Antiphase ordering and surface phases in lithium aluminate

Antiphase domains are seen in single crystal gamma lithium aluminate (γ -LiAlO2) with 16.7 nm periodicity in the 〈 110 〉 direction. Alternate domains have a 1 2 [001] shift. Beta phase lithium aluminate (Β -LiAlO2) is seen to form on the surface of the as-received wafers with an epitaxial strain limited relationship with the bulk γ phase. The orthorhombic Β phase aligns with the a and b axes (0.528 and 0.630 nm) matching with the tetragonal γ phase's a and c axes (0.5168 and 0.6268 nm). The γ and Β phases are seen to have different etch rates. The Β phase converts back to the γ phase above 450 °C.