Ruthenium

Not to be confused with rutherfordium.
technetium ← ruthenium → rhodium
Fe
↑
Ru
↓
Os
Appearance
silvery white metallic
General properties
Name, symbol, number ruthenium, Ru, 44
Pronunciation /ruːˈθiːniəm/
roo-THEE-nee-əm
Element category transition metal
Group, period, block 8, 5, d
Standard atomic weight 101.07g·mol−1
Electron configuration [Kr] 4d7 5s1
Electrons per shell 2, 8, 18, 15, 1 (Image)
Physical properties
Density (near r.t.) 12.45 g·cm−3
Liquid density at m.p. 10.65 g·cm−3
Melting point 2607 K, 2334 °C, 4233 °F
Boiling point 4423 K, 4150 °C, 7502 °F
Heat of fusion 38.59 kJ·mol−1
Heat of vaporization 591.6 kJ·mol−1
Specific heat capacity (25 °C) 24.06 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 2588 2811 3087 3424 3845 4388
Atomic properties
Oxidation states 8, 7, 6, 4, 3, 2, 1,[1], -2
(mildly acidic oxide)
Electronegativity 2.3 (Pauling scale)
Ionization energies 1st: 710.2 kJ·mol−1
2nd: 1620 kJ·mol−1
3rd: 2747 kJ·mol−1
Atomic radius 134 pm
Covalent radius 146±7 pm
Miscellanea
Crystal structure hexagonal
Magnetic ordering paramagnetic[2]
Electrical resistivity (0 °C) 71 nΩ·m
Thermal conductivity (300 K) 117 W·m−1·K−1
Thermal expansion (25 °C) 6.4 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 5970 m/s
Young's modulus 447 GPa
Shear modulus 173 GPa
Bulk modulus 220 GPa
Poisson ratio 0.30
Mohs hardness 6.5
Brinell hardness 2160 MPa
CAS registry number 7440-18-8
Most stable isotopes
Main article: Isotopes of ruthenium
iso NA half-life DM DE (MeV) DP
96Ru 5.52% 96Ru is stable with 52 neutrons
97Ru syn 2.9 d ε - 97Tc
γ 0.215, 0.324 -
98Ru 1.88% 98Ru is stable with 54 neutrons
99Ru 12.7% 99Ru is stable with 55 neutrons
100Ru 12.6% 100Ru is stable with 56 neutrons
101Ru 17.0% 101Ru is stable with 57 neutrons
102Ru 31.6% 102Ru is stable with 58 neutrons
103Ru syn 39.26 d β− 0.226 103Rh
γ 0.497 -
104Ru 18.7% 104Ru is stable with 60 neutrons
106Ru syn 373.59 d β− 3.54 106Rh

Ruthenium (pronounced /ruːˈθiːniəm/ roo-THEE-nee-əm) is the chemical element with the atomic number 44, and is represented by the symbol Ru. It is a rare transition metal of the platinum group of the periodic table; and like the other metals of the platinum group, ruthenium is inert to most other chemicals. The Russian scientist Karl Klaus discovered the element in 1844 and named it after Ruthenia, the Latin word for Rus'. Ruthenium is found associated with platinum ores. Ruthenium is a minor component in these ores and therefore is a relatively rare element. Most ruthenium is used for wear-resistant electrical contacts and the production of thick-film resistors. Another, minor application of ruthenium is its use in some platinum alloys.

Contents

Characteristics

Physical properties

An irregular bar of lustrous silvery metal. One end is rough, as though broken, while the other, cigar-shaped end is relatively smooth.
A half of a pure, electron-beam remelted ruthenium bar

A polyvalent hard white metal, ruthenium is a member of the platinum group, and is in group 8 of the periodic table:

Z Element No. of electrons/shell
26 iron 2, 8, 14, 2
44 ruthenium 2, 8, 18, 15, 1
76 osmium 2, 8, 18, 32, 14, 2
108 hassium 2, 8, 18, 32, 32, 14, 2

However, it has an atypical configuration in its outermost electron shells compared to the rest of the members: whereas all other group-8 elements have 2 electrons in the outermost shell, in ruthenium, one of those is transferred to a lower shell. (This can be observed in the neighborhood of niobium (41), ruthenium (44), rhodium (45), and palladium (46).)

