The surface of particle can be tailored to get specific physical, optical, electronic, chemical, and biomedical properties by coating a thin film of material on the surface of the particles while the core particle is given new functions maintaining its fundamental physical properties.
In order to prepare the magnetically separable photocatalyst, $TiO_2/SiO_2$ coated $NiFe_2O_4$ was prepared by a continuous multi-step spray pyrolysis process. This new type photocatalyst combined the magnetic property of core part and catalytic property of shell part of particle. Submicron size $NiFe_2O_4$ particle was prepared by ultrasonic spray pyrolysis and titania nano particle was coated continuously. There are no impurities between coated titania layer and core material, $NiFe_2O_4$ under the high reaction temperatures. Prepared photocatalyst showed good photoactivity compared with commercial photocatalyst ($Degussa^＼textregistered P-25$) and titania and silica double layer coated $NiFe_2O_4$ particle had more enhanced photoactivity.
To give the hydrophobicity on bare silica surface, fumed silica surface was modified with Octhytriethoxysilane (OTES). From the coating process, surface property of silica powder was easily changed. We investigated an aerosol spray reactor method for modifying the hydrophobicity of silica particle. The aerosol spray reactor method has all the advantages of liquid-phase process, while it produces agglomeration-free particle at lower operating cost than the gas-phase process. Hydrophobicity of the modified particles was compared with the silica particle modified by liquid-phase process and gas-phase process. Hydrophobicity of commercial silica ($Aerosil^＼textregistered R812, Degussa$) was also measured as a reference.
In order to non-oxide coating on ceramic powder, lithium-salt was coated on fumed silica surface and its electrical property was measured. Lithium-salt-coated silica was used as new type lithium rechargeable polymer electrolyte for improving the ion conductivity of Single ion conductor (SIC). Nano-size lithium coated silica particles were prepared by the spray pyrolysis. The ion conductivity of the prepared electrolyte was changed with different reaction conditions and precursor types. The measured maximum ion conductivity at room temperature was $4 ＼times10^{-4}[S/cm]$, which is higher than the reported ion conductor range of solid ion conductivity at room temperature, $10^{-5}[S/cm]$.
Hollow nano size particle is attracting much attention because of its maximized surface area for the photocatalytic activities and the characteristic optical property caused by the high refractive index difference between shell and hollow inner space. However, formerly introduced hollow particle fabrication methods were complex and much time consuming processes. In order to prepare hollow particle, ceramic-coated polymer particle was prepared and templated for removing core polymer part. In this study, nano-sized hollow particle was prepared by using salt-assisted spray pyrolysis. Salt was used as aggregation controlling agent, and nano-sized PS (Poly-Styrene) particle was used as templates in gas-phase reactor. Compare to the other liquid-phase processes for hollow particle fabrication, Salt-Assisted Spray Pyrolysis Process was able to reduce the significant amount of pollutants, like as toluene, for chemical decomposition of PS.
