Nonlinear Dielectric Spectroscopy

In addition to linear dielectric spectroscopy in an extremely broad frequency range, a variety of field-dependent and pyroelectric measurements can be performed in our group. These methods can be used to investigate, e.g., P(E) hysteresis loops or spontaneous polarization in ferroelectrics or multiferroics. Also the non-linear properties of supercooled liquids are investigated, which helps understanding the dynamic processes at the glass transition.

Dielectric spectra can be collected applying maximum ac voltages of 4000 V (peak to peak) corresponding to electrical fields of up to several 100 kV/cm, depending on sample thickness and electric strength of the material. In this way, in addition to the conventional dielectric susceptibility at high fields, also its higher-harmonic components can be detected.

In addition, polarization vs. field hysteresis-curves can be measured, also allowing for a determination of the high-field dielectric permittivity, including its higher-harmonic components, at voltages up to 10 kV. The pyroelectric coefficient or the long-time relaxation of the remnant polarization can be determined as well as field-cooled/zero-field-cooled susceptibilities.

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