Ruthenium is a chemical element with the symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals. Russian-born scientist of Baltic-German ancestry Karl Ernst Claus discovered the element in 1844 at Kazan State University and named ruthenium in honor of Russia (Ruthenia is the Latin name of Rus).
Ruthenium is usually found as a minor component of platinum ores; the annual production has risen from about 19 tonnes in 2009 to some 35.5 tonnes in 2017.Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for ruthenium is in platinum alloys and as a chemistry catalyst. A new application of ruthenium is as the capping layer for extreme ultraviolet photomasks. Ruthenium is generally found in ores with the other platinum group metals in the Ural Mountains and in North and South America.
Approximately 30.9 tonnes of ruthenium were consumed in 2016, 13.8 of them in electrical applications, 7.7 in catalysis, and 4.6 in electrochemistry.
Because it hardens platinum and palladium alloys, ruthenium is used in electrical contacts, where a thin film is sufficient to achieve the desired durability. With similar properties and lower cost than rhodium,electric contacts are a major use of ruthenium.The ruthenium plate is applied to the electrical contact and electrode base metal by electroplating or sputtering.
Ruthenium dioxide with lead and bismuth ruthenates are used in thick-film chip resistors.These two electronic applications account for 50% of the ruthenium consumption.
Ruthenium is seldom alloyed with metals outside the platinum group, where small quantities improve some properties. The added corrosion resistance in titanium alloys led to the development of a special alloy with 0.1% ruthenium.Ruthenium is also used in some advanced high-temperature single-crystal superalloys,with applications that include the turbines in jet engines.
Several nickel based superalloy compositions are described, such as EPM-102 (with 3% Ru), TMS-162 (with 6% Ru), TMS-138,and TMS-174,the latter two containing 6% rhenium.
Fountain pen nibs are frequently tipped with ruthenium alloy. From 1944 onward, the Parker 51 fountain pen was fitted with the "RU" nib, a 14K gold nib tipped with 96.2% ruthenium and 3.8% iridium.
Ruthenium is a component of mixed-metal oxide (MMO) anodes used for cathodic protection of underground and submerged structures, and for electrolytic cells for such processes as generating chlorine from salt water.
The fluorescence of some ruthenium complexes is quenched by oxygen, finding use in optode sensors for oxygen.Ruthenium red, [(NH3)5Ru-O-Ru(NH3)4-O-Ru(NH3)5]6+, is a biological stain used to stain polyanionic molecules such as pectin and nucleic acids for light microscopy and electron microscopy.
The beta-decaying isotope 106 of ruthenium is used in radiotherapy of eye tumors, mainly malignant melanomas of the uvea.Ruthenium-centered complexes are being researched for possible anticancer properties. Compared with platinum complexes, those of ruthenium show greater resistance to hydrolysis and more selective action on tumors.
Ruthenium tetroxide exposes latent fingerprints by reacting on contact with fatty oils or fats with sebaceous contaminants and producing brown/black ruthenium dioxide pigment.