Experimental measurements of electro-mechanical constitutive behavior of four compositions of PZT

Four compositions of commercially available PZT are characterized under combined stress and electric field loading. The loading consists of a series of increasing compressive stress increments alternating with a series of bipolar electric field cycles. The softest composition has the lowest Young's modulus and shows hysteresis in the electric field cycle that increases as the compressive stress is increased. A distinct yield stress associated with the onset of deformation twinning (depolarization) is evident at around 25 Mpa. After loading to 180 Mpa and unloading, there is a large residual strain. The hardest composition has a higher Young's modulus, shows little or no hysteresis in the electric field cycle until the compressive stress has been applied, has a distinct yield point at around 75 Mpa associated with the onset of deformation twinning, and after loading to 180 Mpa and unloading the non-linear strain is recovered. There is no residual strain. The two compositions that lie between the extremes display intermediate behavior.