The room-temperature reaction of lithium hydroxide with aluminum hydroxide (bayerite) in the ratio of 1:2 produces lithium dialuminate, LiA12(OH),*2H20. Rietveld refinement of X-ray and neutron powder diffraction patterns indicate that the structure is composed of [LiAlZ-(OH),]+ layers separated by water molecules and hydroxide ions. Disorder in the stacking sequence leads to indexing the diffraction pattern on a hexagonal cell (a = 5.0972(3) A, c = 7.5524(9) A X 3n layers); however, the structure is better described by a C-centered monoclinic cell with the constraints the b = a d 3 and cos / 3 = -a/3c ( a = 5.097 A, b = 8.829 A, c = 7.741 A, and /3 = 103.0'). The diffraction patterns were refined using a model of up to 54 layers (-400 A). The layer stacking vector, which defines the angle between layers, is less than expected based on the position of the diffraction peaks. The structural complexities present in lithium dialuminate have their origins in the conditions of synthesis and the layered nature of the material.

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The stress-temperature relationship of silica spin-on-glass thin films on silicon wafers was studied. Upon heating, the stress-temperature curves showed a dramatically increasing slope when the temperature of the film was greater than 340°C. At 450°C, a significant, irreversible change in the stress of the film was observed. This change in stress was correlated with an increase in film electron density and a decrease in film thickness. The observed thermally activated stress-relaxation behavior was interpreted in terms of reflow of the glassy hydrogen-silsesquioxane-based material.

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