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Yun Chan Kang - One of the best experts on this subject based on the ideXlab platform.
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ultrasonic Spray Pyrolysis for air stable copper particles and their conductive films
Acta Materialia, 2021Co-Authors: Dae Soo Jung, Hye Young Koo, Seung Bin Park, Sung Eun Wang, Yun Chan KangAbstract:Abstract Copper (Cu) particles are key components in metal pastes and inks used for conductive electrodes in electronic circuits printed by various methods. However, Cu particles typically suffer from severe oxidation in air, imposing a significant challenge in handling copper particles in manufacturing processes. In this study, ultrasonic Spray Pyrolysis was adopted to generate a large quantity of Cu particles coated with barium borosilicate (BBS) glass to overcome this chronic oxidation issue, as well as to develop stable conductive films. The Spray Pyrolysis process is simple, because the copper and glass materials spontaneously segregate into the core and shell of each particle, respectively, to form core-shell-structured BBS-coated Cu (Cu@BBS) particles. The glass surface layers confer substantial oxidation resistance to the copper particles, as evidenced by analyses after long-term exposure to air. The thin glass layers serve as a sintering promoter and inorganic binder; thus, highly dense conductive copper films with good adhesion to the substrates were formed after sintering. The film obtained from the Cu@BBS particles exhibited resistivities of 2.01 μΩ•cm. The Cu@BBS particles introduced herein are readily applicable in various industrial processes where Spray Pyrolysis has long been established.
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synthesis of hollow cobalt oxide nanopowders by a salt assisted Spray Pyrolysis process applying nanoscale kirkendall diffusion and their electrochemical properties
Physical Chemistry Chemical Physics, 2015Co-Authors: Jung Sang Cho, Jong Hwa Kim, Yun Ju Choi, Yun Chan KangAbstract:A new concept for preparing hollow metal oxide nanopowders by salt-assisted Spray Pyrolysis applying nanoscale Kirkendall diffusion is introduced. The composite powders of metal oxide and indecomposable metal salt are prepared by Spray Pyrolysis. Post-treatment under a reducing atmosphere and subsequent washing using distilled water produce aggregation-free metal nanopowders. The metal nanopowders are then transformed into metal oxide hollow nanopowders by nanoscale Kirkendall diffusion. Co3O4 hollow nanopowders are prepared as first target materials. A cobalt oxide–NaCl composite powder prepared by Spray Pyrolysis transforms into several Co3O4 hollow nanopowders by several treatment processes. The discharge capacities of the Co3O4 nanopowders with filled and hollow structures at a current density of 1 A g−1 for the 150th cycle are 605 and 775 mA h g−1, respectively. The hollow structure formed by nanoscale Kirkendall diffusion improves the lithium-ion storage properties of Co3O4 nanopowders.
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design of particles by Spray Pyrolysis and recent progress in its application
ChemInform, 2012Co-Authors: Dae Soo Jung, Seung Bin Park, Yun Chan KangAbstract:Spray Pyrolysis is a promising aerosol process to produce “designer particles” of precisely controlled morphology with decorations on surfaces or inside particles. Need of precise control of properties has sparked researches on aerosol process that may replace conventional processes such as solid state reaction process or liquid precipitation method. However, productivity is the biggest obstacle in the development of a commercial scale process because the aerosol process is essentially operated at low particle concentration compared to liquid phase processes. In this review, by reviewing publications for the last 10 years we discuss how researchers on Spray Pyrolysis circumvent this inherent limitation of the aerosol process. First, the process of particle design by Spray Pyrolysis is introduced. Some key criteria are explained for selecting each component of Spray Pyrolysis: precursor, additive, carrier gas, heat source, and reactor type. Second, key contributions of major groups in Korea, Japan, Europe, and America are described. Third, some of named processes to overcome productivity of Spray aerosol process are introduced. Fourth, applications of Spray Pyrolysis to materials related to alternative energy, environmental cleaning, information processing and display, and biomaterials are considered. Finally, future prospects of Spray Pyrolysis are discussed along with current standing issues for further progress of Spray Pyrolysis.
