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 E(c), 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 degrees switching in this tetragonal material. This is further corroborated by the effects of the film orientation and of electrical and stress poling.