Abstract
The work presents studies on the microstructure and mesostructure of nanostructured aluminum oxyhydroxide formed as a high porous monolithic material through the surface oxidation of aluminum liquid-metal solution in mercury in a temperature- and humidity-controlled air atmosphere. The methods of X-ray diffraction analysis, thermal analysis, the low temperature adsorption of nitrogen vapors, transmission electron microscopy, small-angle and very small-angle neutron scattering, and small-angle X-ray scattering are used for comprehensive investigation of the samples synthesized at 25 degrees C as well as that annealed at temperatures up to 1150 degrees C. It is found that the structure of the monolithic samples can be described within the framework of a three-level model involving primary heterogeneities (typical length scale of r(c) approximate to 9-19 angstrom), forming fibrils (cross-sectional radius R approximate to 36-43 angstrom and length L approximate to 3200-3300 angstrom) or lamellae (thickness T approximate to 110 angstrom and width W approximate to 3050 angstrom) which, in turn, are integrated into large-scale aggregates (typical size R-c approximate to 1.25-1.4 mu m) with an insignificant surface roughness. It is shown that a high specific surface (similar to 200 m(2)/g) typical for the initial sample is maintained upon its thermal annealing up to 900 degrees C, and it decreases to 100 m(2)/g after heat treatment at 1150 degrees C due to fibrillary agglomeration.