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Phosphor nanoparticles (e.g., SrTiO3:Pr,Al and (Y,Gd)3Al5O12:Ce) were prepared using a conventional spray pyrolysis method in conjunction with a polymer-assisted heat treatment (annealing). The effects of spray/annealing temperatures, polymer type, polymer concentration, and salt addition on the morphology, crystallinity, particle/crystal size, and the photoluminescence intensity of as-prepared as well as annealed phosphor particles were investigated. The results showed that the nanocrystal growth of as-prepared-sprayed submicrometer particles was improved and that the nanocrystal networks disintegrate into nanoparticles when polymer or salt solutions are added during the heat-treatment process. The additional combustion heat and gas evolution during the thermal reaction of polymer appear to be the main reasons for this. On the contrary, only compacted agglomerated particles rather than dispersed nanoparticles were found in the case of annealing without polymer/salt addition. [ABSTRACT FROM AUTHOR]

A europium doped ZnO (ZnO:Eu) particle was directly synthesized by the spray pyrolysis method. The crystal structure of samples was designated by the europium ion and the synthesis temperature. We identified the coexistence of Eu2+ and Eu3+ ions in the as prepared ZnO, which was strongly influenced by the doping concentration and the synthesis temperature. With addition of a 0.5mol% concentration of europium ions, only the Eu2+ ion existed in particles, while both Eu2+ and Eu3+ ions existed in sample using 1mol% or higher concentration of europium ions. Changing the wavelength of the excitation source, we also found that both the blue and red luminescence can be obtained. [Copyright &y& Elsevier]

Abstract: The surface of BaTiO3 particles was modified by 3-glycidoxypropyltrimethoxysilane (GPTMS) to attach epoxy groups on them and to improve their compatibility with epoxy resin. First, in order to analyze the effect of solvents on the degree of surface modification of BaTiO3 particles, the surfaces of BaTiO3 particles were modified with GPTMS in water, ethanol, and xylene at 80°C. FT-nIR analysis showed that due to the ring-opening reaction, the epoxy group on BaTiO3 particles was reduced after surface modification in ethanol and disappeared after surface modification in water. In contrast, when BaTiO3 particles were modified in xylene, the epoxy groups remained. Then, the relationships among these surface structure differences, viscosity of BaTiO3/epoxy/N-methyl-2-pyrrolidinon (NMP) suspensions, the surface morphologies of BaTiO3/epoxy composites, and the dielectric properties of BaTiO3/epoxy composites were investigated. While there was no relationship between the suspension viscosity and the dielectric properties of BaTiO3/epoxy composites, a BaTiO3/epoxy composite with a smooth surface and high dielectric properties was obtained when the BaTiO3 surface was modified in xylene and the epoxy groups were effectively retained on the surface. [Copyright &y& Elsevier]

Abstract: The deposition monolayers of L10 FePt nanoparticles via an electrospraying method and the magnetic properties of the deposited film were studied. FePt nanoparticles in a size of around 2.5nm in diameter, prepared by a liquid process, were used as a precursor. The size of the deposited particles can be controlled up to 35nm by controlling the sprayed droplet size that is formed by adjusting the precursor concentration and the precursor flow rate. The droplets were heated in a tubular furnace at a temperature of up to 900°C to remove all organic compounds and to transform the FePt particles from disordered face centered cubic to an ordered FCT phase. Finally, the particles were deposited in the form of a monolayer film on a silicon substrate by electrostatic force and characterized by scanning electron microscopy. The monolayer of particles was obtained by the high charge on particles obtained during the electrospraying process. The magnetic properties of the monolayer were investigated by magneto-optic Kerr effect measurements. Coercivity up to 650Oe for a film consisting of 35nm L10 FePt nanoparticles was observed after heat treatment at a temperature of 800°C. [Copyright &y& Elsevier]