Abstract
In this work, stress-induced relaxation processes in sol-gel derived lead zirconate titanate (PZT) films with a Zr/Ti ratio of 30/70 were investigated by nanoindentation with a spherical tipped conductive indenter. The capacitance and electrical current transient flowing through the film under short-circuit conditions were measured as a function of constant nanoindentation force in the time domain. Measurements on piezoelectric films of different thickness indicated a significant mechanical clamping of the ferroelectric domains produced by the substrate. It is demonstrated that both the dielectric and electro-mechanical relaxation behavior are dependent on stress state in the film, which is affected during indentation. The relaxation of the electromechanical response is found to follow a stretched exponential function, the parameters of which are dependent on the indentation force and film thickness. On the other hand, the small signal capacitance measurement showed much slower relaxation characterized by a logarithm-time dependence. The differences observed in time response of dielectric and piezoelectric properties are related to different relaxation mechanisms and discussed in terms of stress-enhanced domain-wall movement. †On leave from the Institute of Materials Research, Slovak Academy of Sciences, Košice, Slovak Republic.
Published Version
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