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nanosized limn2o4 powders prepared by flame Spray Pyrolysis from aqueous solution
Journal of Power Sources, 2011Co-Authors: Jung Hyun Kim, Yun Chan Kang, Hye Young Koo, Jong Heun LeeAbstract:Abstract LiMn2O4 powders have been directly prepared by flame Spray Pyrolysis from an aqueous Spray solution of the metal salts. The powders prepared at a low fuel gas flow rate (3 L min−1) comprise particles with a bimodal size distribution, i.e., submicron- and nanometer-sized particles, and have crystal structures of LiMn2O4 and Mn3O4 phases. However, the powders prepared at a high fuel gas flow rate (5 L min−1) comprise nanometer-sized particles and have pure crystal structure of LiMn2O4 phase. The powders comprising nanosized particles are well crystallized, and the particles have a polyhedral structure. The mean particle size of these powders is 27 nm. The powders prepared directly by flame Spray Pyrolysis comprise nanosized particles and have the pure crystal structure of LiMn2O4, irrespective of the amount of excess lithium in the precursor solution. The initial discharge capacities of these powders increase from 91 to 112 mAh g−1 when the amount of excess lithium is increased from 0% to 30% of the stoichiometric amount. The optimum amount of excess lithium required to prepare LiMn2O4 powders with nanosized particles and the maximum possible initial discharge capacity is 10%.
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gd2o3 eu phosphor particles prepared from Spray solution containing boric acid flux and polymeric precursor by Spray Pyrolysis
Optical Materials, 2006Co-Authors: Dae Soo Jung, Seung Kwon Hong, Hyo Jin Lee, Yun Chan KangAbstract:Abstract Micron size Gd2O3:Eu phosphor particles with spherical shape and dense morphology were prepared from Spray solution containing boric acid, citric acid and polyethylene glycol by Spray Pyrolysis. Boric acid used as flux material was effective in improving the photoluminescence intensity of micron size Gd2O3:Eu phosphor particles prepared by Spray Pyrolysis. Boric acid did not affect on the morphology of the phosphor particles prepared from Spray solution containing citric acid and polyethylene glycol after post-treatment at high temperature. The optimum content of boric acid in the preparation of Gd2O3:Eu phosphor particles from Spray solution containing polymeric precursors by Spray Pyrolysis was 1 wt.%. The optimum post-treatment temperature of Gd2O3:Eu phosphor particles showing the maximum photoluminescence intensity was 1050 °C. The Gd2O3:Eu phosphor particles post-treated at 1050 °C had complete spherical shape, non-aggregation characteristics and high crystallinity. The photoluminescence intensity of the Gd2O3:Eu phosphor particles prepared from Spray solution containing polymeric precursors and boric acid flux was 149% of the phosphor particles prepared from Spray solution without polymeric precursor and boric acid flux.
Kikuo Okuyama - One of the best experts on this subject based on the ideXlab platform.
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investigation on the correlations between droplet and particle size distribution in ultrasonic Spray Pyrolysis
Industrial & Engineering Chemistry Research, 2008Co-Authors: Weining Wang, Agus Purwanto, Wuled I Lenggoro, Kikuo Okuyama, And Hankwon Chang, Hee Dong JangAbstract:In this study, the measurement of droplet size distribution by means of a laser diffraction technique in ultrasonic Spray Pyrolysis was investigated. Effects of precursor temperature, Spray volume rate, carrier gas flow rate, and physicochemical properties of precursors were analyzed in detail. The results showed that the mean size of precursor droplets decreased with increasing precursor temperature, concentration, and addition of alcohol, while it increased with increasing Spray volume rate and carrier gas flow rate. Bimodal droplet size distribution was observed probably due to droplet coagulation effect. A cyclone or an impactor was used to control the droplet size distribution. Uniform droplets were obtained using a cyclone that removed large droplets. For comparison, Spray Pyrolysis of salt aqueous solutions, such as ZrO(NO3)2 and Ni(NO3)2, were also conducted. Particle size distribution of the Spray pyrolyzed powders was analyzed using scanning electron microscopy. The results showed that the parti...
