Luminescence spectra of ZnAl2O4 : Cr3+ spinel nanopowders

The synthetic ZnAl2O4 spinels doped with Cr3+ ions are prepared from ZnSO4, Al-2 (SO4)(3), and Cr-2(SO4)(3). The spinel single phase is detected from X-ray diffraction. Luminescence properties of Cr3+ in ZnAl2O4 were studied by low temperature luminescence and decay measurements. Four luminescence lines at 14570, 14520, 14460, and 14330 cm(-1) were found to originate from structure distortion and the line at 14175 cm(-1) from chromium pairs. The broad emission band at about 13540 cm(-1) is considered to arise from a new Cr3+ center in ZnCr2O4