Elucidation of the switching processes in tetragonal pzt by hysteresis loop and impedance analysis

The switching process in tetragonal PZT films is studied. The ferroelectric capacitors show rectangular P-E hystersis loops with very abrupt switching characteristics. Small signal impedance measurements as function of DC bias voltage reveal an abrupt drop of the parallel capacitance C near the switching field EC, coinciding with a sharp peak of the equivalent parallel conductance G, different from the more gradual variation of C and G with broad peaks near EC as typically observed in materials with MPB composition. This behavior is correlated to strong 180° switching in this tetragonal material. This is further corroborated by the effects of the film orientation and of electrical and stress poling.