Method of purifying molten silica
AssigneeTSL Group PLC
InventorJohn A. Winterburn
Life of this patent
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Abstract
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.
Claims4
A method of improving the purity of melt contacting an inner wall of a vitreous silica containing vessel, wherein impurity ions in the melt are made to migrate into said inner wall and from the inner wall towards an outer wall of the vessel, by applying a polarising potential across said walls, the polarising potential being applied via the melt in a direction to cause impurity ions in the vitreous silica to migrate away from said inner wall while the vessel is maintained at a temperature above 1000.degree. C.
Dependencies are inferred from the claim text.