Olivier Guillon

True Young modulus of Pb(Zr,Ti)O3 films measured by nanoindentation

In order to assess transverse elastic modulus of lead zirconate titanate (PZT) thin films, we used a nanoindenter with constant monitoring of the force. It is shown that the true elastic modulus, i.e., the low pressure elastic modulus, can be measured by this method. This permitted a determination that sputter deposited PZT (54∕46) films display a Young modulus close to a ferroelectric hard type PZT bulk ceramic. Moreover, this low pressure modulus is independent of grain size and thickness of the film, but this is no more true for high pressure modulus. This provides a step toward a better understanding of the properties of these PZT films and the possibility to better use them in microsystems.

Tensile fracture of soft and hard PZT

Power applications generate high stresses which can damage piezoceramic components. In this study tensile fracture of several types of PZT (hard/soft) is investigated. After validation of the specimen geometry by means of numerical simulation, samples are led to failure using a specific device. Weibull law parameters enable the characterisation of the tensile strength distribution and highlight clear differences between soft and hard ceramics. A fractographic approach emphasises the specificities of the fracture mode and the fracture origin for each type of samples.

Determination by Indentation Method of Sputtered PZT Films Mechanical Parameters for Si-MEMs Applications

ABSTRACT This paper presents our investigation in characterization of mechanical parameters of PZT thin films. In the present study, we aim at measuring the transverse biaxial elastic modulus and the hardness of these piezoelectric ceramic films using nanoindentation technique. First were these measurements necessary for checking the mechanical quality of our films. But we could demonstrate the possibility of this technique to measure the true biaxial elastic modulus. This was shown to be close to hard bulk PZT ceramics for the case of our sputtered films. Moreover, this comparatively simple technique gives insight in the mechanical properties of ferroelectric films having various grain size.

Uniaxial Electromechanical Behavior of a Soft PZT: Experiments and Modeling

The aim of this work is to collect a database from uniaxial experiments and model the material behavior. A soft PZT is tested in compression; the influence of stress rate seems to be negligible and the material accommodates to cyclic mechanical loadings. These responses are simulated by means of a phenomenological model taking into account the coupling between remnant strain and polarization thanks to a mechanically induced depolarization function.