Ultra Wide Range Dielectric Spectroscopy of Strontium Titanate-Strontium Zirconate Solid Solution

摘要

The dielectric properties vary significantly with the B-site cations in ABO_3 perovskite-type oxides. In this study, we tried to understand the difference in the dielectric properties between SrTiO_3 (STO, epsilon_r = 290, Qf=3000 GHz) and SrZrO_3 (SZO, epsilon_r = 30, Qf= 13700 GHz) by measuring the dielectric spectroscopy of their solid solutions in a wide frequency range. The dielectric permittivity and the loss tangent (tan delta) of SrZr_xTi_(1-x)O_3 (STZ, 0.0<=X<= 1.0) ceramics were evaluated up to a GHz region using the planer electrode method and ring resonator method. The four-parameter-semi-quantum (FPSQ) model was employed to analyze the Infrared-reflectivity (IR-reflectivity) data of the STZ ceramics. Both dielectric properties up to the GHz region and IR reflectivity in the THz region were incorporated in the analysis to accurately determine the optical phonon parameters. Ultra wide band dielectric spectra of the SZT ceramics and the STO single crystal were presented. The ionic polarization dominantly determined the dielectric permittivity of the SZT ceramics and the STO single crystal. High permittivity of STO was due to the Slater mode. The decrease of dielectric permittivity and the Q-factor (= 1/tan delta) with an increasing Zr content (x) in STZ ceramics was attributed to the depression of the Slater mode. The effect of the optical phonon parameters on the permittivity and tan delta in the microwave region was simulated to generalize the results obtained for the STZ ceramics.