Non-standard measurement and evaluation of hysteresis loop of ferroelectrics

Abstract

A digital apparatus for automated hysteresis loop measurement controllled by a PC was designed, realized and verified. The only analogous instrument is a high voltage amplifier. Digital approach has many advantages, especially full automation, high flexibility due to the computer control, reduction of noise and line interference, exact data processing, data saving etc. The only disadvantage is a little reduction of real time processing. The resulting hysteresis loop can be presented by three different means: in time, frequency and field domain. The frequency spectrum, as a result of the discrete Fourier transform, is used for filtering, elimination of DC component, effective loop approximation etc. In the field domain the spectrum components can be displayed as Lissajouse figures and the dissipation power of individual harmonics can be found. Complete data processing gives a lot of information for the explanation of physical processes, design of ferroelectrics devices, etc.