Dielectric Spectra of BaTiO3-Based Materials Measured by Impedance Analyzers up to 1 GHz

Abstract

A new analysis procedure was proposed to determine the dielectric permittivity of materials with relatively high permittivity and high dielectric loss by a lumped impedance measurement using impedance analyzers. The samples used for the measurement were BaTiO3, (Ba0.6,Sr0.4)TiO3 and Ba(Zr0.25,Ti0.75)O3 ceramics. Resonance peaks were observed at hundreds MHz in the permittivity vs frequency curves calculated from raw impedance data, which was due to the self-inductance of the samples. The electric length corresponding to the self-inductance was determined from the curves of the reflection coefficient vs the calibration value of the electric length measured for a brass disc with the sample dimension. The capacitance of the samples was determined from the electric length corresponding to the capacitance in the measuring circuit. This electric length could be obtained from the electric length corresponding to the self-inductance and that at the quarter-wave resonance. The resonance peaks were successfully eliminated by the procedure proposed in this study. The permittivity vs frequency curve of Ba(Zr0.25,Ti0.75)O3 showed a broad dielectric relaxation above 100 MHz, while that of (Ba0.6,Sr0.4)TiO3 showed an almost flat dielectric relaxation up to 1 GHz.