SPECTROSCOPIC PROPERTIES OF CHROMIUM-DOPED SRLAALO4 SINGLE-CRYSTALS

Cr3+ ions substitute the Al3+ ions in the crystal structure of SrLaAlO 4 and occupy the tetrahedrally-distorted octahedral sites for which th e energy splitting Delta E between the T-4(2) and (2)E states is about 700 cm(-1). As a result, the luminescence originates on both the T-4( 2) and (2)E states at room temperature. The bandwidth of the zero phon on (2)E-(4)A(2) transition exceeds 100 cm(-1) and is independent of te mperature in the 5-100 K temperature region, indicating strong inhomog eneous broadening. The presence of Cr3+ sites displaying different lum inescence pattern has been evidenced by the results of lifetime and th e excitation spectra measurements. These sites may be inherent in the crystal structure of the compound or else they may be created by imper fections which are abundant in both the doped and undoped crystals.