Spectroscopy ofCr3+andCr4+ion

Luminescence properties of a new red long-lasting phosphor: Mg2SiO4:Dy3+, Mn2+

“…1b) consists of a broad band at 650 nm. The emission band can be fitted by two Gaussian peaks at 645 and 723 nm, which should be attributed to the transitions of Mn 2+ ions occupying two nonequivalent Mg 2+ sites, mirror symmetric octahedron (M 2 ) and inversion symmetric octahedron (M 1 ), respectively [8]. The similar emission band was also observed and investigated in Mg 2 SiO 4 :Mn 2+ samples prepared by sol-gel method [7].…”

Investigation on the valence of Cr ions in LiAlO2

“…The first excited state of the 3d 2 configuration is either 1 E or 3 T 2 , which are expected to lie above B6000 cm À1 as they do in Cr 4+ :forsterite [6,7] and Cr 4+ :garnets [8,9]. The EPR results suggest trivalent Cr ions with a 3d 3 configuration.…”

New laser crystals for the generation of ultrashort pulses

“…Finally, the Cr 4+ doping in YAG and in forsterite often leads to severe problems because of a strong competition between Cr 4+ and Cr 3+ . In fact due to the existence of two different site geometries: octahedral (favoring Cr 3+ ) and tetrahedral (favoring Cr 4+ ), chromium ions can be found in both 4+ and 3+ oxidation states, which frustrates the Cr 4+ doping and modifies the spectral properties of the crystal [16].…”