액적 분급 장치를 적용한 분무열분해 공정으로부터 합성된 실리카 분말의 특성

강윤찬,주서희,구혜영,강희상,박승빈,Kang, Yun-Chan,Ju, Seo-Hee,Koo, Hye-Young,Kang, Hee-Sang,Park, Seung-Bin 한국재료학회 2006 한국재료학회지 Vol.16 No.10

Silica powders with spherical shape and narrow size distribution were prepared by large-scale ultrasonic spray pyrolysis applying the droplet classification apparatus. On the other hand, silica powders prepared by large-scale ultrasonic spray pyrolysis without droplet classification apparatus had broad size distribution. Droplet classification apparatus used in this paper applied the principles of cyclone and dispersion plate with small holes. The droplets formed from the ultrasonic spray generator applying the droplet classification apparatus had narrow size distribution. The droplets with fine and large sizes were eliminated by droplet classification apparatus. The optimum flow rate of the carrier gas and diameter of the hole of the dispersion plate were studied to reduce the size distribution of the silica powders prepared by large-scale ultrasonic spray pyrolysis. The size distribution of the silica powders prepared by large-scale ultrasonic spray pyrolysis at the optimum preparation conditions was 0.76.

Terbium-doped lanthanum phosphate phosphor particles with a submicrometre size and spherical shape

강윤찬,Jin Man Han,Hye Young Koo,Jung Sang Cho,정대수 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5

Submicrometre-sized LaPO4:Tb phosphor particles with a spherical shape and filled morphology were prepared by spray pyrolysis from a polymeric precursor solution containing citric acid and ethylene glycol. The LaPO4:Tb phosphor particles obtained from the aqueous spray solution had a hollow morphology and large size because of the high drying and decomposition rates of droplets. The mean sizes of the particles obtained from the aqueous spray and polymeric precursor solutions were each 1 and 0.8 μm, respectively. The optimum post-treatment temperature for the preparation of LaPO4:Tb phosphor particles with a spherical shape and high brightness was 1100oC. The prepared LaPO4:Tb phosphor particles had high photoluminescence intensities under vacuum ultraviolet illumination of 147 nm.

연소합성법에 의한 기능성 세라믹 소재 합성

강윤찬,정경열,박승빈 한국연소학회 2003 KOSCOSYMPOSIUM논문집 Vol.- No.-

Effects of NH4Cl flux on the characteristics of yttrium oxide phosphor particles with a spherical shape

강윤찬,Hye Young Koo,Seung Kwon Hong 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.4

High brightness Y2O3:Eu phosphor particles with a spherical shape and fine size were prepared by spray pyrolysis from spray solutions with polymeric precursors, a drying control chemical additive and ammonium chloride flux. The phosphor particles prepared from the spray solution with the ammonium chloride flux had a hollow and porous structure after post-treatment. However, the phosphor particles prepared from the spray solution with polymeric precursors, a drying control chemical additive and ammonium chloride flux had a spherical shape and filled inner structure after post-treatment. The optimum content of the NH4Cl flux showing the maximum photoluminescence intensity of the Y2O3:Eu phosphor particles was 6 wt%. The improvement of the photoluminescence intensity of the Y2O3:Eu phosphor particles by additions of ammonium chloride flux, polymeric precursors and a drying control chemical additive into the spray solution was 37%. High brightness Y2O3:Eu phosphor particles with a spherical shape and fine size were prepared by spray pyrolysis from spray solutions with polymeric precursors, a drying control chemical additive and ammonium chloride flux. The phosphor particles prepared from the spray solution with the ammonium chloride flux had a hollow and porous structure after post-treatment. However, the phosphor particles prepared from the spray solution with polymeric precursors, a drying control chemical additive and ammonium chloride flux had a spherical shape and filled inner structure after post-treatment. The optimum content of the NH4Cl flux showing the maximum photoluminescence intensity of the Y2O3:Eu phosphor particles was 6 wt%. The improvement of the photoluminescence intensity of the Y2O3:Eu phosphor particles by additions of ammonium chloride flux, polymeric precursors and a drying control chemical additive into the spray solution was 37%.

The effect of manganese oxide precursors on the characteristics of LiMn2O4 cathode particles

강윤찬,Seo Hee Ju,Hee Chan Jang,Man-Jong Lee 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.2

Manganese oxide particles with nanometre and several micrometre sizes were prepared by spray pyrolysis from aqueous and polymeric spray solutions. The LiMn2O4 particles prepared from Mn2O3 particles obtained from an aqueous solution with a manganese nitrate precursor had micrometre sizes and a spherical shape. On the other hand, the LiMn2O4 particles prepared from nano-sized Mn2O3 particles obtained from polymeric spray solutions had a fine size, a narrow size distribution, and regular morphology irrespective of the type of manganese precursors. The discharge capacities of the LiMn2O4 particles obtained from an aqueous spray solution with a manganese nitrate precursor dropped from 136 to 115 mAh/g by the 25 th cycle at a current density of 0.1 C. On the other hand, the discharge capacities of the LiMn2O4 particles obtained from a polymeric spray solution with a manganese nitrate precursor dropped from 121 to 105 mAh/g.

