Design of particles by spray pyrolysis and recent progress in its application

박승빈,정대수,강윤찬 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.6

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.

고온 분무열분해 공정에 의한 녹색 발광의 BAM:Mn 형광체 합성

주서희,구혜영,김도엽,강윤찬,Ju Seo Hee,Koo Hye Young,Kim Do Youp,Kang Yun Chan 한국재료학회 2005 한국재료학회지 Vol.15 No.8

Green-light emitting $BaMgAl_{10}O_{19}:Mn^{2+}$ (BAM:Mn) phosphor particles were prepared by spray Pyrolysis. The effect of reactor temperature and flow rate of carrier gas in the spray Pyrolysis on the morphology, crystallinity and photoluminescence characteristics under vacuum ultraviolet were investigated. The morphology of the as-Prepared Particles obtained by spray Pyrolysis had spherical shape and non-aggregation characteristics regardless of the reactor temperature. The spherical shape of the as-prepared Particles obtained by spray pyrolysis at low temperature disappeared after Post-treatment. On the other hand the as-Prepared Particles obtained by spray Pyrolysis at $1600^{\circ}C$ maintained spherical shape and non-aggregation characteristics after post-treatment at $1400^{\circ}C$ for 3 h under reducing atmosphere. The BAM:Mn Phosphor Particles Prepared by spray Pyrolysis at different reactor temperatures had pure crystal structure and high photoluminescence intensities under vacuum ultraviolet after post-treatment. BAM:Mn phosphor particles prepared by spray Pyrolysis at low How rate of carrier gas had complete spherical shape and filed morphology and high photoluminescence intensity after post-treatment under reducing atmosphere.

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.

분무열분해공정 하에서 합성 조건이 열원 소재로서의 Fe 분말 특성에 미치는 영향

구혜영,김정현,홍승권,한진만,고유나,이수민,고다래,강윤찬,강승호,조성백,Koo, Hye-Young,Kim, Jung-Hyun,Hong, Seung-Kwon,Han, Jin-Man,Ko, You-Na,Lee, Su-Min,Ko, Da-Rae,Kang, Yun-Chan,Kang, Seung-Ho,Cho, Sung-Baek 한국재료학회 2009 한국재료학회지 Vol.19 No.11

Fe powders with elongated and aggregated structure as heat pellet material for thermal battery applications were prepared by spray pyrolysis under various preparation conditions. The precursor powders with spherical shapes and hollow morphologies turned into Fe powders after reduction at a temperature of 615$^{\circ}C$ under 20% $H_2$/Ar gas. The powders had pure Fe crystal structures irrespective of the preparation conditions of the precursor powders in the spray pyrolysis. The morphologies and mean sizes of the Fe powders are affected by the preparation conditions of the precursor powders in the spray pyrolysis. Therefore, the ignition sensitivities and the burn rates of the heat pellets formed from the Fe powders prepared by spray pyrolysis are affected by the preparations of the precursor powders. The Fe powders prepared under the optimum preparation conditions have a BET surface area of 2.9 $m^2g^1$. The heat pellets prepared from the Fe powders with elongated and aggregated structure have a good ignition sensitivity of 1.1W and a high burn rate of 18 $cms^1$.

초음파 분무 열분해와 가압소결로 제조한 이트리아 분산입자 강화 텅스텐의 특성

이의선,허연지,김지영,이영인,석명진,오승탁 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.3

The effects of fabrication method on the microstructure and sinterability of W-1 wt% Y2O3 wereanalyzed. W composite powders dispersed with Y2O3 particles were synthesized by the ultrasonic spraypyrolysis process or the ultrasonic spray pyrolysis/polymer solution process. A dense composite was fabricatedby a combination of spark plasma sintering and final hot isostatic pressing. The powder synthesized by theultrasonic spray pyrolysis had fine dispersed particles on the surface of the cubic powder and was composedof W, Y2O3 and W-oxides. On the other hand, in the case of the ultrasonic spray pyrolysis/polymer solutionprocess, the nano-sized particles formed agglomerates and existed only as pure W and Y2O3 phases. All thesintered compacts treated with HIP showed an increase in relative density, and the sintered compacts of thepowder synthesized by the ultrasonic spray pyrolysis/polymer solution process showed a maximum relativedensity of 97~99% and a fine grain size. The change in microstructure with different powder processing wasexplained by the presence of W-oxide and the size and distribution of Y2O3 particles. The Vickers hardnessof the sintered compact reached the largest value of about 5 GPa in the powder synthesized by the ultrasonicspray pyrolysis/polymer solution process, which was interpreted to be a result of the relatively high densityand decreased grain size.

H₂ evolution under visible light irradiation from aqueous methanol solution on SrTiO₃:Cr/Ta prepared by spray pyrolysis from polymeric precursor

Kang, H.W.,Park, S.B. Pergamon Press ; Elsevier Science Ltd 2011 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.36 No.16

SrTiO<SUB>3</SUB>: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<SUP>6+</SUP> ion which is responsible for long induction period. It should be noted that the reduction of Cr<SUP>6+</SUP> ion was achieved without hydrogen reduction process.