Ruthenium has four crystal modifications and does not tarnish at normal temperatures, but does oxidize readily on exposure to air to form ruthenium tetroxide, RuO4, a strong oxidizing agent with properties analogous to those of osmium tetroxide. Ruthenium dissolves in fused alkalis, is not attacked by acids but is attacked by halogens at high temperatures. Small amounts of ruthenium can increase the hardness of platinum and palladium. The corrosion resistance of titanium is increased markedly by the addition of a small amount of ruthenium.[3]

This metal can be plated either by electroplating or by thermal decomposition methods. A ruthenium-molybdenum alloy is known to be superconductive at temperatures below 10.6 K.[3]

Chemical properties

A small amount of a slightly clumpy, vivid red powder
Tris(bipyridine)ruthenium(II)-chloride

The oxidation states of ruthenium range from +1 to +8, and −2 is known. Ruthenium compounds are often similar in properties to those of osmium and exhibit at least eight oxidation states, but the +2, +3, and +4 states are the most common. Examples are ruthenium(IV) oxide (RuO2, oxidation state +4), dipotassium ruthenate (K2RuO4, +6), potassium perruthenate (KRuO4, +7) and ruthenium tetroxide (RuO4, +8). Compounds of ruthenium with chlorine are ruthenium(II) chloride (RuCl2) and ruthenium(III) chloride (RuCl3).[4]

Organometallic chemistry

Ruthenium is a versatile metal that can easily form compounds with carbon-ruthenium bonds; these compounds tend to be darker in color and react more quickly than the osmium compounds. The organometallic ruthenium compound that is easiest to make is RuHCl(CO)(PPh3)3 (chlorohydrotris(triphenylphosphine)ruthenium (II)). This compound has two forms (yellow and pink) that are identical once they are dissolved but different in the solid state.[4]

An organometallic compound similar to ruthenocene, bis(2,4-dimethylpentadienyl)ruthenium, is readily synthesized in near quantitative yields and has applications in vapor-phase deposition of metallic ruthenium, as well as in catalysis, including Fischer-Tropsch synthesis of transportation fuels.[5] Important catalysts based on ruthenium are Grubbs' catalyst[6] and Roper's complex[7].

Isotopes

Naturally occurring ruthenium is composed of seven stable isotopes. Additionally, 34 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are 106Ru with a half-life of 373.59 days, 103Ru with a half-life of 39.26 days and 97Ru with a half-life of 2.9 days.[8][9]

Fifteen other radioisotopes have been characterized with atomic weights ranging from 89.93 u (90Ru) to 114.928 u (115Ru). Most of these have half-lives that are less than five minutes except 95Ru (half-life: 1.643 hours) and 105Ru (half-life: 4.44 hours).[8][9]

The primary decay mode before the most abundant isotope, 102Ru, is electron capture and the primary mode after is beta emission. The primary decay product before 102Ru is technetium and the primary mode after is rhodium.[8][9]

History

Though naturally occurring platinum, containing all six platinum group metals, was used for a long time by pre-Columbian Americans and known as a material to European chemists from the mid-16th century, it took until the mid-18th century for platinum to be identified as a pure element. The discovery that natural platinum contained palladium, rhodium, osmium and iridium took place in the first decade of the 19th century.[10] Platinum in alluvial sands of Russian rivers gave access to raw material for use in plates and medals and for the minting of ruble coins, starting in 1828.[11] Residues of platinum production for minting were available in the Russian Empire, and therefore most of the research on them was done in Eastern Europe.

