A Century of Sapphire Crystal Growth

In Paris around 1890, A. V. L. Verneuil developed a flame fusion process to produce ruby and sapphire crystal. By 1900 there was brisk demand for ruby manufactured by Verneuil's method, which was used with little alteration for 50 years. From 1932-1953, S. K. Popov in the Soviet Union established a capability for manufacturing high quality sapphire crystal by the Verneuil process. In the U.S., under government contract during World War II, Linde Air Products Co. implemented the Verneuil process for making jewel bearings for precision instruments. In the 1960s and 1970s, the Czochralski process was implemented by Linde and its successor, Union Carbide, to make higher quality crystals for ruby lasers. Stimulated by a government contract for structural fibers in 1966, H. LaBelle invented edge-defined film-fed growth (EFG).

The Saphikon company, owned now by Saint-Gobain, evolved from this effort. Stepanov independently developed edge-defined film-fed growth in the Soviet Union. In 1967 F. Schmid and D. Viechnicki at the Army Materials Research Lab grew sapphire by the heat exchanger method (HEM). Schmid later established crystal systems, Inc. around this technology. Rotem Industries, founded in Israel in 1969, perfected the growth of sapphire crystal hemispheres and near-net-shape domes by gradient solidification. In the U.S., growth of near-net-shape sapphire domes was demonstrated by both the EFG and HEM methods in the 1980s but neither method became commercial. Today, domes in the U.S. are made by scooping sapphire boules with diamond-impregnated cutting tools. Commercial markets for sapphire crystal, especially in the semiconductor industry, are healthy and growing at the dawn of the 21st century.


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