Temperature-dependent dielectric behavior of A₆B₂O₁₇ (A = Zr, Hf; B = Nb, Ta) phases

We report on temperature-dependent dielectric behavior of disordered ternary A₆B₂O₁₇ (A = Zr, Hf; B = Nb, Ta)-form oxides in the GHz frequency range. The microwave dielectric properties including relative permittivity, dielectric loss, and temperature-dependent relative permittivity were characterized using cylindrical dielectric resonators using a resonant post measurement technique. Dielectric measurements through the resonant post method approach generally agree with dielectric measurements of A₆B₂O₁₇ bulk ceramics measured through standard resonant post techniques. Coefficients describing the temperature-dependent relative permittivity for ternary A₆B₂O₁₇ phases are strongly positive, suggesting contributions to polarizability arising from long-range mechanisms potentially associated with structural disorder. These observations support the working hypothesis that material functionality can be engineered by the chemical diversity and structural disorder possible in high configurational entropy A₆B₂O₁₇ phases.