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investigation on the correlations between droplet and particle size distribution in ultrasonic Spray Pyrolysis
Industrial & Engineering Chemistry Research, 2008Co-Authors: Weining Wang, Agus Purwanto, Wuled I Lenggoro, Kikuo Okuyama, And Hankwon Chang, Hee Dong JangAbstract:In this study, the measurement of droplet size distribution by means of a laser diffraction technique in ultrasonic Spray Pyrolysis was investigated. Effects of precursor temperature, Spray volume rate, carrier gas flow rate, and physicochemical properties of precursors were analyzed in detail. The results showed that the mean size of precursor droplets decreased with increasing precursor temperature, concentration, and addition of alcohol, while it increased with increasing Spray volume rate and carrier gas flow rate. Bimodal droplet size distribution was observed probably due to droplet coagulation effect. A cyclone or an impactor was used to control the droplet size distribution. Uniform droplets were obtained using a cyclone that removed large droplets. For comparison, Spray Pyrolysis of salt aqueous solutions, such as ZrO(NO3)2 and Ni(NO3)2, were also conducted. Particle size distribution of the Spray pyrolyzed powders was analyzed using scanning electron microscopy. The results showed that the parti...
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synthesis of single crystalline zno nanoparticles by salt assisted Spray Pyrolysis
Journal of Nanoparticle Research, 2003Co-Authors: Camellia Panatarani, Wuled I Lenggoro, Kikuo OkuyamaAbstract:LiNO3 was used as a shield in the preparation of single crystalline ZnO particles by a Spray Pyrolysis process in order to prevent agglomeration and enhance the crystallinity of the ZnO. LiNO3 was added to a precursor solution of zinc acetate dihydrate prior to its atomization by means of an ultrasonic transducer. Agglomerate-free particles having a mean particle size of 26 nm were successfully obtained after washing the product. X-ray diffractometry, field-emission scanning electron micrograph and transmission electron micrograph data indicate that the size and morphology of ZnO were strongly influenced by the operating temperature used and the residence time of the particle in the reactor.
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synthesis of lapo4 ce tb phosphor particles by Spray Pyrolysis
Materials Letters, 2001Co-Authors: Wuled I Lenggoro, Kikuo Okuyama, Bin Xia, Hiroaki Mizushima, Naoto KijimaAbstract:Abstract Spray Pyrolysis method was applied to prepare submicron LaPO4:Ce,Tb phosphor particles. The product characteristics such as photoluminescence, crystallinity, and particle morphology were investigated under various preparation conditions and compared with those of commercial ones. The prepared powders showed 543-nm green emission characteristics. The maximum photoluminescence intensity was obtained at 1550°C.
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yag ce phosphor particles prepared by ultrasonic Spray Pyrolysis
Materials Research Bulletin, 2000Co-Authors: Yun Chan Kang, Wuled I Lenggoro, Seung Bin Park, Kikuo OkuyamaAbstract:Abstract Spray Pyrolysis was applied to the preparation of fine YAG:Ce phosphor particles. The characteristics of particles such as crystallinity, morphology, and photoluminescence were investigated. Phase-pure YAG:Ce particles with high crystallinity were obtained after annealing at lower temperatures than those of conventional preparation processes. The mean size of the particles increased from 0.46 to 1.2 μm when the overall solution concentrations were changed from 0.03 to 1 mol/L. The YAG:Ce particles annealed at 1300°C were nonaggregated and spherical. The particles absorbed excitation energy in the range 403–510 nm, and the maximum excitation wavelength was near 470 nm. The YAG:Ce particles showed broad emission peaks in the range 480–650 nm and had maximum intensity at 528 nm. The photoluminescence intensity of the particles increased monotonically with increasing annealing temperature and showed the maximum value at 1 at% Ce.
Wuled I Lenggoro - One of the best experts on this subject based on the ideXlab platform.
