Production of alpha aluminium oxide single crystal - which has a circular cross section, by drawing from an aluminium oxide melt contg. chromium-iron-, or magnesium oxide

摘要

The pptn. of alpha Al2O3 single crystals comprises pulling a rod of crystal nucleus from a melt. Solid alpha Al2O3 single crystal with R-plane orientation and of circular cross-section is produced by (a) melting Al oxide by heating to 2040 degrees C, (b) introducing a rod of crystal nucleus of alpha-Al oxide into the melt (c) maintains an inert atm. above the melt, (d) pulling the rod out of the melt so that alpha Al oxide material solidifies and crystallises on the rod forming a solid single crystal product of circular cross section, growing in length whereby the growth axis coincides with the longitudinal axis of the rod. The R-plane orientation is obtd. by using a melt of Al oxide contg. an effective amt. of at least one oxide such as Cr-, Fe-, and Mg oxide and 90-20,000 ppm of corresponding metal ions, and by introducing, as inoculating rod, a single crystal of alpha Al oxide so that the longitudinal axis lies at right angles to the R-plane of the rod. Used for passive substrates in the production of electronic circuits.