Trace hydrogen in Verneuil-grown corundum and its colour varieties — an IR spectroscopic study
European Journal of Mineralogy Volume 3 Number 6 (1991), p. 971 - 976
published: Dec 19, 1991
manuscript accepted: May 13, 1991
manuscript received: Feb 18, 1991
ArtNo. ESP147050306005, Price: 29.00 €
Abstract IR spectra of Verneuil-grown colourless corundum, rose to deep red ruby, blue, “amethyst”- and “alexandrite”- coloured sapphire show a distinct variability in the region of the OH stretching fundamental. Hydrogen, bonded to oxygen, varies from approximately 1 to 3.5 ppm. Extremely pleochroic and narrow OH bands are centered at 3310, 3230 and 3185 cm-1. The OH dipoles are oriented perpendicular to the c-axis. Assuming vacancies in the cation lattice, OH is coordinated to two Al atoms forming "groups" of face-sharing Al2(OH)O8-double octahedra.