• Title/Summary/Keyword: pure brookite

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Synthesis of Pure Brookite-type TiO2 Nanoparticles from Aqueous TiCl4 Solution with controlled Acidity by Precipitation Method (침전법으로 TiCl4 수용액의 산농도 조절을 통한 나노크기의 순수한 브루카이트상 이산화티타늄 분말 제조)

  • Lee, Jeong Hoon;Yang, Yeong Seok
    • Applied Chemistry for Engineering
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    • v.18 no.6
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    • pp.545-551
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    • 2007
  • HCl concentration, reaction temperature, and $Ti^{4+}$ concentration are the decisive factors in determining the structure of precipitates in the process of synthesis of $TiO_2$ particles from aqueous $TiCl_4$ solution by precipitation and the volumetric proportion of brookite phase in $TiO_2$ particles can be controlled by these factors. Pure brookite-type $TiO_2$ nanoparticles were synthesized by heating the aqueous $TiCl_4$ solution with no more than 1.0 M of $Ti^{4+}$, in which the concentration of HCl was kept in the range of about 2.53~6.41 M during reaction, at the temperature below $70^{\circ}C$ for 20 h. Also, Pure brookite was finally transformed to a rutile phase via an anatase phase through heat-treatment.

Influence of the Molar Ratio of Cl-total:Ti+4 on the Crystalline Structure in Preparation of TiO2 from Aqueous TiOCl2 Solution by Homogeneous Precipitation Method (균일침전법에 의한 이산화티타늄 제조공정에서 TiOCl2 수용액의 Cl-total:Ti+4의 몰 비율이 TiO2 결정구조에 미치는 영향)

  • Lee, Jeong Hoon;Yang, Yeong Seok
    • Applied Chemistry for Engineering
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    • v.16 no.6
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    • pp.785-789
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    • 2005
  • $TiO_2$ powders with rutile and brookite phases were synthesized through homogeneous precipitation of the aqueous $TiOCl_2$ solution, prepared from $TiCl_4$ and HCl solution, and their properties were characterized. Based on the analytical results appropriate molar ratios of ${Cl^-}_{total}:Ti^{+4}$ in precipitating solution for synthesis of pure rutile phase and a mixture of rutile and brookite phases were proposed. The volumetric proportion of brookite increased with increasing HCl concentration under a typical condition obtaining mixed phase of rutile and brookite. The brookite phase in the mixture was transformed to anatase phase by heat treatment at about $800^{\circ}C{\sim}850^{\circ}C$, and finally converted to rutile phase at $1000^{\circ}C$.