Luminescence of SrAl2O4:Cr3+

Samples of SrAl2O4 and SrAl2O4:Cr3+ were prepared by mixing the powder materials SrCO3, Al2 O3, and Cr2O3. The crystal structures of the undoped and doped samples were analyzed by X-ray diffraction (XRD) measurements. The diffraction patterns reveal a dominant phase, characteristic of the monoclinic SrAl2O4 compound and another unknown secondary phase, in small amount, for doped samples. The data were fitted using the Rietveld method for structural refinements and lattice parameter constants (a, b, c, and b) were determined. Luminescence of Cr3+ ions in this host is investigated for the first time by excitation and emission spectroscopy at room temperature. Emission spectra present a larger band and a smaller structure associated to the 4T2 (4F) !4 A2 (4F) and 2E (2G) !4 A2 (4F) electronic transitions, respectively. The obtained results are analyzed by crystal-field theory and the crystal-field parameter, Dq, and Racah parameters, B and C, are determined from the excitation measurements.