Phase Structure, Microstructure and Dielectric Properties of (K0.5Na0.5)NbO3‐LaFeO3 High‐Temperature Dielectric Ceramics

The (1-x)(K0.5Na0.5)NbO3-xLaFeO3 (abbreviated as (1-x)KNN-xLF, x = 0–0.03) ceramics were synthesized by the conventional solid-state sintering method. X-ray diffraction analysis shows that the phase structure of the (1-x)KNN-xLF ceramics transfers from orthorhombic to pseudocubic with increasing the LF content. The SEM studies reveal that a small amount of LF, as a grain growth inhibitor, has an evident effect on grain size reduction. The (1-x)KNN-xLF (x = 0.02) ceramics show high permittivity maximum (near 2000) and low dielectric loss (<5%) in the temperature range of 100–400°C, and the capacitance variation (ΔC/C150°C) is keeping within ±15%, indicating the potential application for the high-temperature capacitors.