Method and apparatus for purification of crystal material and for making crystals therefrom and use of crystals obtained thereby

US7344595B2 · kind B2 · utility

Assignee

• Schott AG · DE

Inventors

• Joerg Kandler · Cospeda, DE
• Lutz Parthier · Kleinmachnow, DE
• Thomas Kaufhold · Schnaittenbach, DE
• Gunther Wehrhan · Jena, DE
• Clemens Kunisch · Armsheim, DE

Key dates

• Filing date: Jan 24, 2005
• Grant date: Mar 18, 2008
• Expiry date: Jul 22, 2025

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T117/108
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

The method for producing single crystals includes drying crystal raw material by removing water, reaction of impurities with a scavenger, preferably a metal halide, and homogenizing the melt. The method is performed with the raw material in a melt vessel with a variable-sized through-going opening, in which drying occurs at 100° C. to 600° C. for at least 20 hours with a geometric conductance value for the through-going opening of 2.00 to 30.00 mm2; the reacting occurs at 600° C. to 1200° C. for at least nine hours with a geometric conductance value of 0.0020 to 0.300 mm2 and the homogenizing occurs at above 1400° C. for at least six hours with a geometric conductance value of 0.25 to 1.1 mm2. Alternatively the geometric conductance value is the same during drying, reacting and homogenizing and takes a value between 0.25 and 1 mm2.