To date, the EFG process has produced ribbons up to 6 feet in length. The ribbons, typically 1 inch in width and about 0.01 inch thick, can be pulled at a rate of 1 inch per minute. Current work at Tyco is aimed at producing 50- to 100-foot ribbons, Dr. Mlavsky says. He thinks this stage could take another year. After that, the final milestone in ribbon production would be to grow many ribbons simultaneously and continuously from a single apparatus. Dr. Mlavsky believes that the prognosis for this accomplishment is very good, since the company already has grown multiple continuous crystals of other materials, notably sapphire, by this technique. Tyco's work on the EFG process dates back nine years. The first efforts concentrated on sapphire material (single-crystal aluminum oxide). The result was a patented, commercial process that is in use at Tyco and at a number of other firms on license to produce single-crystal sapphire for a variety of uses. The first such commercial application of the EFG process was a sapphire arc tube for sodium vapor lamps, developed by Tyco and produced by Corning Glass Works under license. Licenses this year for the EFG process have gone to RCA Corp. and to Kyoto Ceramic Co. in Japan. Three years ago, Tyco extended the EFG process to silicon material. The first goal, quickly achieved, was to grow silicon ribbons of a geometry suitable for use in solar cells. The second step was to produce silicon ribbon of high enough quality for the production of solar cells with about 10% efficiency. This, too, was achieved. Next came the improvement in ribbon lengths leading to the present work on continuous production. The silicon ribbon work also brought other forces into play to support Tyco's process development. Dr. Bruce Chalmers, professor of metallurgy at Harvard University, has supplied theoretical work on crystal growth, including calculations of the dynamics of the growth process. This research has been supported by two years of government funds—$300,700 to Tyco and Harvard from the National Science Foundation and $265,000 to Tyco from the National Aeronautics and Space Administration's Jet Propulsion Laboratory, Pasadena, Calif. An eventual low-cost solar cell from the EFG process may never replace conventional fuels and nuclear power, Dr. Mlavsky concedes. However, the new cell could be a means of augmenting conventional power. Uses could range from a few watts of power for a remotely located emergency transmitter to moderate-sized installations in houses and commercial buildings to a large "solar farm" feeding power into an electric power grid when the sun is shining. The EFG process is not yet fully
proved, Dr. Mlavsky emphasizes. However, the technology is promising and carries the advantage of relatively low development cost compared to nuclear power development. "The reduction to manufacture of the Tyco technology for solar cells will provide an important source of fuel-free, pollution-free electricity even if the long-term cost goals are never fully achieved."
Spevack wins suits over heavy water Perseverance is a word that certainly applies to Jerome S. Spevack, president of Deuterium Corp., White Plains, N.Y. The inventor of the dualtemperature heavy-water production process has been to court against the U.S. Government off and on since 1957, seeking first to receive protection then compensation for use of his invention. Late last month came the ultimate settlement: nearly $1.5 million from the U.S. Government and the Atomic Energy Commission. The current settlement is a consolidation in response to two suits filed by Mr. Spevack and Deuterium Corp. in 1965 and one in 1971 with the U.S. Court of Claims, seeking compensation on the basis of two patents and applications for related additions and extensions. The settlement was made by court order after two of the three suits had been to trial. Mr. Spevack and Deuterium Corp. will receive two payments. A payment of $995,000 will be made by the U.S. Government to cover all past liability of the Government claimed in the litigation. A second payment of $500,000 will be made by AEC under a license agreement allowing the Government to continue to use the inventions covered by the patents and applications for production of up to 250 tons of heavy water per year at AEC's Savannah River, S.C., plant for whatever use it currently is being made. Under the license agreement, the Government has the option to convert its license to one for use of the inventions in new government-owned plants but limited to production of heavy water solely for use by the Government itself—a provision that protects the Government against any shortages in an emergency. Besides the money, Deuterium Corp. and Mr. Spevack receive the irrevocable royalty-free right to unlimited use of the inventions of all patents and patent applications owned or controlled by AEC for concentration of any isotopes by the dual-temperature process and/or for the production of heavy water. The two patents on which Mr. Spevack staked his claim are U.S. 2,895,803, for an isotope concentration system, and U.S. 3,142,540, for a dualtemperature exchange apparatus. In addition, the case was based on 10 ap-
plications for additions and continuations, all of which are pending, although some have been allowed. There were also three applications for unrelated improvements that are still pending. According to Mr. Spevack, there have been improvements and modifications in the heavy-water production process over the years. But the basic technology is still the same as that covered by his patents. The process makes use of a hot tower and a cold tower in each stage, with hydrogen sulfide as a deuterium transfer agent. In each tower, water flows down and hydrogen sulfide flows up. In the hot tower, hydrogen sulfide picks up deuterium from the water by isotope exchange, becoming enriched in deuterium. Some of this enriched hydrogen sulfide goes to the hot tower of the next stage, where it is enriched further. The rest goes to the cold tower of the same stage, where water picks up deuterium from the hydrogen sulfide and becomes enriched as it goes through the tower. Some of the enriched water goes to the cold tower of the next stage where it is enriched further. The rest goes through the hot tower, from which the depleted water is discharged to waste. The net result of the flows is that enriched water comes from the cold tower and depleted water from the hot tower. The hydrogen sulfide acts only as a transfer agent and exhibits no net change in deuterium content. Mr. Spevack was employed in the Manhattan Engineering District in the 1940's, during which time he obtained and assigned to the Government a patent for an isotope-concentration process. Later, while self-employed, the chemical engineer conceived a new system. An AEC decision in 1957 to declassify Mr. Spevack's process as part of a major declassification program led to Mr. Spevack's first appearance in court to get an injunction to prevent AEC from disclosing the process before he had a chance to get U.S. and foreign patent protection. That case, fought to the Supreme Court, with the American Chemical Society supporting Mr. Spevack as amicus curiae, resulted in a 1959 ruling in Mr. Spevack's favor. Receiving his patent, he later filed the 1965 suit for compensation. The founder of Deuterium Corp., Mr. Spevack was also president of Deuterium of Canada, which was involved with a heavy-water plant at Glace Bay, N.S. (that later achieved notoriety through corrosion problems resulting from an attempt to use sea water). Deuterium Corp. has had no involvement in production since 1968, when it sold its interest in the Canadian plant to Nova Scotia. Now, Mr. Spevack says, Deuterium Corp.'s objective is to get into heavywater production in the U.S. as soon as possible. July 29, 1974 C&EN
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