Yogesh Vohra, professor and university scholar at the University of Alabama at Birmingham (UAB) Department of Physics, is creating thin crystal films of new materials. With this method, Vohra is trying to create materials that are close to diamond hardness and can survive high pressure, temperature, and corrosive environments. Diamonds oxidize at temperatures greater than 1112ºF (600ºC) and they react with ferrous metals, so Vohra wants to design materials that overcome the shortcomings of the diamond. Dr. Vohra was able to synthesize a film of boron-rich-boron-carbide that has 37% the hardness of a diamond and is also an insulator.
The newly created material has 50 atoms of boron and 2 atoms of carbon (B50C2) in each subunit of the crystal. The two carbon atoms are precisely placed in the subunit. Vohra and his team grew B50C2 in a microwave plasma chemical vapor deposition system which uses 90% hydrogen gas and 10% B2H6 and parts per million carbon. The samples were grown at an atmospheric pressure equal to that of 15 miles above the earth and the temperature was 1382ºF (750ºC).
"Boron-rich boron-carbide materials synthesis by chemical vapor deposition methods continues to be relatively unexplored and a challenging endeavor," Vohra said. "The challenge is to find the correct set of conditions that are favorable for the growth of the desired phase. Our present studies provide validation of the density functional theory in predicting stable crystal structure and providing a metastable synthesis pathway for boron-rich boron-carbide material for applications under extreme conditions of pressure, temperature and corrosive environments."
Vohra reported his work in the journal, Scientific Reports.