Effect of Li addition on the formation of Na-β/βʹʹ-alumina film by laser chemical vapor deposition

Abstract Films composed of a mixture of Na-β- and βʹʹ aluminas (β/βʹʹ-alumina) were prepared via laser chemical vapor deposition (CVD) upon the addition of Li. The effect of the Li source gas on the phase formation, microstructure and deposition rates of the β/βʹʹ-alumina films was investigated. The Na-β/βʹʹ-alumina films were formed at a Li/Al precursor supply ratio ( R Li/Al ) of 0.1–1.0 within a deposition temperature ( T dep ) range of 1100–1220 K. The Na-β/βʹʹ-alumina phase was exclusively formed at T dep =1165–1185 K and R Li/Al =0.1–0.5, whereas α-Al 2 O 3 (with minor amounts of LiAlO 2 and LiAl 5 O 8 ) was predominantly observed at T dep >1223 K and R Li/Al >1.0. The Na-β/βʹʹ-alumina films were composed of polygonal facets in sizes of several hundred nanometers with a columnar cross section. The deposition rate of the Na-β/βʹʹ-alumina film was 60 µm h −1 .