Ruthenium was initially discovered in 1808 by J.A. Sniadecki at the University of Vilno, Poland and then again by G.W. Osnann in 1828 at the University of Tartu, Russia.
Abundance and Extraction
Ruthenium is a rare member of the platinum group of metals (abundance 0.001 ppm in the earth’s crust). It is a lustrous, silvery coloured metal which is unaffected by air, water and acids, but is soluble in fused alkalis. Extraction of Ruthenium is achieved by several techniques; for example, extraction of the mixed platinum group metals by dissolution in aqua regia, followed by treatment of the various soluble and insoluble fractions.
Applications
Applications of Ruthenium are limited; as a pure metal, ruthenium is extremely hard and brittle and, consequently, difficult to machine.
It is relatively unreactive, and is used as an alloying element with platinum and palladium to produce alloys which have improved wear resistance, and with titanium to improve the material’s corrosion resistance.
In all cases, the Ruthenium addition has to be less than 15%, otherwise the resultant alloy is too hard to work.
Key Properties
The key properties of Ruthenium are tabulated below.
Table 1. Key properties
| Atomic Properties | |||
|---|---|---|---|
| Atomic number | 44 | ||
| Atomic radius – Goldschmidt ( nm ) | 0.134 | ||
| Atomic weight ( amu ) | 101.07 | ||
| Crystal structure | Hexagonal close packed | ||
| Electronic structure | Kr 4d7 5s1 | ||
| Photo-electric work function ( eV ) | 4.71 | ||
| Thermal neutron absorption cross-section ( Barns ) | 3.0 | ||
| Valences shown | 0, 1, 2, 3, 4, 5, 6, 7, 8 | ||
| Ionisation potential | No. | eV | |
| 1 | 7.36 | ||
| 2 | 16.8 | ||
| 3 | 28.5 | ||
| Natural isotope distribution | Mass No. | % | |
| 96 | 5.5 | ||
| 98 | 1.9 | ||
| 99 | 12.7 | ||
| 100 | 12.6 | ||
| 101 | 17.1 | ||
| 102 | 31.6 | ||
| 104 | 18.6 | ||
| Electrical Properties | |||
| Electrical resistivity @ 20 C ( µOhmcm ) | 7.7 | ||
| Temperature coefficient @ 0-100 C ( K-1 ) | 0.0041 | ||
| Superconductivity critical temperature ( K ) | 0.49 | ||
| Mechanical Properties | |||
| Material condition | Soft | Hard | Polycrystalline |
| Bulk modulus ( GPa ) | 286 | ||
| Hardness – Vickers | 350 | 750 | |
| Poisson’s ratio | 0.25 | ||
| Tensile modulus ( GPa ) | 432 | ||
| Tensile strength ( MPa ) | 495 | ||
| Yield strength ( MPa ) | 372 | ||
| Physical Properties | |||
| Boiling point ( C ) | 3900 | ||
| Density @ 20 C ( g cm-3 ) | 12.2 | ||
| Melting point ( C ) | 2310 | ||
| Thermal Properties | |||
| Coefficient of thermal expansion @ 0-100 C ( x10-6 K-1 ) | 9.6 | ||
| Latent heat of evaporation ( J g-1 ) | 5610 | ||
| Latent heat of fusion ( J g-1 ) | 252 | ||
| Specific heat @ 25 C ( J K-1 kg-1 ) | 238 | ||
| Thermal conductivity @ 0-100 C ( W m-1 K-1 ) | 117 | ||
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