Low iron, pale blue natural and synthetic sapphire samples were studied by low temperature absorption and luminescence spectroscopy. For comparison, a bicolour pink and blue corundum from Vietnam was also considered. From radioluminescence and photoluminescence excitation spectra of both Cr <sup>3+</sup> and Ti<sup>3+</sup>, experimental evidence was obtained for attributing an absorption band at 17 500cm<sup>-1</sup>, currently interpreted as intervalence charge transfer, to overlapping crystal field transitions of Cr<sup>3+</sup> and Ti<sup>3+</sup>. An important role was also proposed for Cr<sup>2+</sup>; indeed, it is possible to propose that the colour of pale blue sapphires is mainly determined by chromium in its two valence states while Ti<sup>3+</sup> and Fe<sup>3+</sup> have a minor role. © IOP Publishing Ltd.
Fontana, I., LE DONNE, A., Palanza, V., Binetti, S., Spinolo, G. (2008). Optical Spectroscopy study of Type 1 natural and synthetic sapphires. JOURNAL OF PHYSICS. CONDENSED MATTER, 20(12) [10.1088/0953-8984/20/12/125228].
Optical Spectroscopy study of Type 1 natural and synthetic sapphires
LE DONNE, ALESSIA;BINETTI, SIMONA OLGA;SPINOLO, GIORGIO MARIO
2008
Abstract
Low iron, pale blue natural and synthetic sapphire samples were studied by low temperature absorption and luminescence spectroscopy. For comparison, a bicolour pink and blue corundum from Vietnam was also considered. From radioluminescence and photoluminescence excitation spectra of both Cr 3+ and Ti3+, experimental evidence was obtained for attributing an absorption band at 17 500cm-1, currently interpreted as intervalence charge transfer, to overlapping crystal field transitions of Cr3+ and Ti3+. An important role was also proposed for Cr2+; indeed, it is possible to propose that the colour of pale blue sapphires is mainly determined by chromium in its two valence states while Ti3+ and Fe3+ have a minor role. © IOP Publishing Ltd.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.