In-situ TEM crystallization of anorthite-glass films on α-Al<inf>2</inf>O<inf>3</inf>

Anorthite-glass films have been grown by pulsed-laser deposition on single-crystal α-Al2O3 substrates which were pre-thinned to electron transparency. The glass films were crystallized in the transmission electron microscope (TEM), which allowed direct observation and video-recording of the crystallization process. Crystallization of these films in the TEM resulted in the formation of hexagonal and orthorhombic anorthite. The orthorhombic phase was the predominant product of glass films grown at elevated substrate temperatures and displayed strong epitaxy with the underlying substrate. In contrast, the hexagonal phase was the major constituent of films grown at ambient substrate temperature and displayed no clear epitaxy with the substrate. The differences in degree of epitaxy and phase structure may be evidence of ordering at the original glass/oxide interface.