Osmium (Os) is a dense, bluish-white transition metal belonging to the platinum group, recognized as the densest naturally occurring element. It exhibits remarkable mechanical and chemical stability, with a melting point of 3033 °C, a bulk modulus exceeding 460 GPa, and high resistance to corrosion and wear. These properties make osmium valuable for applications in high-performance alloys, electrical contacts, and catalysts.
Material Overview
Osmium crystallizes in a hexagonal close-packed (hcp) structure and has a measured density of 22.59 g/cm³ at room temperature, as confirmed by Arblaster (2023) and earlier by his 2013 study on osmium crystallography. The element retains its hcp phase up to pressures exceeding 770 GPa, according to Dubrovinsky et al. (2015), who found osmium to remain incompressible under static pressures surpassing any other known elemental solid. Dynamical mean-field theory suggested electronic topological transitions in its Fermi surface at around 150 GPa, highlighting osmium’s quantum resilience under extreme compression.
Its yield strength is among the highest ever recorded for a pure metal—up to 10 GPa at 26 GPa applied pressure—based on in situ X-ray diffraction experiments by Weinberger et al. (2008). These characteristics make osmium a benchmark for ultra-hard, incompressible materials. Additionally, osmium diboride (OsB?), synthesized via arc melting, reaches hardness values up to 37 GPa and a Young’s modulus of 410 ± 35 GPa (Chung et al., 2008), surpassing most transition metal borides. These advances demonstrate osmium’s potential in the design of next-generation superhard materials and catalysts.
Thermodynamic studies by Arblaster (2023) extended osmium’s thermal expansion and density equations to its melting point (~3400 K), confirming that osmium remains the densest element at all temperatures. Its corrosion resistance stems from the stability of the native OsO? layer, which forms only under strong oxidizing conditions and must be handled with care due to toxicity.
Applications and Advantages
Osmium is primarily used in alloys with iridium, platinum, and ruthenium to enhance hardness and wear resistance for electrical contacts, pen nibs, and high-pressure instrument pivots. It also serves as a key component in catalytic systems and as a reference material for ultra-high-pressure physics experiments. Os-based alloys and compounds such as OsB? and OsO? continue to drive research into superhard coatings, corrosion-resistant components, and catalytic oxidation processes.
Goodfellow Availability
Goodfellow provides osmium in high-purity form for research and industrial use. Available formats include small lumps, powders, and custom-machined components. Explore osmium and other platinum group metals through the Goodfellow product finder.
References
- Arblaster, J. W. (2023). Revised Crystallographic Properties of Osmium. Johnson Matthey Technology Review. https://doi.org/10.1595/205651323x16672247346816
- Dubrovinsky, L., et al. (2015). The most incompressible metal osmium at static pressures above 750 gigapascals. Nature, 525(7569), 226–229. https://doi.org/10.1038/nature14681
- Weinberger, M. B., Tolbert, S. H., & Kavner, A. (2008). Osmium metal studied under high pressure and nonhydrostatic stress. Physical Review Letters, 100(4), 045506. https://doi.org/10.1103/PhysRevLett.100.045506
- Chung, H.-Y., Yang, J.-M., Tolbert, S. H., & Kaner, R. B. (2008). Anisotropic mechanical properties of ultra-incompressible, hard osmium diboride. Journal of Materials Research, 23(6), 1797–1806. https://doi.org/10.1557/JMR.2008.0221
- Arblaster, J. W. (2013). Crystallographic Properties of Osmium. Platinum Metals Review, 57(3), 177–184. https://doi.org/10.1595/147106713x668541