Microwave dielectric properties of potassium sodium niobate ceramics with different K/Na ratios

Potassium sodium niobate (K_xNa_1−xNbO₃) ceramics with different K/Na ratios were prepared by traditional solid reaction method and the complex permittivity at 8.2–12.4 GHz was measured in this study. Then the complex permittivity at GHz was compared with that at low frequency (KHz and MHz). And the influences of phase structure and microstructure on the dielectric properties were investigated. A lattice parameter discontinuity at x=0.5 was found and the ceramic with x=0.5 has well faceted and homogeneous grain size distribution compared with others. In addition, the reflection loss of the ceramics was calculated. All the ceramics possess better absorption property at the frequency around 11 GHz, while the effective absorption bandwidth is narrow. The ceramic with x=0 shows the best absorption property because of its relatively low dielectric permittivity.