Influence of impurities on Cr3+ luminescence properties in Brazilian emerald and alexandrite
Ollier, Nadège; Fuchs, Yves; Cavani, Olivier; Horn, Adolf Heinrich; Rossano, Stéphanie
European Journal of Mineralogy Volume 27 Number 6 (2015), p. 783 - 792
published: Dec 1, 2015
ArtNo. ESP147052706006, Price: 29.00 €
Emerald and alexandrite, the chromiferous varieties of beryl, Be3 Al2 [Si6 O18], and chrysoberyl, BeAl2 O4, respectively, are, as gems, of high economical and technological interest. The Cr3+ properties in natural beryl and chrysoberyl samples have been studied by mainly photoluminescence technique and electron paramagnetic resonance (EPR) as a function of Cr content (50–11370 ppm) as well as impurities, such as Fe and V. In emeralds, the Cr3+ crystal field value is linked to the Cr content and decreases when Cr increases. In chrysoberyl with low Cr content, the vanishing of Cr3+ emission from Cr3+ ions located on the inversion-symmetry site suggests a competition between Cr and V regarding chemical substitution. The Fe3+ ion substitutes efficiently on the mirror-symmetry site, with a strong impact on the Cr3+ lifetime on this site.