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investigation on the correlations between droplet and particle size distribution in ultrasonic Spray Pyrolysis
Industrial & Engineering Chemistry Research, 2008Co-Authors: Weining Wang, Agus Purwanto, Wuled I Lenggoro, Kikuo Okuyama, And Hankwon Chang, Hee Dong JangAbstract:In this study, the measurement of droplet size distribution by means of a laser diffraction technique in ultrasonic Spray Pyrolysis was investigated. Effects of precursor temperature, Spray volume rate, carrier gas flow rate, and physicochemical properties of precursors were analyzed in detail. The results showed that the mean size of precursor droplets decreased with increasing precursor temperature, concentration, and addition of alcohol, while it increased with increasing Spray volume rate and carrier gas flow rate. Bimodal droplet size distribution was observed probably due to droplet coagulation effect. A cyclone or an impactor was used to control the droplet size distribution. Uniform droplets were obtained using a cyclone that removed large droplets. For comparison, Spray Pyrolysis of salt aqueous solutions, such as ZrO(NO3)2 and Ni(NO3)2, were also conducted. Particle size distribution of the Spray pyrolyzed powders was analyzed using scanning electron microscopy. The results showed that the parti...
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investigation on the correlations between droplet and particle size distribution in ultrasonic Spray Pyrolysis
Industrial & Engineering Chemistry Research, 2008Co-Authors: Weining Wang, Agus Purwanto, Wuled I Lenggoro, Kikuo Okuyama, And Hankwon Chang, Hee Dong JangAbstract:In this study, the measurement of droplet size distribution by means of a laser diffraction technique in ultrasonic Spray Pyrolysis was investigated. Effects of precursor temperature, Spray volume rate, carrier gas flow rate, and physicochemical properties of precursors were analyzed in detail. The results showed that the mean size of precursor droplets decreased with increasing precursor temperature, concentration, and addition of alcohol, while it increased with increasing Spray volume rate and carrier gas flow rate. Bimodal droplet size distribution was observed probably due to droplet coagulation effect. A cyclone or an impactor was used to control the droplet size distribution. Uniform droplets were obtained using a cyclone that removed large droplets. For comparison, Spray Pyrolysis of salt aqueous solutions, such as ZrO(NO3)2 and Ni(NO3)2, were also conducted. Particle size distribution of the Spray pyrolyzed powders was analyzed using scanning electron microscopy. The results showed that the parti...
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synthesis of single crystalline zno nanoparticles by salt assisted Spray Pyrolysis
Journal of Nanoparticle Research, 2003Co-Authors: Camellia Panatarani, Wuled I Lenggoro, Kikuo OkuyamaAbstract:LiNO3 was used as a shield in the preparation of single crystalline ZnO particles by a Spray Pyrolysis process in order to prevent agglomeration and enhance the crystallinity of the ZnO. LiNO3 was added to a precursor solution of zinc acetate dihydrate prior to its atomization by means of an ultrasonic transducer. Agglomerate-free particles having a mean particle size of 26 nm were successfully obtained after washing the product. X-ray diffractometry, field-emission scanning electron micrograph and transmission electron micrograph data indicate that the size and morphology of ZnO were strongly influenced by the operating temperature used and the residence time of the particle in the reactor.
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synthesis of lapo4 ce tb phosphor particles by Spray Pyrolysis
Materials Letters, 2001Co-Authors: Wuled I Lenggoro, Kikuo Okuyama, Bin Xia, Hiroaki Mizushima, Naoto KijimaAbstract:Abstract Spray Pyrolysis method was applied to prepare submicron LaPO4:Ce,Tb phosphor particles. The product characteristics such as photoluminescence, crystallinity, and particle morphology were investigated under various preparation conditions and compared with those of commercial ones. The prepared powders showed 543-nm green emission characteristics. The maximum photoluminescence intensity was obtained at 1550°C.
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yag ce phosphor particles prepared by ultrasonic Spray Pyrolysis
Materials Research Bulletin, 2000Co-Authors: Yun Chan Kang, Wuled I Lenggoro, Seung Bin Park, Kikuo OkuyamaAbstract:Abstract Spray Pyrolysis was applied to the preparation of fine YAG:Ce phosphor particles. The characteristics of particles such as crystallinity, morphology, and photoluminescence were investigated. Phase-pure YAG:Ce particles with high crystallinity were obtained after annealing at lower temperatures than those of conventional preparation processes. The mean size of the particles increased from 0.46 to 1.2 μm when the overall solution concentrations were changed from 0.03 to 1 mol/L. The YAG:Ce particles annealed at 1300°C were nonaggregated and spherical. The particles absorbed excitation energy in the range 403–510 nm, and the maximum excitation wavelength was near 470 nm. The YAG:Ce particles showed broad emission peaks in the range 480–650 nm and had maximum intensity at 528 nm. The photoluminescence intensity of the particles increased monotonically with increasing annealing temperature and showed the maximum value at 1 at% Ce.
