Phase transformation and anelastic behaviors of PMN-0.33PT single crystals via nanoindentation with different strain rates

Abstract

The Pb(Mg1/3Nb2/3)-PbTiO3 (PMN-PT) relaxor ferroelectric single crystals have been widely concerned because of their excellent dielectric and electromechanical coupling properties. The local mechanically induced phase transformation and the response to the anelasticity deformation of the [100]- and [110]-oriented poled PMN-0.33PT ferroelectric single crystals were investigated by nanoindentation technique. The continuous stiffness measurement method in the nanoindentation test system was used to measure the elastic modulus and hardness of the PMN-0.33PT single crystals with different crystallographic orientations under different strain rates. The results showed that elastic modulus (E) of the single crystals increase with the increase of strain rates. Changes in elastic modulus caused by the phase transformation. It was further confirmed from the pop-in point which was due to the phase transition under the different load rates in the loading part of load-displacement curves. There was a certain deformation relaxation (ha = hp-hne) defined as the difference between the residual depth (hp) and the elastic recovery depth (hne), which could be attributed to the phase transition. Furthermore, the variation of hardness with strain rates revealed the relationship between inelastic deformation and hardness.