One of the key points in the physics of the relaxors is their response to the applied DC field.Many studies of this topic were made,in particular on the influence of the field on the dielectric properties.However,prac...One of the key points in the physics of the relaxors is their response to the applied DC field.Many studies of this topic were made,in particular on the influence of the field on the dielectric properties.However,practically,in all the cases,the measurements were performed at a fixed frequency and usually with the change in the temperature at the fixed field strength.In this paper,we report the evolution of the dielectric spectra at low frequencies(0.1 Hz<ω<1 kHz)at fixed temperature 246 K on changing the DC electric field applied in(111)from 1 kV to 7 kV.Cole-Cole function was used to describe the spectra and the field dependences of the mean relaxation timeτ,the oscillation strengthΔεand the width parameterαwere determined.The obtainedτ(E)andΔε(E)provide evidence of the field-induced transition from the nonpolar glass-like phase to the nonpolar paraelectric phase at around 1.5 kV/cm.In the paraelectric phase,very fast hardening of the spectra was observed withτchanging from 10 s to about 10−4 s.The performed analysis demonstrated that the earlier reported positive C-V effect is completely determined by the spectra hardening,whileΔεdoes not show any change in the glass-like phase and monotonously decreases with a field increase in the paraelectric state.For complete understanding of the microscopic origin of the observed phenomena,a detailed study on the short-and long-range structures at the same condition is necessary.展开更多
基金The study was supported by Russian Science Foundation grant no.22-12-00328,https://rscf.ru/en/project/22-12-00328/.
文摘One of the key points in the physics of the relaxors is their response to the applied DC field.Many studies of this topic were made,in particular on the influence of the field on the dielectric properties.However,practically,in all the cases,the measurements were performed at a fixed frequency and usually with the change in the temperature at the fixed field strength.In this paper,we report the evolution of the dielectric spectra at low frequencies(0.1 Hz<ω<1 kHz)at fixed temperature 246 K on changing the DC electric field applied in(111)from 1 kV to 7 kV.Cole-Cole function was used to describe the spectra and the field dependences of the mean relaxation timeτ,the oscillation strengthΔεand the width parameterαwere determined.The obtainedτ(E)andΔε(E)provide evidence of the field-induced transition from the nonpolar glass-like phase to the nonpolar paraelectric phase at around 1.5 kV/cm.In the paraelectric phase,very fast hardening of the spectra was observed withτchanging from 10 s to about 10−4 s.The performed analysis demonstrated that the earlier reported positive C-V effect is completely determined by the spectra hardening,whileΔεdoes not show any change in the glass-like phase and monotonously decreases with a field increase in the paraelectric state.For complete understanding of the microscopic origin of the observed phenomena,a detailed study on the short-and long-range structures at the same condition is necessary.
