Synthesis And Luminescence Properties Of Sm³⁺ Doped Nanoporous Calcia-Alumina System Powders

The objective of this work was to develop a kind of nano-sized powders, which istrivalent samarium (Sm³⁺)-doped12CaO·7Al₂O₃or Sm³⁺-doped12CaO·7Al₂O₃and5CaO·3Al₂O₃mixture powder. In this thesis, analysis had been made about therelationships of composition, structure and optical properties of Sm³⁺-doped12CaO·7Al₂O₃and mixture powder, which were synthesized by the combustion method.The microstructure of Sm³⁺-doped12CaO·7Al₂O₃and mixture powders wasinvestigated by X-ray diffraction （XRD） and Scanning Electron Microscope （SEM）while the optical properties of Sm³⁺-doped12CaO·7Al₂O₃and mixture powders werecharacterized by photoluminescence, photoluminescence excitation, the temperaturedependent luminescence, and so on.The XRD study revealed that the cage structural polycrystalline12CaO·7Al₂O₃powders of single cubic phase and the mix powder were obtained. It demonstrated thatSm³⁺had been incorporated into12CaO·7Al₂O₃lattice site without destroying thelattice structure.The emission spectra show three dominant emission bands in the visible region,one was attributed to the magnetic dipole transition of⁴G_5/2â†'⁶H_5/2centered at565nm,the other was forced electric dipole transition of⁴G_5/2â†'⁶H_7/2centered at599nm, thelast one was form⁴G_5/2â†'⁶H_9/2transition and centered at648nm, respectively, wereobserved. The spectrum consists of many excitation bands of f-f transitions, which areoriginated from different transitions from the ground state6H5/2to the various excitedstates of4f5electronic configurations of the Sm³⁺ions. The most effective excitationwavelength is404nm, just in the near ultraviolet area. Different annealing temperaturecan change the proportion of12CaO·7Al2O in the mixture powder. This method canimprove the luminous intensity of trivalent samarium. This may be relevant to thesymmetry of the matrix powder.Further samples carbon embedded restore the luminescence of samarium ions willcontinue to increase. We believe that the result of electron substitution in the oxygenions in the reduction process in C12A7cage leaving the lattice distortion caused bychanges in its symmetrical structure. This with the near ultraviolet chip of Sm³⁺dopedthe blended powder of12CaO·7Al2O, red-orange light may be used in the production ofwhite LED, display optoelectronic devices.Aluminate material has good thermal stability, the experimentally measured the different temperature emission spectra, Sm³⁺doped the blended powder of12CaO·7Al2O and5CaO·3Al2O with the orange light （599nm） with integral area offitting the draw indicate that the thermal activation energy is200meV. High activationmeans smaller luminescence temperature quenching effect. In addition, the sample withthe good environment affinity and low raw material cost will be its advantage to productlighting use high power LED, other optoelectronic devices widely used in favorableconditions.