Measurements of Dielectric Properties of Yttrium-Stabilized Zirconia Employing Spherical Dielectric Resonator Technique

Yttria-stabilized zirconia (YSZ) is a mechanically robust ceramic of interest for high-temperature microwave components and other applications requiring stable dielectric properties. However, reliable microwave permittivity data are difficult to establish due to strong dependence on composition, sample geometry, and the inherently limited sensitivity of broadband techniques for low-loss, high-permittivity dielectrics. This work presents the first application of the spherical dielectric resonator method, based on a recently formulated simplified electrodynamic model, to a non-magnetic dielectric material, extending the characterization across a broad temperature range. Spherical YSZ samples with 3.08 mol% Y₂O₃ content were characterized over the 5–17 GHz frequency range at room temperature and as a function of temperature from 20 °C to over 330 °C using dielectric resonator measurements in five different cylindrical cavities with a high electric energy filling factor in the sample ( $p_e\approx 0.96$ ). Complex permittivity was extracted with a simplified equivalent spherical-enclosure model and cross-checked for a representative case using a radial mode-matching approach. At room temperature, the extracted real part of permittivity was consistent across the investigated band, while the dielectric loss tangent was on the order of ${10}^{-3}$ and showed a slight increase with frequency. Temperature measurements indicated that both real part of permittivity and dielectric loss tangent increase monotonically with temperature. The obtained results provide a consistent microwave dataset for polycrystalline YSZ.