Complex-oxide Synthesis by Emulsion Combustion Method ( ECM ) Kazumasa Takatori ( ) 1995 237,000 44 21 11 9% 2 2 3 R&D Vol. 32 No. 1 ( 1997. 3 )
Magnetic Permanent magnets, AV tapes, Floppy disks: 3CoFe 2 O 4 Fe 3 O 4, Ba-ferrite, GGG, Mechanical Abrasives: Al 2 O 3, SiC, CeO 2, Cr 2 O 3, SnO 2, ZrO 2 Solid lubricants: MoS 2, BN, Gr Mold: CaSO 4 1/2H 2 O Fillers: Fe 2 O 3, MgO Optical Paints, Printing inks: Fe 2 O 3, Fe 3 O 4, TiO 2, Cr 2 O 3, SiO 2, ZnO, CoO nal 2 O 3, PbCrO 4, BaSO 4, MnO 2, TiO 2 NiO Sb 2 O 5, Cosmetics: TiO 2, SiO 2, CaCO 3, Fluorescents: ZnS(Ag), ZnS(Cu), Y 2 O 2 S(Eu), Y 2 O 3 (Eu), ZnO, UV stabilizers: CeO 2, TiO 2, ZnO Semiconductors: SnO 2, ITO, ReO 3, LaTiO 3, Electric Ceramic powders Thermal Catalytic supports: Al 2 O 3, SiO 2 Fillers:SiO 2, Al 2 O 3, AlN, SiC Medical Pesticides: CaO, Fe 2 O 3 Fertilizers: Ca(OH) 2, MnO 2 Pharmaceuticals: ZnO, SiO 2, CaCO 3, MgO, Bi 2 O 3, Dental pastes: Al 2 O 3, CaCO 3, SiO 2 Chemical Photocatalyst: TiO 2 Catalysts: Zeolite, ZnO, CeO 2, ZrO 2, TiO 2, SnO 2, La 2 O 3, Al 2 O 3, V 2 O 5, MnO 2, CuO, MgO, MoS 2, Battery electrodes: MnO 2, LiCoO 2 Fire retardants: Sb 2 O 5, ZrO 2 Explosives: KNO 3 Ceramic powders used for various purposes. ( ) 1995 ( ) R&D Vol. 32 No. 1 ( 1997. 3 )
( 100nm ) ( ) ( ) ( ) ph ( ) ph ph Fig. 2 Liquid phase synthesis Chemical method Physical method Co-precipitation Alcoxide hydrolysis Hydrothermal Freeze drying Spray pyrolysis Emulsion process Classification of ceramic powder synthesis derived from liquid phase. R&D Vol. 32 No. 1 ( 1997. 3 )
ph Fig. 2 10µm 100µm 1µm W/O ( water in oil ) 1µm ( µm 0.1µm ) 2 ( 0.1µm 10nm ) ( 10nm 1nm ) BET m 2 /g ( BaO 6Fe 2 O 3 ) 1970 R&D Vol. 32 No. 1 ( 1997. 3 )
W/O 3 1 ( ) 10µm 1µm 74% 99%W/O 2 1 210µm 100µm 12 64% 50µm 2µm 10,000 ( ) Comparison of characteristic features of the powder production methods. Method Solid state Gas phase Co-precipi- Hydro- ECM Feature reaction reaction tation thermal Chemical Purity Medium High High High High Constituent distribution Heterogeneous Homogeneous Homogeneous Homogeneous Homogeneous Production cost Low High High High Medium Grain size Coarse Ultrafine Fine Fine Fine Grain size distribution Broad Narrow Narrow Narrow Narrow Examples of Al 2 O 3 SiO 2 ZrO 2 (Y) BaTiO 3 mass production TiO 2 TiO 2 R&D Vol. 32 No. 1 ( 1997. 3 )
