The converse piezoelectric response of a thin film constrained by a substrate is analyzed in different geometries under various boundary conditions. We considerthe effects of elastic deformation of the substrate on the total displacement of thefilm surface induced by the electric field. The change of film thickness and the bending curvature of a film/substrate couple are calculated. For a thin film island clamped on a large thick substrate, the theoretical estimation of the piezoresponse, including a local bending in the vicinity of the island/substrate interface, is in agreement with the finite element calculation.

In this paper we present a new method of the rapid construction of magnetic phase diagrams in a temperature-composition space, using magneto-optic imaging with an indicator film technique (MOIF). The method is applied for mapping the diagram for the La1–xCaxMnO3 colossal magneto-resistive oxide, using the spread films deposited on a SrTiO3 substrate. The constructed magnetic diagram is in a good agreement with data on uniform films and bulk crystals of this system. The MOIF study of transitions under cooling and heating has revealed the formation of a non-magnetic phase in the area of temperatures from 5 K to 57 K and compositions from x = 0 to x = 0.5.

The domain structure of the 400 nm thick PbZr0.2Ti0.8O3 (PZT) films with different electrode layer configurations was investigated by x-ray diffraction and transmission electron microscopy. The c-domain fractions of the PZT films with no electrode layer, with a 50 nm electrode layer between the film and the substrate, and with 50 nm electrode layers on top and bottom of the PZT film were found to be equal. This means that depolarizing fields do not affect the polydomain structure of the film. Calculations of the in-plane strains based on the lattice parameters of the La0.5Sr0.5CoO3 (LSCO) layer in the above configurations led to the conclusion that the bottom electrode layer is coherently strained to match the substrate.

The thermodynamic theory of the deformation of heterophase solids containing polydomain phases is presented. The polydomain phases consisting of twins are considered. Elastic interaction between twins leads to the formation of an equilibrium polydomain structure. Its basic element is a polytwin: a plane-parallel plate consisting of alternating plane-parallel twins. In a uniform single crystal the polytwin structure is unstable and should disappear at any uniform external stress. But it can be stable in a heterophase system. The evolution of the equilibrium structure with the variation of the external stress exhibits reversible superplasticity and pseudoelasticity. Two contributions into total strain are considered: due to displacements of twin boundaries inside a polydomain (polytwin) phase and due to movement of interfaces between polydomain and matrix phases.