are calculated. It is established that the studied ceramic samples undergo a ferroelectric phase transition, while an increase in tantalum concentration lowers the Curie temperature. Li_0.17Na_0.83Та_0.1Nb_0.9O₃ in the paraelectric phase is found to be a superionic conductor.

中文翻译：

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Li 0.17 Na 0.83 Ta y Nb 1 – y O 3的陶瓷固溶体：热压合成，显微组织和性能

摘要

铁电陶瓷李_X娜_{1 - X}钽_ý铌_{1 - Ý} Ö ₃（X = 0 。 17，ÿ = 0 - 0 。 5）的钙钛矿结构的固溶体通过温压合成方法首次合成（6 GPA ，1400–1800 K）。研究了它们的结构和弹性特性。结果表明，陶瓷样品由同构形状的晶粒组成，并且钙钛矿结构中固有存在刻面，从而允许P 21 ma和Pbcm不同对称性的菱形相共存。晶胞。合成温度的升高导致杨氏模量的降低。研究了介电常数的分散性及其温度依赖性。确定电导率的特定静态值及其温度依赖性以及最可能的弛豫时间。计算载体活化焓H _a和运输焓H _m。可以确定的是，所研究的陶瓷样品经历了铁电相变，而钽浓度的增加则降低了居里温度。李_{0 。17} Na _{0 。83} Та _{0 。1} Nb _{0 。}发现顺电相中的₉ O ₃是超离子导体。