3 a) b) c) d) e) f) NOx Powder production process by emulsion combustion method. Atomization Mist particle Oil 2µm Water droplet H 2 O, Me +, Me' ++, Combustion Supersaturation area Fast heating Moderate heating Oxide powder Hollow particle Solid particle Schematic diagram of metal-oxide crystallization from atomized emulsion. R&D Vol. 32 No. 1 ( 1997. 3 )
( Zr ) ( ZrO 2 ) ( ZrTiO 4 ) ZrTiO 4 ( Pb ( Zr, Ti ) O 3 : PZT ) ZrO 2 ( CeO 2 ) ( ZrCl 2 O 8H 2 O ) 2wt% 5 W/O 5µm X ( XRD ) ZrO 2 2 ZrO 2 ZrO 2 (a) ZrO 2 SEM 1µm 2 Zr1mol/l ZrO 2 1/4 2 Fig. 6(b) ZrO 2 XRD ZrCl 2 O 8H 2 O ( TiCl 4 ) ZrO 2 : TiO 2 = 52 : 48 ( ) ( Nb ) 1 % XRD pattern of pure ZrO 2 synthesized by ECM. SEM images of ZrO 2 powders synthesized by ECM at (a) low temperature and (b) high temperature. R&D Vol. 32 No. 1 ( 1997. 3 )
( NbCl 5 ) ZrO 2 XRD ZrTiO 4 2θ = 29 Nb X ZrTiO 4 SEM 2µm 20µm BET 32m 2 /g Nb ZrTiO 4 2 ( PbO ) 40MPa PZT (a) (b)600 C1h XRD SEM XRD PbO ( massicot ) ( litharge ) 2600 C PZT PbO 2µm SEMZrTiO 4 600 C PZT PbO ZrTiO 4 PZT XRD PZT 500 C 600 CX ZrTiO 4 PbO ( Nb 2 O 5 ) PZT 50 C ZrTiO 4 PZT 800 C PZT ( PbTiO 3 ) PbO XRD pattern of ZrTiO 4 synthesized by ECM. SEM images of ZrTiO 4 powders synthesized by spray methods. R&D Vol. 32 No. 1 ( 1997. 3 )
( kp ) kp Fig. 12 XRD patterns of (a) mixed powder and (b) calcined powder at 600 C 1h. Crystalline phases and reaction temperature. SEM images of PbO + ZrTiO 4 mixed powders. Electromechanical coupling factor(kp) and average grain size of PZT ceramics. R&D Vol. 32 No. 1 ( 1997. 3 )
ZrO 2 -CeO 2 1050 C ZrO 2 CeO 2 2 ZrO 2 ZrO 2 ( Oxygen Storage Capacity ) ZrO 2 -CeO 2 XRD Z100 C100ZrO 2 CeO 2 Z8C2 ZrO 2 : CeO 2 = 8 : 2 ( ) ( ZrO(NO 3 ) 2 2H 2 O ) ( Ce(NO 3 ) 6H 2 O ) Z100 C100 C100 XRD c/a ZrO 2 Z100 3ZrO 2 CeO 2 20 % C100 1 CeO 2 20 % CeO 2 30 % Z5C5 SEM TEM 10nm XRD XRD patterns of ZrO 2 /CeO 2 solid solutions. Lattice constant of ZrO 2 -CeO 2 solid solutions synthesized by ECM. R&D Vol. 32 No. 1 ( 1997. 3 )
10nm TEM BaTiO 3 SEM image of C5Z5 powder synthesized by ECM. TEM image of C5Z5 powder synthesized by ECM. XRD crystallite size by of ZrO 2 -CeO 2 solid solution powders prepared by ECM. Raman spectrum of ZrO 2 -CeO 2 solid solutions. ( t: tetragonal, m: monoclinic, c: cubic ) Sample name Crystallite size (nm) Z8C2 Z7C3 Z6C4 Z5C5 Z4C6 Z2C8 C100 6 5 10 4 16 8 ( 410 ) R&D Vol. 32 No. 1 ( 1997. 3 )
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