Phase structure, Raman spectroscopic, microstructure and dielectric properties of (K0.5Na0.5)NbO3–Bi(Li0.5Nb0.5)O3 lead-free ceramics

(1-x)(K0.5Na0.5)NbO3–xBi(Li0.5Nb0.5)O3 [(1-x)KNN–xBLN, 0 ≤ x ≤ 0.02] dielectric ceramics were synthesized by an ordinary sintering technique. The effects of Bi(Li0.5Nb0.5)O3 addition on the phase structure, microstructure and dielectric properties of KNN ceramics were studied. The phase structure of ceramics shifted from the orthorhombic to pseudo-cubic phase structure with increasing the content of Bi(Li0.5Nb0.5)O3. The addition of Bi(Li0.5Nb0.5)O3 depressed the transition temperature of the orthogonal and tetragonal phases, which is a benefit to the thermal stability of KNN ceramics. Especially, as x = 0.01, the ceramics have a high relative permittivity er (~ 1557), low dielectric loss tanδ (< 2.4%) and good thermal stability Δe/e150°C (≤ ± 10%) from 150 °C to 365 °C. Especially, when x = 0.005, the piezoelectric constant d33 was improved to 133 pC/N. Furthermore, the comprehensive properties of (1-x)KNN–xBLN (0 ≤ x ≤ 0.02) ceramics were enhanced significantly to those of pure KNN ceramics. These results indicate that these ceramics could be considered as the prominent promising candidates for high-temperature capacitor application.