Phase equilibria in the Ln2O3-V2O3-V2O5 (Ln=Eu and Yb) systems at 1200.DEG.C.
スポンサーリンク
概要
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Phase equilibria in the systems, Eu<SUB>2</SUB>O<SUB>3</SUB>–V<SUB>2</SUB>O<SUB>3</SUB>–V<SUB>2</SUB>O<SUB>5</SUB> and Yb<SUB>2</SUB>O<SUB>3</SUB>–V<SUB>2</SUB>O<SUB>3</SUB>–V<SUB>2</SUB>O<SUB>5</SUB>, were established at 1200 °C by changing the oxygen partial pressure from －0.68 (air) to －13.00 atm in terms of log<I>P</I>o<SUB>2</SUB>. In the Eu<SUB>2</SUB>O<SUB>3</SUB>–V<SUB>2</SUB>O<SUB>3</SUB>–V<SUB>2</SUB>O<SUB>5</SUB> system, 0.81Eu<SUB>2</SUB>O<SUB>3</SUB>·0.19V<SUB>2</SUB>O<SUB>5</SUB> (Eu<SUB>1.62</SUB>V<SUB>0.38</SUB>O<SUB>3.38</SUB>) was stable; in the Yb<SUB>2</SUB>O<SUB>3</SUB>–V<SUB>2</SUB>O<SUB>3</SUB>–V<SUB>2</SUB>O<SUB>5</SUB> system, a new compound Yb<SUB>7</SUB>V<SUB>3</SUB>O<SUB>16</SUB> was stable; and in both systems Ln<SUB>2</SUB>O<SUB>3</SUB>, LnVO<SUB>4</SUB>, LnVO<SUB>3</SUB>, V<I><SUB>n</SUB></I>O<SUB>2<I>n</I>－1</SUB>(<I>n</I>=2–7), and VO<SUB>2</SUB> were stable under the present experimental conditions. On the basis of the established phase diagrams, Gibbs energies of these reactions, 31/50 Eu<SUB>2</SUB>O<SUB>3</SUB>+19/50 EuVO<SUB>3</SUB>+19/100 O<SUB>2</SUB>= Eu<SUB>1.62</SUB>V<SUB>0.38</SUB>O<SUB>3.38</SUB>, EuVO<SUB>3</SUB>+1/2O<SUB>2</SUB>= EuVO<SUB>4</SUB>, 2 Yb<SUB>2</SUB>O<SUB>3</SUB>+ 3 YbVO<SUB>3</SUB>+1/2O<SUB>2</SUB>=Yb<SUB>7</SUB>V<SUB>3</SUB>O<SUB>16</SUB>, Yb<SUB>7</SUB>V<SUB>3</SUB>O<SUB>16</SUB>+O<SUB>2</SUB>=2 Yb<SUB>2</SUB>O<SUB>3</SUB>+ 3 YbVO<SUB>4</SUB>, and YbVO<SUB>3</SUB>+1/2O<SUB>2</SUB>=YbVO<SUB>4</SUB>, were determined to be －58.9, －126.0, －134.0, －210.0, and －117.7 kJ respectively. EuVO<SUB>4</SUB>, Eu<SUB>1.62</SUB>V<SUB>0.38</SUB>O<SUB>3.38</SUB>, YbVO<SUB>4</SUB>, Yb<SUB>7</SUB>V<SUB>3</SUB>O<SUB>16</SUB>, V<SUB>2</SUB>O<SUB>3</SUB>, and VO<SUB>2</SUB> have nonstoichiometric compositions.
著者
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KATSURA Takashi
Department of Chemistry
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Kitayama Kenzo
Department Of Applied Chemistry And Biotechnology
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Sou Hidehiko
Department of Chemistry, Faculty of Science, Tokyo Institute of Technology
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