• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.12-18
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• 2019

The spherical $SiO_2$ powders were synthesized by the scaled-up ultrasonic pyrolysis (USP). The aqueous $SiO_2$ sol, which contained 20~30 nm $SiO_2$ particles, was used as a precursor for the scaled-up USP. The effects of the USP operating conditions and precursor conditions were systematically investigated, including reaction temperature, gas flow rate, and the concentration of $SiO_2$ sol on the morphologies of synthesized $SiO_2$ particles. the synthesized $SiO_2$ particle showed a pseudo-crystal phase, spherical morphology, and a smooth surface. The size of the spherical $SiO_2$ particle decreased as both reaction temperature increased and precursor concentration decreased. In addition, the synthesized $SiO_2$ particle size was increased by increasing the gas flow rate. Lastly, the scaled-up USP was compared with the lab-scale USP based on the same process conditions. Due to a short retention time in the reaction tube during the USP process, the $SiO_2$ particle synthesized via the lab-scale USP showed a larger particle size.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.281-284
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• 2004

본 연구에서는 분무열분해 공정에 의해 폐산용액으로부터 평균입도 100nm 이하의 나노 분말을 제조하였다. 용액 내의 Fe 성분의 농도가 20 g/$\iota$로부터 200 g/$\iota$로 증가됨에 따라 생성된 분말의 입도는 30 nm로부터 60 nm 까지 점점 증가하는 반면 입도분포는 더욱 불규칙하게 나타나고 있었다. 또한 용액 내의 농도 증가에 따라 $NiFe_2O_4$ 상의 생성비율이 현저히 증가하고 있었으며, 입자들의 비표면적은 현저히 감소하였다. 공기압력이 $1 kg/cm^2$까지는 분말의 평균입도는 80$\~$100 nm로 공기압력의 증가에 따라 분말들의 평균입도는 현저한 변화를 나타내지 않았으며, 생성된 상들의 비율의 현저한 변화도 나타나지 않았다. 공기압력이 $3kg/cm^2$로 증가하는 경우에는 평균입도가 약 70 nm로 감소하였으며 $NiFe_2O_4$의 생성비율도 감소하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.99-99
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• 2003

최근들어 차세대 디스플레이 시장이 뜨겁게 달아오르고있다. 이에 따라서 보다 나은 발광특성 및 긴수명, 적정 잔광시간등 보다 우수한 형광체개발이 더욱 절실한 시점이다. 본 연구에서는 많은 형광체 후보물질중 하나인 yttrium silicate를 기상법으로 제조하였는데, 질산염 형태인 yttrium과 Tb에 소량의 질산에 용해시킨 Tetraethyl orthosilicate를 혼합하여 분무용액을 만든다음 분무 열분해법으로 제조하여 나온 $Y_2$SiO$_{5}$:Tb 입자들의 형상 및 발광특성등을 살펴보았다.

• Resources Recycling
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• v.27 no.2
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• pp.24-31
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• 2018

In this study, waste ITO target is dissolved into hydrochloric acid to generate a complex indium-tin chloride solution. Nano sized ITO powder with an average particle size below 30 nm are generated from these raw material solutions by spray pyrolysis process. Also, in this study, thermodynamic equations for the formation of indium-tin oxide (ITO) are established. As the reaction temperature increased from $800^{\circ}C$ to $900^{\circ}C$, the proportion and size of the spherical droplet shape in which nano sized particles aggregated gradually decreased, and the surface structure gradually became densified. When the reaction temperature was $800^{\circ}C$, the average particle size of the generated powder was about 20 nm, and no significant sintering was observed. At a reaction temperature of $900^{\circ}C$, the split of the droplet was more severe than at $800^{\circ}C$, and the rate of maintenance of the initial atomized droplet shape decreased sharply. The average particle size of the powder formed was about 25 nm. The ITO particles were composed of single solid crystals, regardless of reaction temperature. XRD analysis showed that only the ITO phase was formed. Remarkably, the specific surface area decreased by about 30% as the reaction temperature increased from $800^{\circ}C$ to $900^{\circ}C$.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.609-613
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• 2006

Ba2-xSrxSiO4:Eu2+ phosphor particles with the high photoluminescence (PL) intensity under long wavelength ultraviolet (UV) were prepared by spray pyrolysis. The photoluminescence, morphological and crystalline characteristics of $Ba_{2-x.}Sr_{x.}SiO_4:Eu^{2+}$ phosphor particles prepared by spray pyrolysis were investigated. $Ba_{2-x.}Sr_{x.}SiO_4:Eu^{2+}$ phosphor particles prepared by spray pyrolysis had various colors from bluish green to yellow by changing the ratio of barium and strontium of the host material. In case of x=0, the main emission peak of $Ba_2SiO_4:Eu^{2+}$ phosphor was 500 nm. In case of x=2, the main emission peak of $Sr_2SiO_4:Eu^{2+}$ phosphor was 554nm. $Ba_{2-x.}Sr_{x.}SiO_4:Eu^{2+}$ phosphor particles obtained by spray pyrolysis had spherical shape and hollow structure. On the other hand, the post-treated $Ba_{2-x.}Sr_{x.}SiO_4:Eu^{2+}$ phosphor particles had large size and irregular shape. The $Ba_{1.488}Sr_{0.5}SiO_4:Eu_{0.012}{^{2+}}$ phosphor particles had the maximum PL intensity after post-treatment at temperature of $1300^{\circ}C$ for 3h under reduction atmosphere.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.214-219
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• 1998

