Thin Film Multilayers of Ferroelastic TiNi-Ferroelectric PZT: Fabrication and Characterization

Abstract

Heterostructure multilayers of ferroelastic TiNi coupled to thin film TiO₂ and ferroelectric lead zirconate titanate (PZT) produce a smart material capable of performing both sensing and actuating functions. An important issue is the ability to generate the appropriate crystalline phases of each of the materials and to minimize the chemical interactions from the surrounding material. TiO₂ and PZT thin films were deposited onto commercially available TiNi substrates by the sol-gel process. Minimum crystallization temperatures for the TiO₂ phases and PZT perovskite phases were determined and characterized by X-ray diffraction (XRD). For testing of the properties of these meso-scale structures to occur, the mechanical and electrical properties of the individual components need to be characterized. The mechanical properties of the PZT thin film were characterized by Scanning Electron Microscopy and optical microscopy. Cracking and defects in the PZT were observed for thick films; however thin PZT films of 1 micron or less showed better mechanical integrity. The ferroelectric properties of the PZT thin films were smaller than for bulk PZT; this was likely associated with leakage currents caused by the mechanical imperfections of the films.