MAN-MADE DIAMONDS — SUITS 447 



rials, the properties of semiconductors at higli pressure, nuclear mag- 

 netic resonance in solids and liquids under pressure, the determination 

 of fixed points on the high-pressure scale, geochemical and geophysical 

 studies, a variety of thermodynamic approaches to the study of acti- 

 vated processes under high pressure, and scores of other seemingly 

 esoteric but inherently valuable research objectives. 



In more down-to-earth language, it might be said that — obviously — 

 it is possible to put many materials other than carbon into these cham- 

 bers and subject them to high pressure and high temperature for long 

 periods of time. Such possibilities provide a virtually infinite chal- 

 lenge for the research scientist. 



One of the first results of this kind of exploration was a new form of 

 boron nitride. Boron nitride, in its common form, has a structure very 

 similar to graphite, with boron and nitrogen replacing carbon in the 

 lattice. It is a slippery material so much like graphite in mechanical 

 properties that it is often called "white graphite," Boron nitride was 

 sufficiently intriguing to prompt Wentorf at our laboratory to try 

 superpressure techniques on this material. 



The result was spectacular : A completely new material never found 

 in nature (pi. 4, fig 1). "Borazon," as it was named, is in the same 

 range of hardness as diamond. As the photograph (pi. 4, fig. 2) shows, 

 it is the only material other than diamond that has ever been able to 

 scratch diamond. Because borazon is more oxidation-resistant than 

 diamond, we believe it w^ll eventually have important industrial 

 applications. In addition to borazon, more than 20 new forms of 

 matter have been created through superpressure research in the one 

 program with which I am most familiar. Principally, these are 

 chemical compounds, although in some cases they are single elements 

 converted into new crystalline arrangements. At present there is 

 considerable scientific excitement in the laboratory concerning evidence 

 w^hich points to the possibility of a completely new crystal form of 

 carbon. However, this w^ork is still incomplete, and requires con- 

 firmation. In the case of both germanium and silicon, we and other 

 workers in the field have identified some new high-density forms sub- 

 stantially different from the crystal structure which helps give these 

 materials their unique value as semiconductors. 



But this was to be mainly a story about carbon, that many-faceted 

 element which is so dominant in science and life. What is the future 

 for carbon as we continue to heat it and squeeze it and catalyze it ? 



We are gradually learning how to make larger and larger diamond 

 crystals — how to control the nucleation of crystal growth and achieve 

 bigger single crystals with fewer occlusions and imperfections. We 

 are learning how to keep unwanted atoms out of the carbon structure, 

 and it seems reasonable to hope that stronger, more perfect crystals 

 will result. Finally, we like to look at the phase diagram for carbon 



