二重るつぼ法によるBi_2O_3(Nb_2O_5)-6Bi_2O_3・SiO_2共晶融液の一方向凝固

概要

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An eutectic melt in the system (Bi_2O_3)_<9.85>(Nb_2O_5)_<8.15>-6Bi_2O_3・SiO_2(Ref.1) was unidirectionally solidified in double crucibles, in which a pin hall was made at the center of the bottom of the upper one and a seed crystal was placed at the center of the bottom of the lower one (Fig.1) . A temperature gradient of 100℃/cm and a solidification rate of 0.5 mm/h were maintained during the solidification in a temperature gradient furnace having SiC heating elements at the top and a water cooled copper jacket at the bottom. The obtained ingot showed a uniform structure throughout the ingot, in which fibrous crystals of δ-(Bi_2O_3)_<0.85> (Nb_2O_5)_<9.15> 3.8 μm in diameter were embedded in parallel in a matrix of γ-6 Bi_2O_3・SiO_2 single crystal (Figs. 2 and 3). This structure was in contrast to that obtained with a single crucible (Ref.1), in which orientation of the fibrous crystals varied depending on the location (Fig. 2b) . A transverse thin section of the ingot obtained with the double crucibles showed a high optical transmission like an optical fiber array (Fig.5) . Then, this may be useful for applications such as screen of a cathode ray tube of high resolution.
社団法人日本セラミックス協会の論文
1988-03-01