Duplex structure in K0.5Na0.5NbO3-SrZrO3 ceramics with temperature-stable dielectric properties

Temperature-stable dielectric properties have been developed in the 0.86 K0.5Na0.5NbO3-0.14SrZrO3 solid solution system. High dielectric permittivity (ε′ = 2310) with low loss sustained in a broad temperature range (−55-201 °C), which was close to that of the commercial BaTiO3-based high-temperature capacitors. Transmission electron microscopy with energy dispersive X-ray analysis directly revealed that submicron grains exhibited duplex core-shell structure. The outer shell region was similar to the target composition, whilst a slightly poor content of Sr and Zr presented in the core region. Based on Lichtenecker's effective dielectric function analysis along with Lorentz fit of the temperature dependence of dielectric permittivity, a plausible mechanism explaining the temperature-stable dielectric response in present work was suggested. These results offer an opportunity to achieve the X8 R specification high-temperature capacitors in K0.5Na0.5NbO3 based materials.