Antiphase ordering and surface phases in lithium aluminate

Abstract

Antiphase domains are seen in single crystal gamma lithium aluminate (gamma-LiAlO(2)) with 16.7 nm periodicity in the \u3c 110 \u3e direction. Alternate domains have a 1/2 [001] shift. Beta phase lithium aluminate (beta-LiAlO(2)) is seen to form on the surface of the as-received wafers with an epitaxial strain limited relationship with the bulk gamma phase. The orthorhombic beta phase aligns with the a and b axes (0.528 and 0.630 nm) matching with the tetragonal gamma phase\u27s a and c axes (0.5168 and 0.6268 nm). The gamma and beta phases are seen to have different etch rates. The beta phase converts back to the gamma phase above 450 degrees C