The properties of Li-Ni-Mn-O powders prepared by spray pyrolysis

강윤찬,Eun Byul Jo,주서희,Hee Chan Jang 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5

Li-Ni-Mn-O cathode powders with various ratios of nickel and manganese components were prepared by ultrasonic spray pyrolysis from polymeric precursor solutions. The precursor powders obtained from the polymeric precursor solutions containing citric acid and ethylene glycol were several micrometre in size, had a spherical shape and hollow morphology irrespective of the ratios of nickel and manganese components. However, the morphology of the post-treated Li-Ni-Mn-O cathode powders were affected by the ratios of nickel and manganese components. The LiMn1.5Ni0.5O4 and LiNi0.5Mn0.5O2 cathode powders were several micrometre in size, had a hollow and spherical morphology. However, the LiMn2O4 and LiNi0.75Mn0.25O2 cathode powders had a fine size and regular morphology. The mean sizes of the LiMn2O4 and LiNi0.75Mn0.25O2 cathode powders were 1.2 and 0.26 μm, respectively. The initial discharge capacities of the prepared Li-Ni-Mn-O cathode powders were changed from 120 to 206 mAhg−1 according to the ratios of nickel and manganese components. Li-Ni-Mn-O cathode powders with various ratios of nickel and manganese components were prepared by ultrasonic spray pyrolysis from polymeric precursor solutions. The precursor powders obtained from the polymeric precursor solutions containing citric acid and ethylene glycol were several micrometre in size, had a spherical shape and hollow morphology irrespective of the ratios of nickel and manganese components. However, the morphology of the post-treated Li-Ni-Mn-O cathode powders were affected by the ratios of nickel and manganese components. The LiMn1.5Ni0.5O4 and LiNi0.5Mn0.5O2 cathode powders were several micrometre in size, had a hollow and spherical morphology. However, the LiMn2O4 and LiNi0.75Mn0.25O2 cathode powders had a fine size and regular morphology. The mean sizes of the LiMn2O4 and LiNi0.75Mn0.25O2 cathode powders were 1.2 and 0.26 μm, respectively. The initial discharge capacities of the prepared Li-Ni-Mn-O cathode powders were changed from 120 to 206 mAhg−1 according to the ratios of nickel and manganese components.

Fine-sized Bi0.5Na0.5TiO3 powders prepared by spray pyrolysis from polymeric precursors

강윤찬,정대수,Hye Young Koo 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.4

Bi0.5Na0.5TiO3 (BNT) powders with nanometre and micrometre sizes were prepared by an ultrasonic spray pyrolysis process. The BNT powders obtained from the spray solution without citric acid had a spherical shape and micrometre size. On the other hand, the BNT powders obtained from a spray solution with 0.4M citric acid of had nanometre size at a calcination temperature of 700 oC. Single phase BNT powders with a rhombohedral structure were obtained at a calcination temperature of 700 oC. The sintering of pellets obtained from the micrometre sized BNT powders started at a temperature of 900 oC. On the other hand, sintering and grain growth of the pellet obtained from the nanometre sized BNT powders occurred even at the low temperature of 850 oC. The relative densities of the pellets obtained from the nanometre sized BNT powders were 95and 96% of the theoretical density of BNT at sintering temperatures of 950 and 1000 oC. The mean grain sizes of the pellets sintered at temperatures of 950 and 1000 oC were the same at 1.10 μm.

Preparation of Pb-based glass powders by spray pyrolysis using a filter expansion aerosol generator

강윤찬,Seung Kwon Hong,Hye Young Koo,정대수,Jung Sang Cho 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.4

PbO-B2O3-SiO2 glass powders were directly prepared by a filter expansion aerosol generator (FEAG) process. Glass powders were formed by melting and cooling processes of the powders inside the hot wall reactor which was maintained at a low pressure. The powders prepared at temperatures below 800oC had a spherical shape and submicrometre size. One glass powder was formed from one droplet at preparation temperatures below 800oC. On the other hand, the powders prepared at a temperature of 900oC had a bimodal size distribution with nanometre and submicrometre size. The mean size of the glass powders prepared by the FEAG process at a temperature of 800oC was 320 nm. In the DSC curve, the glass transition temperature (Tg) of the glass powders was 411.5oC. The transparencies of the dielectric layers formed from the glass powders obtained by the FEAG process were higher than 90% within the visible light range at annealing temperatures above 500oC.

나노 형광체 합성 기술

강윤찬 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.2

화염분무열분해 공정에 의해 합성되어진 Zn₂SiO₄:Mn 형광체

강윤찬,손종락,정경열,Kang Y. C.,Sohn J. R.,Jung K. Y. 한국재료학회 2004 한국재료학회지 Vol.14 No.8

$Zn_{2}SiO_{4}:Mn$ phosphor particles were prepared by a flame spray pyrolysis method. It has been generally known that the high-temperature flame enables fast drying and decomposition of droplets. In the present investigation, the morphology and luminescent property of $Zn_{2}SiO_{4}:Mn$ phosphor were controlled in a severe flame preparation condition. The particle formation in the flame spray pyrolysis process was achieved by the droplet-to-particle conversion without any evaporation of precursors, which made it possible to obtain spherical $Zn_{2}SiO_{4}:Mn$ particles of a pure phase from a droplet. Using colloidal solutions wherein dispersed nano-sized silica particles were adopted as a silicon precursor. $Zn_{2}SiO_{4}:Mn$ particles with spherical shape and filled morphology were prepared and the spherical morphology was maintained even after the high-temperature heat treatment, which is necessary to increase the photoluminescence intensity. The $Zn_{2}SiO_{4}:Mn$ particles with spherical shape, which were prepared by the flame spray pyrolysis and posttreated at $1150^{\circ}C$, showed good luminescent characteristics under vacuum ultraviolet (VUV) excitation.