Research on the Morphology of Lithium Aluminate Films Prepared by Laser Chemical Vapor Deposition

Abstract

The Li-Al-O system has three compounds of LiAl 5 O 8 , LiAlO 2 and Li 5 AlO 4 . Among them, LiAlO 2 attracts increasing attention as a potential substrate for growing GaN semiconductor due to low lattice mismatch and removability. It is also of interest as a solid tritium breeding material to produce tritium fuel by the nuclear reaction of Li(n, a)T in a fusion reactor, since LiAlO 2 shows high-temperature stability and good compatibility with structural materials under irradiation with neutrons. Additionally, LiAlO 2 is thermochemically stable even at 973 K so that it is usually used as the support for the polymer electrolyte to form the diaphragm transporting CO 32-in molten carbonate fuel cells (MCFC). In this paper, (110) and (004)-oriented γ -LiAlO 2 films were prepared on poly-crystalline AlN substrates by laser chemical vapor deposition atdeposition temperature (T dep ) of 1000–1300 K, molar ratio of Li/Al (R Li/Al ) of 1.0–10 and lowtotal pressure (P tot ) of 100–200 Pa. The (004)-oriented γ -LiAlO 2 films consisted of pyramidal grains with acolumnar structure while (110)-oriented γ -LiAlO 2 films showed granular and polygonal column. The deposition rate of γ -LiAlO 2 films reached to 60–90 µ m h -1 .