Anomalous electron channeling in PZT thin films

Abstract

The study of the surface of lead zirconate-titanate (PZT) thin films using a scanning electron microscope (SEM) identified the patterns of electron channeling on the surface of the perovskite phase crystals. However, the observation conditions were completely uncommon and contradicted model representations. Thus, there was enough evidence to believe that the observed patterns of electron channeling were an anomaly. It was necessary to conduct an additional detailed study of the perovskite crystal in a PZT thin film in order to clarify which conditions could cause this anomaly. In particular, the method of electron backscatter diffraction (EBSD) in SEM was used to study the crystallographic specific features of the crystal. The method is based on the collection and automatic processing of electron diffraction patterns which calculate a corresponding crystallographic orientation for each point on the scanned crystal surface. As a result, the study revealed the unusual features of the crystallographic structure of perovskite in a PZT thin film that provided an opportunity for the manifestation of anomalous electron channeling. The research showed that the crystal lattice of perovskite experienced an axially symmetric monotone bend, which determined the round shape of the crystal. The study demonstrated the possibility of producing ferroelectric crystals with a curved crystallographic surface. In order to describe the growth of round perovskite crystals from the amorphous phase in PZT thin films, the author provided a dislocation model where the continuous bending of the perovskite crystal lattice could be explained by the accommodationof mechanical stresses with a decrease in the phase volume of the film material. In addition, it was shown that the bands observed in the electron channeling patterns corresponded to crystallographic planes, while any distortions of the pattern indicated a local deformation of the lattice in a highly symmetrical uniformly curved perovskite crystal in a PZT thin film