Preparation And Luminescentmechanism Research Of Al₂O₃/Montmorillonite Luminescent Material

Lighting technology, display technology, and optical communication technology have now become an important part in people’s lives; however, the development of those applications highly depends on the study of luminescent material doped with rare earth. Therefore, the luminescent material doped with rare earth which is low-cost, high luminous efficient, chemically stable and durable is the focus of the study. Al2O3features good thermostability, structural stability, and transparency, which can be used as the matrix of luminescent material; while Montmorillonite with lamellar structure composes of a two-layer silica tetrahedron and one-layer Alumina octahedron, and has the distinctive structural features and surface activity because of negative charges between the layers.The synthetictechnology of Al2O3/montmorillonite luminescent materials such as process parameters, luminescence properties, crystal structure and luminescence mechanism were explored. The influencesof the variation type and concentration of the activatoron the emission spectrumwere discussed. The luminescence property was improved by adding different additives, and the luminescence mechanism was analyzed. The experimental results are as follows:1. The synthesis technology of Al2O3/montmorillonite luminescent materials was researched. The best luminescence properties of Al2O3/montmorillonite:Eu2+luminescent material with blue lightcould be achieved when the quality ratio between Al2O3and montmorillonitewas about40:60with5%Eu2+and sinteredat1400℃for2h at the reducing atmosphere. The emission spectrum consisted of a broad peak at380-600nm,corresponding to4f65dâ†'-4f7broadband allowed transition of Eu2+.2. The luminescent properties of Al2O3/montmorilloniteluminescent materials were researched through single-dopingEu2+, Sm3+, Tb3+and Ce3+respectively,as well as co-doping Eu2+-Sm3+,Eu2+-Ce3+and Eu2+-Tb3+.The Eu2+and Tb3+co-doped samples presented the blue light under ultraviolet excitation, the critical distance between Eu2+and Tb3+was calculated to about0.8784nm with radiation resonance energy transfer, belonging to the resonance energy transfer from electric quadrupole to electric quadrupole. The optimum doping concentration was obtained to be5mol%Eu2+and5mol%Tb3+.3. The luminescence performance of material with adding different valence of cations were researched. NaF and Y2O3can be consideredas the flux, K+refers to ion charge compensation, recovered the charge defects in the crystal lattice, Mg2+can reacted with the matrix material and generates a new phase MgAl2O4. The luminous intensity of samples were increased by adding these additives.4. The influences of microwave method and sol-gel method on the synthetics of Al2O3/montmorillonite:Eu2+luminescent material were researched.The best sample was obtained by one-step method of microwavewith high heat for60min.Compared with three kinds of sintering method, the higher luminescent intensity for samples synthesized by solid-state method has been obtain but withlarger grain size, for the microwave method, it has shorter of soaking time and less ofthe energy consumption.