A New Method of Preparing θ-Alumina and the Interpretation of Its X-Ray-powder Diffraction Pattern and Electron Diffraction Pattern

Highly crystallized θ-alumina was obtained by a two-step treatment, by hydrothermal and thermal treatment, of η-alumina. Its X-ray-powder diffraction pattern was interpreted based on the structure of θ-gallia, and least-squares refinements were carried out. The electron diffraction pattern of θ-alumina from boehmite was also interpreted, and the directional relations between the phases were established.