• 제목/요약/키워드: Coprecipitation

검색결과 291건 처리시간 0.024초

Modified Oxalate Process에 의한 (Ba,Pb)$TiO_3$ 분말합성 및 특성에 관한 연구 (A Study on the Synthesis and Properties of (Ba,Pb)$TiO_3$Powder by Modified Oxalate Process)

  • 최병현;이미재;박선미
    • 한국세라믹학회지
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    • 제33권7호
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    • pp.743-754
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    • 1996
  • In this study (Ba1-xPbx)TiO3 was synthesized by modified oxalate process in order to prevent vaporization of PbO through low temperature synthesis climinate Cl ion reproducibly substitute Pb for by and uniformly distribute ion (Ba1-xPbx)TiO3 was synthesized by coprecipitation of lead acetate barium acetate and ammonium titanyl oxalate have been used as starting materials. The substitution of Pb for Ba was reproducibly possible synthetic temperature of perovskite structure becomes lowed as the Pb concentration increases and fine partic-les (specific surface are :7.2 cm2/g) were obtained, BaTiO3 powders calcined at 90$0^{\circ}C$ for 3 hours were cubic from in XRD analysis and as Pb content was increases evident split of tetragonal peaks could be observed The optimum conditions to synthesize (Ba,Pb)TiO3 powder are the followings ; synthesis temperature (5$^{\circ}C$)

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공심법과 (Sr-Ti)수산염에 의한 고순도의 $SrTiO_3$ 합성에 관한 연구 (Preparation of High Purity $SrTiO_3$ by Coprecipitation and Strontium Titanyl Oxalates)

  • 이종권;이병하
    • 한국세라믹학회지
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    • 제20권2호
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    • pp.107-114
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    • 1983
  • Formation of Strontium titanate from the products of coprecipitation takes place at 110$0^{\circ}C$ which is 200-30$0^{\circ}C$ lower than that from mechanical mixtures of $SrCO_3$ and $TiO_2$. This is apparently due to the nature of the compounds formed by the reaction of mixtures of aqueous solutions of $SrCl_2$ and $TiCl_4$ with an ammoniacal solution of ammoni-um carbonate and ammonium hydroxide. A procedure is described for preparing strontium titanyl oxalate tetrahydrate in the several mole ratio of $TiCl_4$ to $SrCl_2$. STrontium titanyl oxalates decompose to titanate at elevated temperature. The coprecipitates and the fired specimen were subjected to examined thermal and X-ray analyses and microstruc-ture by SEM.

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Synthesis and Dispersion Stabilization of Indium Tin Oxide Nanopowders by Coprecipitation and Sol-Gel Method for Transparent and Conductive Films

  • Cho, Young-Sang;Hong, Jeong-Jin;Kim, Young Kuk;Chung, Kook Chae;Choi, Chul Jin
    • 대한금속재료학회지
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    • 제48권9호
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    • pp.831-841
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    • 2010
  • Indium tin oxide (ITO) nanopowders were synthesized by coprecipitation and the sol-gel method to prepare a stable dispersion of ITO nano-colloid for antistatic coating of a display panel. The colloidal dispersions were prepared by attrition process with a vibratory milling apparatus using a suitable dispersant in organic solvent. The ITO coating solution was spin-coated on a glass panel followed by the deposition of partially hydrolyzed alkyl silicate as an over-coat layer. The double-layered coating films were characterized by measuring the sheet resistance and reflectance spectrum for antistatic and antireflective properties.

Photoluminescence of the Mn-doped ZnGa₂O₄ Phosphors Prepared by Coprecipitation of Metal Salts

  • 고중곤;박희동;김동표
    • Bulletin of the Korean Chemical Society
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    • 제20권9호
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    • pp.1035-1039
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    • 1999
  • Manganese-activated zincgallate (Zn1-xMnxGa2O4) phosphor as a green phosphor was readily prepared by coprecipitation in aqueous basic solution of metal salts. The obtained product converted to amorphous zincgallate even at 300℃, followed by crystallization at 1000 ℃. The pyrolyzed phosphor showed fine particle, then reduction treatment at 900 ℃ changed into homogeneous shape with slight grain growth(particle size less than 0.5 mm). The photoluminescence characteristics of the zincgallates have been investigated as a function of dopant concentrations, reducing atmospheres and temperatures. Under UV excitation the phosphors displayed the highest green emission efficiency at 504 nm when the specimen oxidized at 1000 ℃ was reduced at 900 ℃ in a mild hydrogen atmosphere (97% N2, 3% H2) with a flow rate of 100 ml/min.