It is possible that the Polish chemist Jędrzej Śniadecki isolated element 44 (which he called "vestium") from platinum ores in 1807. His work was never confirmed, however, and he later withdrew his claim of discovery.[12] Jöns Berzelius and Gottfried Osann nearly discovered ruthenium in 1827.[13] They examined residues that were left after dissolving crude platinum from the Ural Mountains in aqua regia. Berzelius did not find any unusual metals, but Osann thought he found three new metals, pluranium, ruthenium and polinium. This discrepancy led to a long-standing controversy between Berzelius and Osann about the composition of the residues.[14]

In 1844, the Russian scientist Karl Klaus showed that the compounds prepared by Gottfried Osann contained small amounts of ruthenium, which Klaus had discovered the same year.[10] Klaus isolated ruthenium from the platinum residues of the rouble production while he was working in Kazan University, Kazan.[14] Klaus showed that ruthenium oxide contained a new metal and obtained 6 grams of ruthenium from the part of crude platinum that is insoluble in aqua regia.[14]

The name derives from Ruthenia, the Latin word for Rus', a historical area which includes present-day western Russia, Ukraine, Belarus, and parts of Slovakia and Poland. Karl Klaus used the name proposed by Gottfried Osann in 1828. He chose the element's name in honor of his birthland, as he was born in Tartu, Estonia, which was at the time a part of the Russian Empire.[10][15]

Occurrence

Ruthenium is exceedingly rare and is the 74th most abundant metal on Earth.[12] This element is generally found in ores with the other platinum group metals in the Ural Mountains and in North and South America. Small but commercially important quantities are also found in pentlandite extracted from Sudbury, Ontario, Canada, and in pyroxenite deposits in South Africa. The native ruthenium is very rare mineral (Ir replaces part of Ru in its structure).[16][17]

Production

Mining

Roughly 12 tonnes of Ru is mined each year with world reserves estimated as 5,000 tonnes.[12] The composition of the mined platinum group metal (PGM) mixtures varies in a wide range depending on the geochemical formation. For example, the PGMs mined in South Africa contain on average 11% ruthenium while the PGMs mined in the USSR contain only 2% based on research dating from 1992.[18][19]

Ruthenium, like the other platinum group metals, is obtained commercially as a by-product from nickel and copper mining and processing or by direct processing of platinum group metal ores. During electrorefining of copper and nickel, noble metals such as silver, gold and the platinum group metals including selenium and tellurium settle to the bottom of the cell as anode mud, which forms the starting point for their extraction.[16][17] In order to separate the metals, they must first be brought into solution. Several methods are available depending on the separation process and the composition of the mixture; two representative methods are fusion with sodium peroxide followed by dissolution in aqua regia, and dissolution in a mixture of chlorine with hydrochloric acid.[20][21] Osmium, ruthenium, rhodium and iridium can be separated from platinum and gold and base metals by their insolubility in aqua regia, leaving a solid residue. Rhodium can be separated from the residue by treatment with molten sodium bisulfate. The insoluble residue, containing Ru, Os and Ir is treated with sodium oxide, in which Ir is insoluble, producing water-soluble Ru and Os salts. After oxidation to the volatile oxides, RuO4 is separated from OsO4 by precipitation of (NH4)3RuCl6 with ammonium chloride or by distillation or extraction with organic solvents of the volatile osmium tetroxide.[22] Hydrogen is used to reduce ammonium ruthenium chloride yielding a powder.[4] The first method to precipitate the ruthenium with ammonium chloride is similar to the procedure that Smithson Tennant and William Hyde Wollaston used for their separation. Several methods are suitable for industrial scale production. In either case, the product is reduced using hydrogen, yielding the metal as a powder or sponge that can be treated using powder metallurgy techniques or by argon-arc welding.[23]

From used nuclear fuels

Ruthenium is a fission product of uranium-235, therefore each kilo of fission products contains significant amounts of the lighter platinum group metals and therefore also ruthenium. Used nuclear fuel might be a possible source for ruthenium. The complicated extraction is expensive and the also present radioactive isotopes of ruthenium would make a storage for several half-lives of the decaying isotopes necessary. This makes this source of ruthenium unattractive and no large-scale extraction has been started.[24][25][26]

Applications

Because of its ability to harden platinum and palladium, ruthenium is used in platinum and palladium alloys to make wear-resistant electrical contacts. In this application, only thin plated films are used to achieve the necessary wear-resistance. Because of its lower cost and similar properties compared to rhodium,[23] the use as plating material for electric contacts is one of the major applications.[16][27] The thin coatings are either put on by electroplating[28] or sputtering.[29]