Sotiris E Pratsinis - One of the best experts on this subject based on the ideXlab platform.
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Uniform nanoparticles by flame-assisted Spray Pyrolysis (FASP) of low cost precursors
Journal of Nanoparticle Research, 2011Co-Authors: Thomas Rudin, Karsten Wegner, Sotiris E PratsinisAbstract:A new flame-assisted Spray Pyrolysis (FASP) reactor design is presented, which allows the use of inexpensive precursors and solvents (e.g., ethanol) for synthesis of nanoparticles (10–20 nm) with uniform characteristics. In this reactor design, a gas-assisted atomizer generates the precursor solution Spray that is mixed and combusted with externally fed inexpensive fuel gases (acetylene or methane) at a defined height above the atomizing nozzle. The gaseous fuel feed can be varied to control the combustion enthalpy content of the flame and onset of particle formation. This way, the enthalpy density of the flame is decoupled from the precursor solution composition. Low enthalpy content precursor solutions are prone to synthesis of non-uniform particles (e.g., bimodal particle size distribution) by standard flame Spray Pyrolysis (FSP) processes. For example, metal nitrates in ethanol typically produce nanosized particles by gas-to-particle conversion along with larger particles by droplet-to-particle conversion. The present FASP design facilitates the use of such low enthalpy precursor solutions for synthesis of homogeneous nanopowders by increasing the combustion enthalpy density of the flame with low-cost, gaseous fuels. The effect of flame enthalpy density on product properties in the FASP configuration is explored by the example of Bi_2O_3 nanoparticles produced from bismuth nitrate in ethanol. Product powders were characterized by nitrogen adsorption, X-ray diffraction, X-ray disk centrifuge, and transmission electron microscopy. Homogeneous Bi_2O_3 nanopowders were produced both by increasing the gaseous fuel content and, most notably, by cutting the air entrainment prior to ignition of the Spray.
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wafer level flame Spray Pyrolysis deposition of gas sensitive layers on microsensors
Journal of Micromechanics and Microengineering, 2008Co-Authors: S Kuhne, Sotiris E Pratsinis, Antonio Tricoli, Markus Graf, Felix Mayer, Andreas HierlemannAbstract:This paper presents a CMOS-compatible wafer-level fabrication process for monolithic CMOS/MEMS sensor systems coated with sensitive layers directly deposited by means of flame Spray Pyrolysis (FSP). Microhotplate (?HP)-based devices, featuring an FSP directly deposited SnO2/Pt layer, have successfully been realized on a wafer level. The thermal characterization evidenced a thermal resistance of 10.6 ?C mW?1; moreover, gas test measurements with ethanol have been performed. Microhotplate membrane deformations during device operation have been investigated and have been reduced by adjustment of the intrinsic stress of a deposited silicon nitride layer.
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nanorods of zno made by flame Spray Pyrolysis
Chemistry of Materials, 2006Co-Authors: Murray J Heigh, Sotiris E Pratsinis, Lutz Madle, Frank KrumeichAbstract:Inorganic nanorods with closely controlled aspect ratio were made by flame Spray Pyrolysis − a single-step, continuous, and scaleable process. Indium and tin dopants selectively affect a specific ZnO crystal plane and are incorporated into its lattice. Nanorod formation is attributed to the higher valency and coordination of indium and tin dopants relative to zinc and the associated disruption of crystal growth within the Zn plane. In contrast, lithium, with an equivalent ionic radius to these dopants but lower valency than zinc, has no effect on the ZnO texture. The formation of the nanorods within the flame occurs by annealing crystallization during flame cooling.