Excellent Li-ion storage performances of hierarchical SnO-SnO₂ composite powders and SnO nanoplates prepared by one-pot spray pyrolysis

Kim, Jung Hyun,Jeon, Kyung Min,Park, Jin-Sung,Kang, Yun Chan Elsevier 2017 Journal of Power Sources Vol.359 No.-

<P><B>Abstract</B></P> <P>Hierarchical-structured SnO-SnO<SUB>2</SUB> composite powders and SnO nanoplates with some SnO<SUB>2</SUB> nanorods are prepared by one-pot spray pyrolysis. Dicyandiamide dissolved in the spray solution plays a key role in the preparation of the hierarchical-structured SnO-SnO<SUB>2</SUB> composite powder and SnO nanoplates. The hierarchical-structured SnO-SnO<SUB>2</SUB> composite powders, in which the SnO nanoplates are trapped in the porous SnO<SUB>2</SUB> nanosphere, are prepared by spray pyrolysis at 800 °C. Sufficient conversion of the porous SnO<SUB>2</SUB> nanospheres to SnO at 900 °C results in aggregation-free SnO<SUB>2</SUB> nanoplates. SnO<SUB>2</SUB> nanorods with a spherical nanodroplet at the tip are formed by Ostwald ripening. The hierarchical-structured SnO-SnO<SUB>2</SUB> composite powder having high structural stability during repeated lithium alloying and dealloying reactions, shows superior discharge capacities and rate performances for lithium-ion storage compared to those of the dense-structured SnO<SUB>2</SUB> powders. The discharge capacities of the hierarchical-structured SnO-SnO<SUB>2</SUB> composite powders, SnO nanoplates with SnO<SUB>2</SUB> nanorods, and dense-structured SnO<SUB>2</SUB> powders at a current density of 1 A g<SUP>−1</SUP> for the 300th cycle are 561, 504, and 416 mA h g<SUP>−1</SUP>, respectively. The SnO nanoplates with SnO<SUB>2</SUB> nanorods and hierarchical-structured SnO-SnO<SUB>2</SUB> powders deliver high reversible discharge capacities of 433 and 379 mA h g<SUP>−1</SUP> at an extremely high current density of 10 A g<SUP>−1</SUP>, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hierarchical-structured SnO-SnO<SUB>2</SUB> composite are prepared by one-pot spray pyrolysis. </LI> <LI> SnO nanoplates with some SnO<SUB>2</SUB> nanorods are prepared by one-pot spray pyrolysis. </LI> <LI> SnO-SnO<SUB>2</SUB> and SnO nanoplates show excellent lithium-ion storage performances. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Spray Pyrolysis에 의한 Manganese Oxide 입자의 제조 및 전기화학적 특성

최원창,변동진,이중기,박달근,김현중,Choi, Won-Chang,Byun, Dong-Jin,Lee, Jung-Kee,Park, Dal-Keun,Kim, Hyeon-Joong 한국재료학회 2001 한국재료학회지 Vol.11 No.11

Spray pyrolysis is a favorable technique to form complex mixed-metal oxide powders with high purity in high temperature region. Manganese oxide powders were prepared by spray pyrolysis from an aqueous solution of $Mn(NO_3)_2$. Powders were formed in the temperature range of 500~$700^{\circ}C$ under the constant pressure of 300torr. All the powders have hydrous forms. When the temperature was increased, the size and the surface area of the particles decreased. An electrochemical capacitors were made with manganese oxide electrodes and KOH electrolyte. With the temperature decreased, capacitors showed high capacitance. Capacitor which was prepared with powders formed in the temperature $500^{\circ}C$ demonstrated specific capacitances as high as 83F/g.

스프레이 공정을 이용한 nc-ZnO/ZnO 전계효과트랜지스터의 광학적 노출에 대한 열화 현상 분석

조준희 한국반도체디스플레이기술학회 2023 반도체디스플레이기술학회지 Vol.22 No.1

Metal oxide semiconductor (MOS) adapting spray-pyrolysis deposition technique has drawn large attention based on their high quality of intrinsic and electrical properties in addition to simple and low-cost processibility. To fully utilize the merits of MOS field-effect transistors (FETs) , transparency, it is important to understand the instability behaviors of FETs under illumination. Here, we studied the photo-induced properties of nc-ZnO/ZnO field-effect transistors (FETs) based on spray-pyrolysis under illumination which incorporating ZnO nanocrystalline nanoparticles into typical ZnO precursor. Our experiments reveal that nc-ZnO in active layer suppressed the light instabilities of FETs.

Characteristics of nano-sized La0.75Sr0.25Cr0.5Mn0.5O3 powders prepared by spray pyrolysis

정대수,강윤찬,Hee Chan Jang,Jung Hyun Kim,Hye Young Koo,Yoon Ho Cho,이종흔 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3

Nano-sized La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) powders were prepared by calcination of precursor powders obtained by spray pyrolysis. The precursor powders prepared from the spray solutions with citric acid or ethylene glycol had a spherical shape and a hollow morphology. The precursor powders were converted to nano-sized LSCM powders after calcination at high temperatures. The mean sizes of the LSCM powders calcined at temperatures of 700 and 800 oC were 70 and 90 nm. However,the mean sizes of the LSCM powders calcined at temperatures of 1000 and 1100 oC were 0.38 and 0.78 μm. The sintered pellets formed from the LSCM powders obtained from the spray solution without an organic additive had high porosities. The hollow structure of the LSCM powders produced the sintered pellets with high porosities. The sintered pellets obtained from the nanosized LSCM powders had dense structures and low porosities. However, the sintered pellets obtained from the submicrometresized LSCM powders had regular pore structures and high porosities.