Atomic-resolution analysis for the effects of heat treatment temperatures on the growth of chemically-ordered regions in Pb(Mg1/3Nb2/3)O3 thin films

Abstract

This paper describes growth behaviors of chemically-ordered regions (CORs) in Pb(Mg1/3Nb2/3)O3 (PMN) epitaxial thin films. The films are crystalized at 650°C, which corresponds to about half of the crystallization temperature of bulk crystals. We obtained PMN epitaxial thin films with high crystallinity by using a metallo-organic decomposition (MOD) process. According to our atomic-resolution analysis using HAADF-STEM images, it is shown that CORs in PMN epitaxial thin films grow by nucleation of small clusters whose sizes are 1 to 2 nm on each side of habit plane, {100} and {110}. In addition, post-annealing process at 700 or 800°C causes growth of CORs. The growth mechanism of CORs is not by the expansion of each cluster but by the nucleation of new clusters. After post-annealing at high temperatures, CORs join with each other on their habit plane and made a network along 〈100〉, 〈110〉 and 〈112〉 direction.