Al<sub>2</sub>O<sub>3</sub>-Nd<sub>2</sub>O<sub>3</sub>系の高温状態図

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  • Phase diagram of the system Al2O3-Nd2O3 at high temperatures.
  • Al2O3-Nd2O3系の高温状態図〔英文〕
  • Al2O3 Nd2O3ケイ ノ コウオン ジョウタイズ エイブン

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The liquidus temperature of the Al2O3-Nd2O3 system was measured from the cooling curve of specimens by the specular reflection method with a heliostat type solar furnace. Quenched specimens from the melt were examined by X-ray diffraction technique, petrographic microscopy and chemical analysis.<br>The single phase of NdAlO3 with the perovskite structure was obtained by heating at 1300 and 1600°C in an electric resistance furnace, and also by cooling the specimen fused in the solar furnace.<br>The reversible phase transition of NdAlO3 between the rhombohedral and cubic forms was also confirmed at about 1100°C by the high temperature X-ray diffractometry. The lattice parameters of the rhombohedral phase were a0=5.351Å, α=60°10' at 1075°C, and that of the cubic phase was a0=3.792Å at 1150°C. The variation of unit cell volume ΔV was therefore only 0.42 percent.<br>The refractive indices of NdAlO3 were obtained as γ=2.040±0.002, α=2.030±0.002.<br>The presence of Nd2O3⋅11Al2O3 (β-Al2O3 type) was also observed. However, in a fused specimen of Nd2O3⋅11Al2O3 composition, Nd2O3⋅11Al2O3 was not formed as a single phase but always coexisted with NdAlO3.<br>The lattice parameters of the Nd2O3⋅11Al2O3 phase were a0=5.55Å, c0=22.03Å, c/a=3.97.<br>A tentative phase diagram for the Al2O3-Nd2O3 system at high a temperature was presented.<br>The phase diagram shows two eutectics points at 1720°C with 23 mole percent Nd2O3, and at 1850°C with 80 mole percent Nd2O3 composition.<br>The cooling curves of Nd2O3 showed exothermic peaks related to solid state phase transformations below the solidification point.

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  • 窯業協會誌

    窯業協會誌 85 (978), 90-95, 1977

    公益社団法人 日本セラミックス協会

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