Ruthenium dioxide, lead and bismuth[30] ruthenates, the latter with perovskite crystal structure,[31] are used in thick film chip resistors.[32] The first two applications account for 50% of the ruthenium consumption.[12]

There are only a few alloys used other than with elements of the platinum group metals. Ruthenium is always used in small quantities in those alloys to improve certain properties of the alloys. One example is the use of small amounts of ruthenium to increase the stability of gold in jewelry. The beneficial effect on the corrosion resistance of titanium alloys led to the development of a special alloy containing 0.1% ruthenium .[33] Ruthenium is also used in some advanced high-temperature single-crystal superalloys, with applications including the turbine blades in jet engines. Several nickel based superalloy compositions are described in the literature. Among them are EPM-102 (with 3 % Ru) and TMS-162 (with 6 % Ru), both containing 6 % rhenium,[34] as well as TMS-138[35] and TMS-174.[36][37] Fountain pen nibs are frequently tipped with alloys containing ruthenium. From 1944 onward, the famous Parker 51 fountain pen was fitted with the "RU" nib, a 14K gold nib tipped with 96.2% ruthenium and 3.8% iridium.[38]

Ruthenium is a component of mixed-metal oxide (MMO) anodes used for cathodic protection of underground and submerged structures, and for electrolytic cells for chemical processes such as generating chlorine from salt water.[39] The fluorescence of some ruthenium complexes is quenched by oxygen, which has led to their use as optode sensors for oxygen.[40] 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.[41] The beta-decaying isotope 106 of ruthenium is used in radiotherapy of eye tumors, mainly malignant melanomas of the uvea.[42] Ruthenium-centered complexes are being researched for possible anticancer properties.[43] Ruthenium, unlike traditional platinum complexes, shows greater resistance to hydrolysis and more selective action on tumors. NAMI-A and KP1019 are two drugs undergoing clinical evaluation against metastatic tumors and colon cancers.

Laboratory uses

Ruthenium is also a versatile catalyst. Hydrogen sulfide can be split by light by using an aqueous suspension of CdS particles loaded with ruthenium dioxide. This may be useful in the removal of H2S from oil refineries and from other industrial processes.[44] Organometallic ruthenium carbene and allenylidene complexes have recently been found as highly efficient catalysts for olefin metathesis with important applications in organic and pharmaceutical chemistry.[45] Some ruthenium complexes absorb light throughout the visible spectrum and are being actively researched in various, potential, solar energy technologies. Ruthenium-based compounds have been used for light absorption in dye-sensitized solar cells, a promising new low-cost solar cell system.[46] Ruthenium chemical vapor deposition (CVD) is used as a method to produce thin films of pure ruthenium on substrates. These films show promising properties for the use in microchips and for the giant magnetoresistive read element for hard disk drives.[47] Ruthenium was also suggested as a possible material for microelectronics because its use is compatible with semiconductor processing techniques.[48]

Precautions

The compound ruthenium tetroxide, RuO4, similar to osmium tetroxide, is volatile, highly toxic and may cause explosions if allowed to come into contact with combustible materials.[49] Ruthenium plays no biological role but does strongly stain human skin, may be carcinogenic[50] and bio-accumulates in bone.

