Premium
“Amorphous” Precursors of α‐Al 2 O 3 : An Electron Optical Study
Author(s) -
Brand P.,
Dietzmann P.
Publication year - 1992
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170270420
Subject(s) - corundum , amorphous solid , diaspore (botany) , aluminium , decomposition , materials science , electron diffraction , mineralogy , electron , diffraction , aluminium oxide , crystallography , chemical engineering , chemical physics , chemistry , optics , metallurgy , physics , organic chemistry , biological dispersal , population , demography , seed dispersal , quantum mechanics , sociology , engineering
Basic aluminium chloride gels are thermally decomposed into X‐ray amorphous products. Corundum begins to crystallize in them about 400 °C on certain conditions. Electron optical examinations on powders of corundum‐forming gels and of their decomposition products show in an essential part aggregates of sheetlike components as powder particles. These have sharp electron diffraction patterns. The interpretation of diagrams proves the existence of two different structures with similar lattices, which are evidently related to those of diaspore and corundum. A defect structure is to be assumed for the corundum crystals formed.