• Title, Summary, Keyword: Spray pyrolysis

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Preparation of Green-Light Emitting BAM:Mn Phosphor Particles by High Temperature Spray Pyrolysis (고온 분무열분해 공정에 의한 녹색 발광의 BAM:Mn 형광체 합성)

  • Ju Seo Hee;Koo Hye Young;Kim Do Youp;Kang Yun Chan
    • Korean Journal of Materials Research
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    • v.15 no.8
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    • pp.496-502
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    • 2005
  • 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.

Morphology and Photoluminescence Characteristics of Halophosphate Phosphor Particles by Spray Pyrolysis and Flame Spray Pyrolysis

  • Sohn, Jong-Rak;Kang, Yun-Chan;Park, Hee-Dong;Yoon, Soon-Gil
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.803-806
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    • 2002
  • Flame spray pyrolysis was applied to improve the photoluminescence characteristics of blue-emitting $Sr_5(PO_4)_3Cl:Eu^{2+}$ phosphor particles with high brightness for the application to LED phosphor. $Sr_5(PO_4)_3Cl:Eu^{2+}$ prepared from conventional spray pyrolysis had poor PL intensity than that of commercial products under long-wavelength ultraviolet(UV). $Sr_5(PO_4)_3Cl:Eu^{2+}$ phosphor particles prepared by flame spray pyrolysis had PL intensity as same as that of commercial products under long-wavelength UV. Hollow morphology and porous structure of the particles prepared by the flame spray pyrolysis disappeared after posttreatment. Even though the $Sr_5(PO_4)_3Cl:Eu^{2+}$ phosphor particles prepared by the flame spray pyrolysis had irregular shape, the particles had dense structure and clear surface property.

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The Characteristics of Silica Powders Prepared by Spray Pyrolysis Applying Droplet Classification Apparatus (액적 분급 장치를 적용한 분무열분해 공정으로부터 합성된 실리카 분말의 특성)

  • Kang, Yun-Chan;Ju, Seo-Hee;Koo, Hye-Young;Kang, Hee-Sang;Park, Seung-Bin
    • Korean Journal of Materials Research
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    • v.16 no.10
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    • pp.633-638
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    • 2006
  • 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.

The Characteristics of Nano-sized Cobalt Oxide Particles Prepared by Low Pressure Spray Pyrolysis (저압 분무열분해법에 의해 합성된 나노 크기의 코발트 산화물 입자의 특성)

  • Ju, Seo-Hee;Kim, Do-Youp;Kang, Yun-Chan
    • Korean Journal of Materials Research
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    • v.16 no.9
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    • pp.538-542
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    • 2006
  • Nano-sized cobalt oxide powders were prepared by low pressure spray pyrolysis process. The precursor powders obtained by low pressure spray pyrolysis process from the spray solution with ethylene glycol had several microns size and hollow structure. The precursor powders obtained from the spray solution with optimum concentration of ethylene glycol formed the nano-sized cobalt oxide powders with regular morphology after post-treatment without milling process. On the other hand, the cobalt oxide powders obtained from the spray solution without ethylene glycol had submicron size and spherical shape before and after posttreatment. The mean size of the cobalt oxide powders formed from the spray solution with concentration of ethylene glycol of 0.7M was 180 nm after post-treatment at temperature of $800^{\circ}C$. The mean size of the powders could be controlled from several tens nanometer to micron sizes by changing the post-treatment temperatures in the preparation of cobalt oxide powders by low pressure spray pyrolysis process.

Fabrication of fine BSCCO-2223 precursor powder by spray pyrolysis process (분무 열분해방법에 의한 미세 BSCCO-2223 전구분말의 제조)

  • 김성환;유재무;고재웅;김영국;박기호
    • Progress in Superconductivity
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    • v.5 no.1
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    • pp.65-69
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    • 2003
  • Many researches on fabrication process for BSCCO precursor powders have been developed for high J$_{c}$ BSCCO-2223 tape. Spray pyrolysis method for fabrication of precursor powder has many advantages, such as high purity, fine particle size and low carbon content of BSCCO precursor powder. Fine, spherical powders were prepared by ultrasonic spray pyrolysis from the aqueous solution of metal nitrates. BSCCO precursor powders were synthesized with various solutes concentration and heat treatment conditions. Average particle size for spray pyrolysis powders was $1.5∼3\mu\textrm{m}$. Bi-2223/Ag tape was prepared by PIT method and followed by various sintering conditions. BSCCO precursor powders were characterized by XRD, SEM, EDS, Carbon content and particle size analysis.s.

