UChicago PME Materials Special Seminar- Rodney S. Ruoff

CARBON AND BORON NITRIDE MATERIALS: BASIC SCIENCE AND BROADER IMPACT 

We have discovered some quite interesting things about the macroscale strength of single crystal graphene. Many materials exhibit very high strength including ideal strength values, at microscale. We have CVD-grown single crystal and large area graphene (SCG) on Cu(111) and Ni(111) substrates. The centimeter-length scale tensile strength, strain-at-failure, and toughness modulus, are quite literally “out of this world” with strength values 5x to 6x that of the highest strength macroscale material commercially available. Both the basic science and practical applications of macroscale SCG tensile mechanics are extremely intriguing. Ruoff will also outline the macroscale strength possibilities for single crystal hBN. Diamond & graphite are essentially isoenergetic at STP (298K, 1 atm) as are hexagonal-boron nitride (hBN) & cubic boron nitride (cBN), and the same is true at higher temperatures. And yet there is a perception that it ‘must be’ more difficult to form diamond, and also cubic boron nitride, than graphite and hBN, respectively. Why? Because to date, this has been true. Also, on Earth there seems to be much more natural graphite than natural diamond, and there is (now) much more synthetic graphite annually produced than synthetic diamond. But must this always be so, going forward? Supported by the Institute for Basic Science (IBS-R019D1). Hosted by Junhong Chen