Abstract
Borides of high electron density metals such as Os show promise as hard materials. Arc-melting elemental osmium and boron under an argon atmosphere produced osmium diboride (OsB2). Both a Vickers diamond microindenter and a Berkovich nanoindenter were used to measure hardness. Vickers microindentation indicates that the hardness of OsB2 increases significantly with decreasing applied load. The average hardness reaches approximately 37 GPa as the applied load is lowered to 0.245 N. The hardness is found to be highly dependent on the crystallographic orientation. For the {010} grains, along the 〈100〉 direction, the average hardness is significantly higher than that in the orthogonal 〈001〉 direction. Cracks associated with pop-in events in the nanoindentation load–displacement curves are observed in the {010} grains. The measured Young’s modulus of OsB2 is 410 ± 35 GPa, which is comparable to that obtained from first-principles calculations.
Similar content being viewed by others
References
J. Haines, J.M. Leger G. Bocquillon: Synthesis and design of superhard materials. Annu. Rev. Mater. Res. 31, 1 2001
H. Cynn, J.E. Klepeis, C-S. Yoo D.A. Young: Osmium has the lowest experimentally determined compressibility. Phys. Rev. Lett. 88, 135701 2002
T. Kenichi: Bulk modulus of osmium: High-pressure powder x-ray diffraction experiments under quasihydrostatic conditions. Phys. Rev. B 70, 012101 2004
F. Occelli, D.L. Farber, J. Badro, C.M. Aracne, D.M. Teter, M. Hanfland, B. Canny B. Couzinet: Experimental evidence for a high-pressure isostructural phase transition in osmium. Phys. Rev. Lett. 93, 0955021 2004
R.B. Kaner, J.J. Gilman S.H. Tolbert: Designing superhard materials. Science 308, 1268 2005
C.P. Kempter: Further investigations of RuC and OsC. J. Chem. Phys. 41, 1515 1964
A.F. Young, C. Sanloup, E. Gregoryanz, S. Scandolo, R.J. Hemley H-K. Mao: Synthesis of novel transition metal nitrides IrN2 and OsN2. Phy. Rev. Lett. 96, 155501 2006
R.W. Cumberland, M.B. Weinberger, J.J. Gilman, S.M. Clark, S.H. Tolbert R.B. Kaner: Osmium diboride, an ultra-incompressible, hard material. J. Am. Chem. Soc. 127, 7264 2005
Z.Y. Chen, H.J. Xiang, J. Yang, J.G. Hou Q. Zhu: Structural and electronic properties of OsB2: A hard metallic material. Phys. Rev. B 74, 012102 2006
H. Gou, L. Hou, J. Zhang, H. Li, G. Sun F. Gao: First-principles study of low compressibility osmium borides. Appl. Phys. Lett. 88, 221904 2006
S. Chiodo, H.J. Gotsis, N. Russo E. Sicilia: OsB2 and RuB2, ultra-incompressible, hard materials: First-principles electronic-structure calculations. Chem. Phys. Lett. 425, 311 2006
M. Hebbache, L. Stuparevic D. Zivkovic: A new superhard material: Osmium diboride OsB2. Solid State Commun. 139, 227 2006
W.C. Oliver G.M. Pharr: An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J. Mater. Res. 7, 1564 1992
JCPDS No. 17-0370. International Center for Diffraction Data Newton Square, PA 2003
R.B. Roof Jr. C.P. Kempter: New orthorhombic phase in Ru–B and Os–B systems. J. Chem. Phys. 37, 1473 1962
B. Aronsson: Crystal structure of RuB2, OsB2, and IrB1.35 and some general comments on crystal chemistry of borides in composition range MeB–MeB3. Acta Chem. Scand. A 17, 2036 1963
P.M. Sargent: Microindentation Techniques in Science and Engineering edited by P. Blau and B. Lawn ASTM Ann Arbor, MI 1985 160
M.F. Doerner W.D. Nix: A method for interpreting the data from depth-sensing indentation instruments. J. Mater. Res. 1, 601 1986
H.Y. Chung, B. Weinberger, J.B. Levine, A. Kavner, J-M. Yang, S.H. Tolbert R.B. Kaner: Synthesis of ultra-incompressible superhard rhenium diboride at ambient pressure. Science 316, 436 2007
M. Hebbache: Shear modulus and hardness of crystals: Density-functional calculations. Solid State Commun. 113, 427 2000
M.B. Weinberger, R.W. Cumberland, J.B. Levine, N. Conil, A. Shahar, R.B. Kaner, S.H. Tolbert A. Kavner: Strength of osmium diboride under high pressure and nonhydrostatic stress. (unpublished)
I. Tanaka, F. Oba, T. Sekine, E. Ito, A. Kubo, K. Tasumi, H. Adachi T. Yamamoto: Hardness of cubic silicon nitride. J. Mater. Res. 17, 731 2002
T. Scholz, G.A. Schneider, J. Munoz-Saldana M.V. Swain: Fracture toughness from submicron derived indentation cracks. Appl. Phys. Lett. 84, 3055 2004
S.O. Kucheyev, J.E. Bradby, J.S. Williams, C. Jagadish M.V. Swain: Mechanical deformation of single-crystal ZnO. Appl. Phys. Lett. 80, 956 2002
D. Liu, M. Chelf K.W. White: Indentation plasticity of barium titanate single crystals: Dislocation influence on ferroelectric domain walls. Acta Mater. 54, 4525 2006
Acknowledgments
This work was funded by the National Science Foundation under Grant No. DMR-0453121 (R.B. Kaner). The authors thank Dr. J. Gilman, Dr. R. Cumberland, and Dr. E. Sung for their assistance with this research.
Author information
Authors and Affiliations
Corresponding authors
Rights and permissions
About this article
Cite this article
Chung, HY., Yang, JM., Tolbert, S. et al. Anisotropic mechanical properties of ultra-incompressible, hard osmium diboride. Journal of Materials Research 23, 1797–1801 (2008). https://doi.org/10.1557/JMR.2008.0221
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1557/JMR.2008.0221