Tracy Hall

Howard Tracy Hall (October 20, 1919 – July 25, 2008) was an American physical chemist and the first person who grew a synthetic diamond according to a reproducible, verifiable and witnessed process, using a press of his own design.

Early life

Tracy Hall was born in Ogden, Utah in 1919. His full name was Howard Tracy Hall, but he often used the name H. Tracy Hall or, simply, Tracy Hall. He was 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.

The invention

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.

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. Harv|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.

Later Years

Hall left GE in 1955 and became a full professor of chemistry and Director of Research at Brigham Young University. Three years later, he invented a new type of press, the tetrahedral press. For many years, the tetrahedral press was displayed in the Eyring Science center on campus at BYU.

Recognition

*In 1970 he was awarded the Chemical Pioneers Award by the The American Institute of Chemists.
* In 1972 he was awarded the American Chemical Society Award for Creative Invention: "For being the first to discover a reproducible reaction system for making synthetic diamonds from graphite, and for the concept and design of a super high pressure apparatus which not only made the synthesis possible, but brought about a whole new era of high pressure research."
* The 1994 Governor's Medal for Science and Technology

ee also

* [http://www.htracyhall.org/HTracyHall/History/bio.htm] Tracy Hall biography.
* [http://www.htracyhall.org/HTracyHall/] papers and patents

Patents

He was granted 19 patents in his career. Some especially notable ones were:
*US patent|2947608 or [http://www.htracyhall.org/HTracyHall/pdf/p2947608.pdf] "Diamond Synthesis" Howard Tracy Hall, Aug. 2, 1960.
*US patent|2947610 or [http://www.htracyhall.org/HTracyHall/pdf/p2947610.pdf] "Method of Making Diamonds" Howard Tracy Hall, Herbert M. Strong and Robert H. Wentorf, Jr., Aug. 2, 1960.
*US patent|3159876 or [http://www.htracyhall.org/HTracyHall/pdf/p3440687.pdf] "High Pressure Press" Howard Tracy Hall, Dec. 8, 1964.

References

Hazen, Robert M. "The Diamond Makers" Cambridge (1999) ISBN 0-521-65474-2.