Beitrag
The mysterious "δ-Al2O3"
Saalfeld, H.; Guse, W.
Neues Jahrbuch für Mineralogie - Abhandlungen Band 163 Heft 1 (1991), p. 159 - 167
14 Literaturangaben
veröffentlicht: Aug 13, 1991
DOI: 10.1127/njma/163/1991/159
ArtNo. ESP154016301010, Preis: 29.00 €
Abstract
Crystal material of (σ-Al2O3 was produced by the skull-melting technique. The crystals were investigated by X-ray and electron diffraction. Single crystals show a deformed spinel lattice with satellite systems. Specially the reflections h,k,l = odd are accompanied by strong satellites where a distinct relationship in the intensity distribution is recognized. Electron diffraction patterns confirm the satellite systems and reveal local areas of superstructures that could not be detected by X-ray methods. HRTEM micrographs show a complex system of domains and vacancies. X-ray Guinier photographs yield spacings of powder lines that are identical with d-values published in literature for “δ-Al2O3”. “δ-Al2O3 is not a phase with a crystal structure of its own but considered as a modulated variant of σ-Al2O3.
Schlagworte
Alumina • spinel-type variants • modulation structures • skull-melting