Investigation of the frequency dependence of the electrical conductivity in PZT piezoceramics

Abstract

Purpose. To investigate the frequency dependence of the electrical conductivity in piezoelectric ceramics based on solid solutions of lead-zirconate titanate oxides.Methodology. To obtain the frequency dependence of the electrical conductivity in piezoelectric ceramics based on solid solutions of lead-zirconate titanate oxides, we used a technique for measuring the resistance of a sample with electrodes deposited on its opposite faces. Using the obtained resistance value, the value of the electrical conductivity of the sample was calculated at various frequencies.Findings. The frequency dependence of the specific electrical conductivity in PZT-22 piezoceramics based on solid solutions of lead-zirconate titanate oxides in the frequency range of 0 < ν < 60 kHz has been obtained by the authors. The specific electrical conductivity in PZT-22 piezoceramics increased over the entire range of frequencies studied. A sharp increase in specific electrical conductivity was observed at frequencies up to 20 kHz. At frequencies of ν > 20 kHz the increase in specific electrical conductivity ceased and at frequencies of ν > 30 kHz its value reached saturation. The maximum value of specific electrical conductivity γ = 0.55 . 10-6 Ohm-1.m-1 was obtained at a frequency of 60 kHz. The frequency dependence of the specific electrical conductivity in PZT-22 piezoceramics in the frequency range of 0 < ν < 60 kHz is analyzed. It was found that the specific electrical conductivity in PZT-22 piezoceramics increases according to a power law in the frequency range of 0 < ν < 10 kHz. The mechanism of changing the electrical conductivity in PZT piezoceramics with increasing frequency of the electric field is discussed. A formula is obtained that satisfactorily describes the experimental dependence of the specific electrical conductivity in PZT-22 piezoceramics on the frequency of an alternating voltage in the frequency range of 0 < ν < 10 kHz and which corresponds to the power law of A. Ioncher. The specific electrical conductivity in the unpolarized PZT-19 piezoceramics increases in the frequency range of 0 < ν < 100 kHz. In the frequency range of 0 < ν < 20 kHz a power law dependence is observed and at frequencies of ν > 20 kHz a power law is violated and the specific electrical conductivity gradually increases without reaching saturation. Originality. The frequency dependence of the electrical conductivity in PZT-22 piezoceramics in the frequency range of 0 < ν < 60 kHz is studied. It is established that the specific electrical conductivity in PZT-22 piezoceramics increases with increasing frequency of the electric field and in the frequency range of 0 < ν < 10 kHz, the nature of its change corresponds to the power law of A. Ioncher. The mechanism of change in electrical conductivity is due to the hopping conductivity of ions and polarons in a dielectric and is explained by the delay of slow polarization mechanisms. The nature of the dependence of the specific electrical conductivity in PZT-19 piezoelectric ceramics is due to the fact that polarization processes do not make a noticeable contribution to the dispersion of the electrical conductivity of unpolarized piezoceramics and the delay of slow polarization mechanisms is not observed.Practical value. When using piezoceramics based on solid solutions of lead-zirconate titanate oxides, it is necessary to take into account the significant dependence of its electrical conductivity on the frequency of an alternating electric field. The research results can be used to study the mechanism of electrical conductivity of piezoceramic materials based on solid solutions of lead-zirconate titanate oxides, which are used in electrical and electronic products under the influence of alternating electric fields of various frequencies.