QUARZGLAS.

摘要

PCT No. PCT/GB85/00499 Sec. 371 Date Jul. 7, 1986 Sec. 102(e) Date Jul. 7, 1986 PCT Filed Nov. 4, 1985 PCT Pub. No. WO86/02919 PCT Pub. Date May 22, 1986.An improved quality vitreous silica boby and/or improved quality product made at high temperature in a vitreous silica vessel is/are obtained by applying a polarizing potential across the boundary surfaces of the vitreous silica body or vessel to cause migration of impurity ions away from one of the boundary surfaces thereof. Single crystal silicon (10) of reduced alkali content is drawn from melt (12) in a vitreous silica crucible (14) with a polarizing voltage applied across the wall of the crucible.