The transparent conducting tin oxide films were deposited on g1ass substrates by the ultrasonic spray pyrolysis. Examined were effects of deposition parameters on the electrical resistance, optical transmittance, crystal structure, and thickness of tin oxide films. As both the deposition time and concentration of tin(IV) chloride increase, the deposited tin oxide films exhibited the decrease of electrical resistance and optical transmittance in the visible and near infrared region. With increasing heat-treatment temperature in air, the deposited tin oxide films showed the enhanced electrical resistance and optical transmittance. This study suggests that the ultrasonic spray pyrolysis may be a promising deposition technique effectively to prepare transparent conducting films of good quality in a single step.

• Resources Recycling
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• v.27 no.2
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• pp.32-37
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• 2018

This study was conducted as a preliminary study for the recycling of palladium and palladium oxide. In this study, thermodynamic equations for the formation of palladium oxide (PdO) are established. Palladium chloride is dissolved into hydrochloric acid to generate a palladium chloride solution. Nanosized palladium oxide powder with an average particle size below 30 nm were generated from this raw material solution by means of a spray pyrolysis process. The palladium oxide particles were composed of a single solid crystal. The results of XRD analysis showed that only a PdO phase of the generated powder was formed. And, the specific surface area of the generated palladium powder was approximately $32m^2/g$.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.80-84
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• 2005

Nano-sized $Y_2O_3:Eu$ phosphor particles were prepared by ultrasonic spray pyrolysis. The effect of polymeric precursor and lithium carbonate flux on the morphology and luminescence characteristics of nano-sized $Y_2O_3:Eu$ phosphor particles was investigated. When using the spray solution containing both the polymeric precursor and the flux, the $Y_2O_3:Eu$ particles with spherical shape and micron size were turned into nano-sized $Y_2O_3:Eu$ phosphor particles during the post-treatment at high temperature. The mean size of $Y_2O_3:Eu$ phosphor particles was affected by the contents of polymeric precursors and lithium carbonate flux, and preparation temperature. The as-prepared particles by spray pyrolysis at high temperature from solution containing high contents of polymeric precursors had good photoluminescence intensity under vacuum ultraviolet after post-treatment above $1,000^{\circ}C$. The prepared nano-sized $Y_2O_3:Eu$ phosphor particles had comparable photoluminescence intensity under vacuum ultraviolet light with that of the commercial $Y_2O_3:Eu$ phosphor particles prepared by solid state reaction method.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.114-115
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• 2002

다성분계 세라믹스에 대하여 초미립 및 나노 분말을 제조하기 위해 공침법, 비정질 citrate법, 무기 금속염을 이용한 sol-gel법, 분무 열분해법 등과 같이 비교적 단순한 공정이면서 입도 분포가 좁고 재현성이 우수한 구형의 초미립 또는 나노 분말의 제조에 적합한 방법들이 많이 연구되고있다[1-3]. 분무 열분해법은 출발물질로 용액을 사용하고 미세한 액적(droplet)을 초음파 분무 후 열분해 하여 분말을 합성하는 방법으로, 입자의 조성이 균질하고 구형의 형상을 갖는 우수한 결정상을 얻을 수 있다. (중략)

• Resources Recycling
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• v.17 no.6
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• pp.79-88
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• 2008

This study is the previous stage for the mass production technology development of the nano-sized tin oxide powder by the recycling of the wasted tin metal, and nano-sized tin oxide powder with the average particle size below 50 nm is prepared from the tin chloride solution by the spray pyrolysis process. As the reaction temperature increases from 800 to 850, the average particle size of the generated powder increases from 20 to 30 nm. As the reaction temperature increases to 900, the droplet type is composed of the particles with the average size of the 30 nm. while the average size of the independent particles increases up to $80{\sim}100$ nm and the surface microstructure becomes more solid. Until $900^{\circ}C$, as the reaction temperature increases, the XRD peak intensity increases, while the specific surface area decreases. When the reaction temperature increases to 950, most of the powder appears with the independent type and the average particle size decrease down to 70 nm. The XRD peak intensity greatly decreases and the specific surface area increases almost twice.