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morphology and deposition of thin yttria stabilized zirconia films using Spray Pyrolysis
Thin Solid Films, 2005Co-Authors: Dainius Perednis, Sotiris E Pratsinis, O Wilhelm, Ludwig J GaucklerAbstract:A comparison of two Spray Pyrolysis techniques, Electrostatic Spray Deposition (ESD) and Pressurized Spray Deposition (PSD), is presented in this paper. Both techniques have been applied for the deposition of thin yttria-stabilized zirconia (YSZ) films. Thin films with various morphologies have been deposited using the ESD technique. For both techniques, the main parameter that determines the film morphology was the substrate temperature. Using ESD, the surface morphology was strongly influenced by the composition of the precursor solution and deposition time. When the PSD technique was used for film deposition, the influence of these parameters on film morphology was not pronounced.
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bismuth oxide nanoparticles by flame Spray Pyrolysis
Journal of the American Ceramic Society, 2004Co-Authors: Lutz Madle, Sotiris E PratsinisAbstract:Bismuth oxide nanostructured particles were made via the flame Spray Pyrolysis (FSP) of bismuth nitrate that had been dissolved in a solution of ethanol/nitric acid or in acetic acid. These self-sustaining Spray flames produced tetragonal β-Bi 2 O 3 . The use of ethanol/nitric acid solutions resulted in a mixture of hollow, shell-like, and solid nanograined particles. The particle homogeneity was improved as the content of acetic acid in the precursor solution increased. Solid bismuth oxide nanoparticles were prepared consistent with percolation theory, accounting for the specific volume of the product and the precursor. Using pure acetic acid as the solvent, the effect of FSP variables on Spray flame and product powder characteristics was investigated. The specific surface area of the Bi 2 O 3 particles could be controlled over a range of 20-80 m 2 /g by the liquid feed and oxygen gas flow rates for powder production rates of 6-46 g/h.
Seung Bin Park - One of the best experts on this subject based on the ideXlab platform.
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ultrasonic Spray Pyrolysis for air stable copper particles and their conductive films
Acta Materialia, 2021Co-Authors: Dae Soo Jung, Hye Young Koo, Seung Bin Park, Sung Eun Wang, Yun Chan KangAbstract:Abstract Copper (Cu) particles are key components in metal pastes and inks used for conductive electrodes in electronic circuits printed by various methods. However, Cu particles typically suffer from severe oxidation in air, imposing a significant challenge in handling copper particles in manufacturing processes. In this study, ultrasonic Spray Pyrolysis was adopted to generate a large quantity of Cu particles coated with barium borosilicate (BBS) glass to overcome this chronic oxidation issue, as well as to develop stable conductive films. The Spray Pyrolysis process is simple, because the copper and glass materials spontaneously segregate into the core and shell of each particle, respectively, to form core-shell-structured BBS-coated Cu (Cu@BBS) particles. The glass surface layers confer substantial oxidation resistance to the copper particles, as evidenced by analyses after long-term exposure to air. The thin glass layers serve as a sintering promoter and inorganic binder; thus, highly dense conductive copper films with good adhesion to the substrates were formed after sintering. The film obtained from the Cu@BBS particles exhibited resistivities of 2.01 μΩ•cm. The Cu@BBS particles introduced herein are readily applicable in various industrial processes where Spray Pyrolysis has long been established.
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design of particles by Spray Pyrolysis and recent progress in its application
ChemInform, 2012Co-Authors: Dae Soo Jung, Seung Bin Park, Yun Chan KangAbstract:Spray Pyrolysis is a promising aerosol process to produce “designer particles” of precisely controlled morphology with decorations on surfaces or inside particles. Need of precise control of properties has sparked researches on aerosol process that may replace conventional processes such as solid state reaction process or liquid precipitation method. However, productivity is the biggest obstacle in the development of a commercial scale process because the aerosol process is essentially operated at low particle concentration compared to liquid phase processes. In this review, by reviewing publications for the last 10 years we discuss how researchers on Spray Pyrolysis circumvent this inherent limitation of the aerosol process. First, the process of particle design by Spray Pyrolysis is introduced. Some key criteria are explained for selecting each component of Spray Pyrolysis: precursor, additive, carrier gas, heat source, and reactor type. Second, key contributions of major groups in Korea, Japan, Europe, and America are described. Third, some of named processes to overcome productivity of Spray aerosol process are introduced. Fourth, applications of Spray Pyrolysis to materials related to alternative energy, environmental cleaning, information processing and display, and biomaterials are considered. Finally, future prospects of Spray Pyrolysis are discussed along with current standing issues for further progress of Spray Pyrolysis.
