Dielectric properties of (K0.5Na0.5)NbO3–(Bi0.5Li0.5)ZrO3 lead-free ceramics as high-temperature ceramic capacitors

• DOI: 10.1007/s00339-018-1757-4
• Publication Date: 2018-03-25T23:28:07Z
• Authors: Tianxiang Yan; Feifei Han; Shaokai Ren; Xing Ma; Liang Fang; Laijun Liu; Xiaojun Kuang; Brahim Elouadi
• Keywords: Tetragonal crystal system; Ceramic capacitor; Orthorhombic crystal system; Dielectric loss

(1 − x)K0.5Na0.5NbO3–x(Bi0.5Li0.5)ZrO3 (labeled as (1 − x)KNN–xBLZ) lead-free ceramics were fabricated by a solid-state reaction method. A research was conducted on the effects of BLZ content on structure, dielectric properties and relaxation behavior of KNN ceramics. By combining the X-ray diffraction patterns with the temperature dependence of dielectric properties, an orthorhombic–tetragonal phase coexistence was identified for x = 0.03, a tetragonal phase was determined for x = 0.05, and a single rhombohedral structure occurred at x = 0.08. The 0.92KNN–0.08BLZ ceramic exhibits a high and stable permittivity (~ 1317, ± 15% variation) from 55 to 445 °C and low dielectric loss (≤ 6%) from 120 to 400 °C, which is hugely attractive for high-temperature capacitors. Activation energies of both high-temperature dielectric relaxation and dc conductivity first increase and then decline with the increase of BLZ, which might be attributed to the lattice distortion and concentration of oxygen vacancies.