Kinetics of thin-film reactions of nickel oxide with alumina. 2: {l_brace}1{ovr 1}00{r_brace} and {l_brace}1{ovr 1}02{r_brace} reaction couples

Journal Article · Sun Nov 01 04:00:00 EST 1998 · Journal of the American Ceramic Society

OSTI ID:289479

Kotula, P G; Carter, C B ^[1]

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1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Science

The kinetics of the earliest stages of solid-state reactions between epitactic thin films of nickel oxide (NiO) and {l_brace}1{bar 1}00{r_brace}- and {l_brace}1{bar 1}02{r_brace}-oriented single crystals of alumina (Al{sub 2}O{sub 3}) have been studied. The starting reaction geometry consisted of a nickel aluminate (NiAl{sub 2}O{sub 4}) buffer layer 20 nm thick and a NiO overlayer that was 400 nm thick, both of which were grown via pulsed-laser deposition and were epitactic with the substrate. When heated, the reaction layers thickened mainly as the square root of time (i.e., parabolic kinetics) increased, which was indicative of reaction-controlled kinetics via diffusion through the product layer. The activation energy for the reaction was 461 kJ/mol for {l_brace}1{bar 1}00{r_brace} and 464 kJ/mol for the {l_brace}1{bar 1}02{r_brace}; both values are consistent with measurements made previously using thin-film and bulk reaction geometries. A smaller linear component to the kinetics has also been identified. The results of microstructural characterization and marker experiments will also be discussed.

• OSTI ID: 289479
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 11 Vol. 81; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ACTIVATION ENERGY
ALUMINIUM OXIDES
CHEMICAL REACTION KINETICS
DIFFUSION
GRAIN ORIENTATION
NICKEL OXIDES
THIN FILMS