フラックス法によるコランダム単結晶の合成

概要

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Single crystals of corundum containing a small amounts of various dopants (Cr^<3+>, Fe^<3+>, Ti^<4+>, La^<3+>, Nd^<3+>, Dy^<3+>, and Yb^<3+> oxides) were grown by the methods such as seeded (with or without lid) , seed rotation, top-seeded, and temperature alternating from a cryolite (Na_3 AlF_6) flux. Good crystals were obtained under the following conditions: growth temperature, 1050 ℃; temp. difference between baffle plate and seed crystal, about 0.5 ℃; temp, differ. (bottom-baffle) , less than 3 ℃; baffle aperture, 10〜15%; growth rate, less than 10 mg/hr; seed rotation, 30 rpm; dopant, 1〜3 wt% per flux weight. Crystal continuity from the seed to the new growth were achieved well using two steps temperature elevating method by which the surface of the seed crystal is dissolved slightly. Habit modifications of corundum crystals due to the kind of dopants were as follows : Cr_2O_3 or Fe_2O_3 doping, tabular crystals surrounded by the c (0001), r {1011^^-}, and n {2243^^-} planes; barrel-shaped crystals composed of the c (0001) and n {224^^-3} planes were synthesized by the TiO_2 dopant; using the rare earth dopants, hexagonal-prismatic crystals having the c and a {112^^-0} planes were obtained. Corundum crystals possessing the zonal structure which was caused by variation of the distribution coefficient were produced by the temperature alternaing method.
宝石学会(日本)の論文
1976-12-15