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Tracy Hall (1919-) is an American physical chemist who was one of the first to synthesize diamond, using a press of his own design.
Additional recommended knowledge
Tracy Hall was born in Ogden, Utah in 1919. His full name is Howard Tracy Hall, but he often uses the name H. Tracy Hall or, simply, Tracy Hall. He is a descendent of Utah pioneers who were devout Mormons. Tracy grew up on a farm in Marriott, Utah. An excellent student, when still in the fourth grade, he announced his intention to work for General Electric. He attended Weber College for two years, and married Ida-Rose Langford in 1941. He went to the University of Utah in Salt Lake City, where he received his B. S. degree in 1942 and an M. S. in the following year. For the next two years, he served as an ensign in the U. S. Navy. He returned to the University of Utah in 1946, where he was Henry Eyring's first graduate student. and was awarded his Ph. D. in physical chemistry in 1948. Two months later he realized his childhood dream by starting work at the General Electric Research Laboratory in Schenectady, New York. He joined a team focussed on synthetic diamond making, code named "Project Superpressure" headed by an engineer, Anthony Nerad.
As with many important inventions, the circumstances surrounding Hall's synthesis is the object of some controversy. What is undoubted is that he produced synthetic diamond in a press of his own design on December 16, 1954 and that he could do it over and over in the following weeks. What is also undoubted is that Hall was one of a group of about a half dozen of researchers who had focused on the syntheses for almost four years. These years had seen a succession of failed experiments, an increasingly impatient management, and a complex blend of sharing and rivalries among the researchers. (The first synthetic diamonds were produced by ASEA in Västerås, Sweden in 1953.)
Hall's success, in his telling of the story, came about because of his determination to go his own way with a radical redesign of the press, which employed a doughnut-shaped binding ring (the belt) which confined the sample chamber and two curved and tapered pistons which pressed on the sample chamber. He "bootlegged" the machining of the first hardened steel version of this press, which showed some promise, and eventually got management to approve the construction of it in the tougher, much more expensive Carboloy (tungsten carbide dispersed in cobalt, also known as Widia). However, his experiments were "relegated" (Hall claimed) to a smaller, antique, leaky 400 ton press, rather than a more expensive and new thousand ton press used by other members of the team.
The composition of the starting material in the sample chamber, catalyst for the reaction, and the required temperature and pressure were little more than guesses. Hall used iron sulfide and a form of powdered carbon as the starting material, with tantalum disks to conduct the electricity into the cell for heating it. The experiment was conducted at about 100,000 atmospheres, 1600 °C and took about 38 minutes. (Hazen, p 125) Upon breaking open the sample, clusters of diamond octahedral crystals were found on the tantalum metal disks, which apparently acted as a catalyst.
Hall left GE in 1955 and became a full professor of Chemist and director of research at Brigham Young University. Three years later, he invented a new type of press, the tetrahedral press.
He was granted 19 patents in his career. Some especially notable ones were:
Hazen, Robert M. The Diamond Makers Cambridge (1999) ISBN 0-521-65474-2.]
Categories: Physical chemists | Refractory materials | Gemstones | Synthetic minerals
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Tracy_Hall". A list of authors is available in Wikipedia.|