Effect of electron channeling in the crystal lattice of radiant spherulites

Abstract

The paper presents the results of the microstructure study of spherulitic islands in thin films of lead zirconate titanate, characterized by either a non-uniform radial rotation of the crystal lattice (radiant microstructure) or a uniform rotation, which allows one to detect Kikuchi lines of electron channeling. Thin lead zirconate titanate films were obtained by a two-stage method of radio-frequency magnetron sputtering of a ceramic target: deposition onto a «cold» platinized silicon and glassceram substrates, followed by high-temperature annealing to obtain islands of the perovskite phase surrounded by a matrix of the low-temperature pyrochlore phase. To study the cross section, a lamella was prepared, the study of the microstructure of which showed that the rotation of the crystal lattice in the perovskite spherulite occurs uniformly throughout the entire thickness, and it is not a manifestation of some near-surface effects. It was found that the rate of rotation of the crystal lattice in spherulites with a radial-radiant structure is approximately two times less than in spherulites with a radially uniform rotation; a model of translational rotation of the crystal lattice with the formation of dislocations and partial relaxation of mechanical stresses is proposed; it is assumed that the lattice rotation velocity is limited by the elasticity limit of the thin film. It is assumed that the Kikuchi image in spherulitic islands consisting of crystalline grains is determined by both the identical growth texture and the orientational correlation of the grains in the plane of the film; an analysis and interpretation of Kikuchi electron channeling lines has been carried out, which makes it possible to determine the orientation of the crystal lattice planes and growth axes in thin films.

Keywords

• thin films of lead zirconate titanate
• spherulites
• radially-radiant microstructure
• electron kikuchi channeling