Osmium electrical resistivity

Osmium yields alloys with platinum characterised by hardness and tensile strength. They are very resistant to acid attack, and offer high electrical resistance. The alloys usually contain from 1 up to 10 per cent, of osmium.7... 

Table 3.1-271 [1.216] gives the specific electric resistivity of Os at different temperatures. The increase of atomic resistivity is shown in Table 3.1-263. Osmium coatings on W-based dispenser cathodes lower its work function (source Ba—Ca aluminate). It enhances the secondary electron emission (Fig. 3.1-344) and enables the operation at higher current densities in high power klystron and magnetron valves. Osmium shows superconductivity below 0.71 K and Table 3.1-272 gives some examples of superconducting Os alloys [1.218].

Copper is another transition metal that does not corrode easily, which makes it useful for water pipes. Copper is also an excellent conductor of heat, which explains why copper-bottomed cooking pans have been used for centuries. Today, most copper is used in electrical wiring, since it conducts electricity so well and can be stretched into thin shapes. Other transition metals that resist corrosion include platinum, osmium, and iridium. These last two elements are often used in metal pen nibs (the tip of a fountain ink pen) and the tip of spark plugs for cars. 

Osmium and Osmium Alloys Applications. Osmium is used as a component in hard, wear- and corrosion-resistant alloys, as surface coatings of W-based filaments of electric bulbs, cathodes of electron tubes, and thermo-ionic sources. Osmium itself. Os alloys, and Os compounds are strong and selective oxidation catalysts. Commercial grades available are powder in 99.6% and 99.95% purity, OSO4, and chemical compounds. 

Rhodium alloys find most of their applications in electrical contacts for radio frequency circuits, precision potentiometers, and spark plug electrodes. The trend is toward lower usage in electronics, mainly because of price. Osmium has minor uses in electrical equipment, mainly in contacts. Ruthenium is used in electrical contacts and high-voltage relays up to 500°C because even RuO c is conductive. A ruthenate thick-film paste is used for printed circuit resistance elements. The ruthenate is converted to RuOa, which has very low resistance drift, 0.10%. 

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