Osmium Diboride, An Ultra-Incompressible, Hard Material

• Published in: Journal of the American Chemical Society Vol. 127; no. 20; pp. 7264 - 7265
• Main Authors: Cumberland, Robert W, Weinberger, Michelle B, Gilman, John J, Clark, Simon M, Tolbert, Sarah H, Kaner, Richard B
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 25-05-2005
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja043806y

The need for wear- and scratch-resistant materials drives the quest for new superhard materials. In this work, we apply two design parameters to identify ultra-incompressible, superhard materialshigh valence electron density and high bond covalency. Our first example of such a material is OsB2. The bulk modulus of OsB2 was measured using in situ high-pressure X-ray diffraction and was determined to be in the range of 365−395 GPa. While this value is slightly less than that of the bulk modulus of diamond, due to the anisotropic crystal structure of OsB2, the axis compressibility in the orthorhombic c-direction is less than the axis compressibility found in diamond. OsB2 also scratches the surface of a sapphire window, indicating that the hardness of OsB2 exceeds 2000 kg/mm2.