Experimental study of structural, surface morphology, optical and luminescence properties of MAl2O4/Al2O3 (M = Co, Ni) composites

The novel alumina-based luminescence material of MAl2O4/Al2O3 (M = Co, Ni) were prepared by a polyacrylamide gel route. Influence of Co/Ni metal salt on the sample morphology, band-gap and luminescence properties were investigated by transmission electron microscopy (TEM), UV-vis spectrophotometer and fluorescence spectrophotometer. The results indicated that the Co/Ni metal salt added to the precursor solution could significantly effects the phase formation process, powder morphology, optical and luminescence properties of the prepared MAl2O4/Al2O3 (M = Co, Ni) composites. The Co metal salt or Ni metal salt introduced to Al2O3 precursor solution reduces the band-gap values and enhances the luminescence properties of MAl2O4/Al2O3 (M = Co, Ni) powders. It is confirmed that the interaction between the intra-band gap defects of CoAl2O4/NiAl2O4 and the oxygen vacancies on the surface of the C/amorphous alumina composite play a specific role for the determination of photoluminescence emission. Compared with the CoAl2O4/Al2O3 composites, the NiAl2O4/Al2O3 composites have a stronger the fluorescence intensity because of the wide band-gap value of NiAl2O4. A new luminescence mechanisms of MAl2O4/Al2O3 (M = Co, Ni) composites have been proposed on the basis of the experimental and computational results.