擬ブルッカイト型固溶体の生成に及ぼすＺｎ｀２＋´，Ｎｉ｀２＋´及びＣｒ｀３＋´の位置選択性の影響

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  • Influence of Site Preference of Zn<sup>2+</sup>, Ni<sup>2+</sup> and Cr<sup>3+</sup> upon the Formation of Pseudobrookite Type Solid Solutions
  • ギ ブルッカイトガタ コヨウタイ ノ セイセイ ニ オヨボス Zn2 + Ni

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説明

The terahedral site preference of Zn2+ and the octahedral site preference of Ni2+ and Cr3+ are significantly stronger than those of any other divalent or trivalent cations found in pseudobrookite structure such as Mg2+, Fe2+, Co2+, Al3+ and Fe3+. The purpose of this paper is to investigate the influence of site preference of Zn2+, Ni2+ and Cr3+ upon the formation of pseudobrookite type solid solutions.<br>Specimens are prepared by calcining a mixture of each oxide, hydroxide or basic carbonate for 1-20h at 1100°-1550°C. The formation of single phase solid solution is examined by X-ray analysis, and the lattice parameters are calculated. The absorptions of Co2+, Ni2+ and Cr3+ in the pseudobrookite structure are discussed by measuring the spectral reflectance. The results are summarized as follows.<br>1) Calcined products with the composition of ZnO2TiO2, NiO2TiO2 and Cr2O3TiO2 are confirmed by X-ray analysis to be the phase assemblage of 2ZnOTiO2+TiO2, NiOTiO2+TiO2 and Cr2O3 2TiO2+Cr2O3, respectively.<br>2) Continuous solid solutions are obtained in xCoO(1-x)MgO2TiO2. The phase of CoO2TiO2 being unstable towards decomposition into the phase assemblage of CoOTiO2+TiO2 below 1100°C, quenching is necessary to obtain the single phase of CoO2TiO2.<br>3) Since Co2+ shows a tetrahedral site preference resulted from its electronic configuration 3d7, and occupies also an octaheral site in pure CoO, reflectance curve of Co2+ in pseudobrookite structure resembles simultaneously to that of Co2+ in ilmenite structure (CoO6) and in wurtzite structure (CoO4).<br>4) The incorporation of Zn2+ into MgO2TiO2 on substitution of Mg2+ for Zn2+, is ca. 80mol%.<br>5) The pseudobrookite structure is maintained on substitution of ca. 50mol% of Mg2+ for Ni2+ in MgO2TiO2.<br>6) Since Ni2+ shows a strong octahedral site preference resulted from its electronic configuration 3d8, and occupies an octahedral site preferentially, the reflectance curve of Ni2+ in pseudobrookite structure resembles to that of Ni2+ in ilmenite structure (NiO6), but differs from that of Ni2+ in the tetrahedral site in spinel and phenacite structures.<br>7) The pseudobrookite structure is maintained on substitution of ca. 40mol% of Co2+ for Zn2+ or Ni2+ in CoO 2TiO2.<br>8) The incorporations of Cr3+ into Al2O3TiO2 and Fe2O3TiO2 on substitution of Al3+ or Fe3+ for Cr3+ are only ca. 10mol%.

収録刊行物

  • 窯業協會誌

    窯業協會誌 90 (1040), 180-187, 1982

    公益社団法人 日本セラミックス協会

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