Synthesis And Characteristics Of Sialon Nano-scale Phosphors And Montmorillonite Nano Sheets

As a novel class of inorganic phosphors, oxynitride and nitride luminescent materials have received considerable attention because of their excellent properties, high luminous efficacy, high chromatic stability and good thermal and chemical stabilities et al. In general, oxynitride and nitride luminescent materials were prepared by hot-pressing sintering or gas-pressing sintering process using high-purity nitride as starting materials. Moreover, their sintering system demands harsh reaction conditions. In this thesis, we studied the carbothermal synthesis of Rare-earth-doped Sialon ceramics. Eu2+ Doped Ca-α-SiAlON phosphor and Ce3+ Doped Ca-α-SiAlON phosphor have been synthesized from SiO2,Al2O3, CaCO3, Eu(NO3)3, Ce(N03)3·6H2O,carbon powders by carbothermal reduction-nitridation (CRN). We studied the reaction mechanism of CRN process on the basis of various phase at different soaking time while sintering Eu2+Doped Ca-α-SiAlON sample in 1390℃. In addition, Eu2+ Doped Ca-α-SiAlON was synthesized at 1500℃or 1550℃. Ce3+ Doped Ca-α-SiAlON was synthesized at 1500℃for 3 h. Eu2+ dopedβ-sialon(z=1,2,3) ultrafine powders were synthesized by carbothermal reduction-nitridation (CRN) technique. The precursors ofβ-sialon was synthesized from SiO2, AlCl3·6H2O,Eu(NO3)3,ammonia solution,carbon powders by the sol-gel method. The relations between luminescence properties and z value of Eu2+ dopedβ-sialon were studied. Using X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM), transmission electron microscopy (TEM). fluorescent spectrophotometer, the phase, morphology, structure, size and luminescence properties of Eu2+dopedβ-sialon phosphor were studied.Montmorillonite mainly consist of hydrated aluminum silicate. Montmorillonite has particular properties and many practical applications, because of their special crystal structure.In this thesis, cetyltrimethylammonium bromide (CTAB), tetrabutylammonium hydroxide (TBAOH), sodium dodecyl sulfate (SDS) surfactants as intercalation agent, the organo-montmorillonite was prepared under various conditions. Montmorillonite and organo-montmorillonite as raw materials,the corresponding surfactant as stabilizer, montmorillonite nanosheet is prepared by microwave irradiation.Nanosheets of exfoliated montmorillonite platelets dispersed in distilled water have been synthesized from natural montmorillonite and anion surfactants sodium laurylsulfonate(SDS) by vigorous stirring and heating for few hours. Using X-ray Diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR), interlayer spacing of organo-montmorillonite, Organic functional groups were studied. Using zeta potential analyzer, transmission electron microscopy (TEM), zeta potential and structure of nanosheet were studied.Using UV-visible absorption spectroscopy, concentration of montmorillonite nanosheets sol were compared when montmorillonite nanosheets were prepared by microwave irradiation oreano-montmorillonite and montmorillonite as raw materials.