Preparation of Na-Al-O films by laser chemical vapor deposition

Na-A1-0 films were prepared on AIN substrates by laser chemical vapor deposition at deposition temperatures (T-dep) of 940-1250 K, molar ratios of Na to Al precursors (R-Na/Al) of 0.2-3 and total pressures (P-tot) of 100-800 Pa. Single-phase NaAlO2 films were deposited at T-dep = 940-1080 K, R-Na/Al = 1.5-3 and P-tot = 100-800 Pa. The (110)-oriented gamma-NaAlO2 films showed roof-like grains, whereas the (200)-oriented y-NaA102 films had finely faceted grains. Single-phase NaAl6O9.5 formed at T-dep = 1018-1125 K, R-Na/Al = 0.4-3.0 and P-tot = 100-600 Pa NaAl6O9.5 films had (041) orientation with pyramidally and polygonally faceted grains. At T-dep > 1100 K, alpha-Al2O3 films, consisting of polygonally faceted grains, formed. The highest deposition rate was 131 mu m h(-1) for the gamma-NaAlO2 film at T-dep = 986 K, R-Na/Al = 3.0 and P-tot = 200 Pa. (C) 2015 Elsevier B.V. All rights reserved.