Good thermal stability and low dielectric loss of (K_0.47Na_0.47Li_0.06)NbO₃–(Bi_0.5Na_0.5)(Li_0.25Ta_0.75)O₃ ceramics in a wide temperature range

(K_0.47Na_0.47Li_0.06)NbO₃–(Bi_0.5Na_0.5)(Li_0.25Ta_0.75)O₃ [(1−x)KNLN–xBNLT, 0 ≤ x ≤ 0.02] ceramics were prepared via a traditional solid phase method. The phase structure of (1−x)KNLN–xBNLT ceramics was studied by X-ray diffraction and Raman spectroscopy. The relative permittivity of KNLN ceramics could be improved with adding BNLT. When x = 0.01, the ceramic exhibited large relative permittivity and good thermal stability from 70 to 375 °C (Δε/ε_70°C ≤ ± 12%), indicating that this material could be applied in capacitors with wider working-temperature range. As x = 0.005, the ceramics exhibited high piezoelectric constant of 180 pC N⁻¹ and good piezoelectric stability under 400 °C. The conductivity behavior of (1−x)KNLN–xBNLT ceramics at high temperature was also investigated, showing that the relaxation processes and mechanisms of conduction were thermal activation attributed by the double-ionized oxygen vacancy.