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Spray pyrolysis synthesis of mesoporous TiO2 microspheres and their post modification for improved photocatalytic activity

  • Choi, Jaehyung;Yoo, Kye Sang;Kim, Jinsoo
    • Korean Journal of Chemical Engineering
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    • v.35 no.12
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    • pp.2480-2486
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    • 2018
  • Mesoporous $TiO_2$ microspheres were prepared by spray pyrolysis for photocatalysis. Post modification of $TiO_2$ by heat treatment was performed to optimize its photocatalytic performance. First, spherical $TiO_2$ particles with mesoporous structure were synthesized at pyrolysis temperatures of 500, 600, and $700^{\circ}C$. After characterization by XRD, SEM, and $N_2$ adsorption, a sample prepared at $500^{\circ}C$ was found to possess desirable properties for photocatalytic performance through post-modification. In methylene blue degradation, mesoporous $TiO_2$ microspheres synthesized at $500^{\circ}C$ outperformed other microspheres. Furthermore, samples obtained by spray pyrolysis at $500^{\circ}C$ were calcined at various temperatures as a post-modification process. The sample calcined at $350^{\circ}C$ showed improved photocatalytic activity due to optimal anatase crystallinity and surface area.

Preparation of Fluorescence Particles by Spray Pyrolysis (분무열분해법에의한 형광체 입자의 제조)

  • Kang, Yun-Chan;Jung, Kyeong-Youl;Park, Seung-Bin
    • Korean Chemical Engineering Research
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    • v.44 no.3
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    • pp.235-242
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    • 2006
  • Spray pyrosysis is a process to prepare particles and films by evaporating and decomposing droplets of precursor solutions in the order of 1-10 micrometer in diameter. Key elements of the spray pyrolysis process include precursor, solvent, droplet generator, and reactor. Various combination of these 4 elements produces wide range of particles and films. In general. the current status of the spray pyrolysis technology is not quite promising for commercial success. However, this process will be feasible to produce multicomponent functional materials of controlled morphology. In this paper, current status of the spray pyrolysis technology is introduced with the emphasis of production of fluorescence particles.

Photoluminescence Characteristics of Eu-doped YBO3 Phosphor Prepared by Spray Pyrolysis under Vacuum Ultraviolet (분무열분해 공정에 의해 합성된 유로피움이 도핑된 YBO3 형광체의 진공자외선 하에서의 발광 특성)

  • Koo, Hye-Young;Kang, Yun-Chan
    • Korean Journal of Materials Research
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    • v.16 no.8
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    • pp.485-489
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    • 2006
  • The preparation conditions of $YBO_3$:Eu phosphor particles having the maximum photoluminescence intensity under vacuum ultraviolet in the spray pyrolysis were optimized. The $YBO_3$:Eu phosphor particles prepared from spray solution with stoichiometric amount of boric acid had the maximum photoluminescence intensity. The $YBO_3$:Eu phosphor particles with pure phases were formed at low post-treatment temperatures because of fast reaction of yttrium and boron components without volatilization of boron component. The prepared $YBO_3$:Eu phosphor particles by spray pyrolysis had fine size, narrow size distribution and regular morphology. The photoluminescence intensity of the prepared $YBO_3$:Eu phosphor particles under vacuum ultraviolet was 103% of the commercial $(Y,Gd)BO_3$:Eu phosphor particles.

Zn2SiO4:Mn Phsophor Particles Prepared by Flame Spray Pyrolysis (화염분무열분해 공정에 의해 합성되어진 Zn2SiO4:Mn 형광체)

  • Kang Y. C.;Sohn J. R.;Jung K. Y.
    • Korean Journal of Materials Research
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    • v.14 no.8
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    • pp.600-606
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    • 2004
  • $Zn_{2}SiO_{4}:Mn$ 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.

Synthesis of Homogeneous La0.8Sr0.2CrO3 Powders Using an Ultrasonic Spray Pyrolysis Method

  • Kim, Chang-Sam;Hwang, Seong-Ik;Kim, Shin-Woo
    • Journal of the Korean Ceramic Society
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    • v.44 no.5
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    • pp.148-150
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    • 2007
  • A process to synthesize $La_{0.8}Sr_{0.2}CrO_3$ (LSC), which is a promising material for use as a separator in a soild oxide fuel cell, is investigated in this study. LSC powders without secondary Phases could be synthesized with ultrasonic spray pyrolysis and a heat treatment at $1200^{\circ}C$ for 20 h; however, it showed an average diameter of $0.6{\mu}m$ with a wide particle size distribution. On the other hand, LSC powders synthesized with spray pyrolysis at $800^{\circ}C$, heat-treated at $900^{\circ}C$ for 5 h, ball-milled and finally heat-treated again at $1200^{\circ}C$ for 20 h showed a smaller average diameter of $0.3{\mu}m$ and narrower size distribution. Very few particles above $0.5{\mu}m$ were found. Thus, a proper combination of the heat treatment and milling process after spray pyrolysis it determined to be very important in synthesizing fine and uniform LSC perovskite powders.