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h2 evolution under visible light irradiation from aqueous methanol solution on srtio3 cr ta prepared by Spray Pyrolysis from polymeric precursor
International Journal of Hydrogen Energy, 2011Co-Authors: Hyun Woo Kang, Seung Bin ParkAbstract:Abstract SrTiO 3 :Cr/Ta powders were prepared by Spray Pyrolysis from polymeric precursors. Effects of the amount of co-dopant and additives on the photocatalytic activity for hydrogen evolution from aqueous methanol solution under visible light irradiation ( λ > 415 nm) were investigated. For the photocatalyst prepared by Spray Pyrolysis from polymeric precursor, the hydrogen evolution rate was increased by a factor of ∼100 and induction period was decreased by a factor of 8 compared with a photocatalyst prepared by solid state reaction. These enhancements result from increased roughness of surface, and the compositional uniformity which are intrinsic characteristics of Spray Pyrolysis. In addition, photocatalyst prepared by Spray Pyrolysis from polymeric precursor have large BET surface area and small amount of Cr 6+ ion which is responsible for long induction period. It should be noted that the reduction of Cr 6+ ion was achieved without hydrogen reduction process.
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synthesis and properties of ce1 xgdxo2 x 2 solid solution prepared by flame Spray Pyrolysis
Materials Research Bulletin, 2006Co-Authors: Dae Jong Seo, Seung Bin Park, Kyoung Ok Ryu, Kiyoung Kim, Rakhyun SongAbstract:Flame Spray Pyrolysis, which produces ultrafine particles, was applied to the synthesis of Ce1−xGdxO2−x/2 solid solutions by substituting Gd from a mole fraction of 0–0.40. The solubility limit of Gd in the Ce1−xGdxO2−x/2 solid solution produced by flame Spray Pyrolysis was between 0.25 and 0.30, which is consistent with the reported value. The as-prepared Ce1−xGdxO2−x/2 particles had a square morphology and a nanometer range in the equivalent diameter. The small particle size made it possible to reduce the sintering temperature of the Ce1−xGdxO2−x/2 solid solution from 1650 °C to 1400 °C for the ceria-based solid electrolytes produced by the solid state preparation. The maximum ionic conductivity was achieved when the mole fraction of Gd was 0.25. The mole fraction for the highest ionic conductivity was the same as the particles produced by hydrothermal synthesis. However, the ionic conductivity of the Ce1−xGdxO2−x/2 prepared by the flame Spray Pyrolysis (1.01 × 10−2 S/cm at 600 °C) was higher than that prepared by the hydrothermal synthesis (7.53 × 10−3 S/cm at 600 °C).
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morphological and optical characteristics of y2o3 eu phosphor particles prepared by flame Spray Pyrolysis
Japanese Journal of Applied Physics, 2001Co-Authors: Yun Chan Kang, Dae Jong Seo, Seung Bin Park, Hee Dong ParkAbstract:Y2O3:Eu phosphor particles were prepared by flame Spray Pyrolysis and compared with the particles prepared by general Spray Pyrolysis. The particles prepared by flame Spray Pyrolysis had a spherical and dense morphology and were finer than the particles prepared by general Spray Pyrolysis. Flame temperature was an important factor in the preparation of the phosphor particles by flame Spray Pyrolysis. To obtain Y2O3:Eu particles with a uniformly dense structure, a sufficiently high temperature to form monoclinic phase was required. Too low flame temperature generated nonspherical and hollow particles with cubic phase because the particles did not melt completely, and too high flame temperature of flame generated many nanoparticles due to evaporation. After stepwise post-treatment of as-prepared particles with monoclinic phase and the dense structure, Y2O3:Eu phosphor particles with high brightness and cubic phase were obtained. The Y2O3:Eu phosphor particles prepared by flame Spray Pyrolysis showed 120% photoluminescence intensity in comparison with the particles prepared by general Spray Pyrolysis.
