Crystal Habits of Corundum Single Crystals Grown in Cryolite Flux

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J. Korean Ceram. Soc. > Volume 29(6); 1992 > Article

Journal of the Korean Ceramic Society 1992;29(6): 463.

빙정식 융제로 성장한 Corundum 단결정의 결정형

장진욱, 이태근, 정수진

서울대학교 무기재료공학과

Crystal Habits of Corundum Single Crystals Grown in Cryolite Flux

ABSTRACT

Corundum single crystals were grown in cryolite flux with the composition of Na3AlF6:Al2O3=80:20 wt%. This mixture was melted at 115$0^{circ}C$, followed by slow cooling at a rate of 2$^{circ}C$/hr to 96$0^{circ}C$. And by adding of La2O3 to the flux, the change of crystal forms were observed. Crystal forms of corundum grown in cryolite flux had the habits of hexagonal plate which consist of well developed {0001} face and small {101} face. As La2O3 was added and its content was increased, {223} and {110} faces were developed, and crystal habits of equidimensional forms changed into hexagonal prism form. In a charge of 8 mole% B2O3, Al2O3:La2O3=15:1, transparent corundum single crystals of equent form were grown. As the content of B2O3 was increased, twineed crystals which have twin law of 2-fold parallel to [0001], and composition plane of (110) were grown.