References

  1. ↑ "Ruthenium: ruthenium(I) fluoride compound data". OpenMOPAC.net. http://openmopac.net/data_normal/ruthenium(i)%20fluoride_jmol.html. Retrieved 2007-12-10. 
  2. ↑ Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
  3. ↑ 3.0 3.1 Hamond, C.R. "The elements", in Lide, D. R., ed. (2005), CRC Handbook of Chemistry and Physics (86th ed.), Boca Raton (FL): CRC Press, ISBN 0-8493-0486-5 
  4. ↑ 4.0 4.1 4.2 Cotton, Simon (1997). Chemistry of Precious Metals. Springer-Verlag New York, LLC. pp. 1–20. ISBN 0751404136. http://books.google.com/?id=6VKAs6iLmwcC&pg=PA2. 
  5. ↑ Murahashi, Shun-Ichi, ed (2004). "Ruthenium Catalyzed Fischer-Tropsch synthesis". Ruthenium in organic synthesis. Weinheim: Wiley. pp. 278–279. ISBN 9783527306923. http://books.google.com/?id=NkTY1gHEqYwC&pg=PA278. 
  6. ↑ Bruneau, C., ed (2004). "Self-Metathesis and Cross-Metathesis of Unsaturated Organosilicon Derivates". Ruthenium catalysts and fine chemistry. Berlin: Springer. pp. 213–214. ISBN 9783540205432. 
  7. ↑ Sentets, Stephane; Rodriguez Martinez, Maria del Carmen; Vendier, Laure; Donnadieu, Bruno; Huc, Vincent; Lugan, Noël; Lavigne, Guy (2005). "Instant “Base-Promoted” Generation of Roper's-type Ru(0) Complexes Ru(CO)2(PR3)3from a Simple Carbonylchlororuthenium(II) Precursor". Journal of the American Chemical Society 127 (42): 14554. doi:10.1021/ja055066e. PMID 16231891. 
  8. ↑ 8.0 8.1 8.2 Lide, D. R., ed. (2005), CRC Handbook of Chemistry and Physics (86th ed.), Boca Raton (FL): CRC Press, ISBN 0-8493-0486-5  Section 11, Table of the Isotopes
  9. ↑ 9.0 9.1 9.2 Audi, G. et al. (2003). "The Nubase evaluation of nuclear and decay properties". Nuclear Physics A 729: 3. doi:10.1016/j.nuclphysa.2003.11.001. http://amdc.in2p3.fr/web/nubase_en.html. 
  10. ↑ 10.0 10.1 10.2 Weeks, Mary Elvira (1932). "The discovery of the elements. VIII. The platinum metals". Journal of Chemical Education 9: 1017. doi:10.1021/ed009p1017. 
  11. ↑ Raub, Christoph J. (2004). The Minting of Platinum Roubles. Part I: History and Current Investigations. 48. pp. 66–69. http://www.platinummetalsreview.com/dynamic/article/view/48-2-066-069. 
  12. ↑ 12.0 12.1 12.2 12.3 Emsley, J. (2003). "Ruthenium". Nature's Building Blocks: An A-Z Guide to the Elements. Oxford, England, UK: Oxford University Press. pp. 368–370. ISBN 0198503407. 
  13. ↑ "New Metals in the Uralian Platina". The Philosophical Magazine 2: 391–392. 1827. http://books.google.com/?id=x57C3yhRPUAC&pg=PA391. 
  14. ↑ 14.0 14.1 14.2 Pitchkov, V. N. (1996). "The Discovery of Ruthenium". Platinum Metals Review 40 (4): 181–188. http://www.platinummetalsreview.com/dynamic/article/view/pmr-v40-i4-181-188. 
  15. ↑ Partington, James Riddick (1964). History of Chemistry. 4. London: Macmillan & Co. p. 499. 
  16. ↑ 16.0 16.1 16.2 George, Micheal W.. "2006 Minerals Yearbook: Platinum-Group Metals". United States Geological Survey USGS. http://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2006-plati.pdf. Retrieved 2008-09-16. 
  17. ↑ 17.0 17.1 "Commodity Report: Platinum-Group Metals". United States Geological Survey USGS. http://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2008-plati.pdf. Retrieved 2008-09-16. 
  18. ↑ Hartman, H. L.; Britton, S. G., ed (1992). SME mining engineering handbook. Littleton, Colo.: Society for Mining, Metallurgy, and Exploration. p. 69. ISBN 9780873351003. http://books.google.com/?id=Wm6QMRaX9C4C&pg=PA69. 
  19. ↑ Harris, Donald C.; Cabri, L. J. (1973). "The nomenclature of the natural alloys of osmium, iridium and ruthenium based on new compositional data of alloys from world-wide occurrences". The Canadian Mineralogist 12 (2): 104–112. http://canmin.geoscienceworld.org/cgi/content/abstract/12/2/104. 
  20. ↑ Renner, H.; Schlamp, G.; Kleinwächter, I.; Drost, E.; Lüschow, H. M.; Tews, P.; Panster, P.; Diehl, M.; Lang, J.; Kreuzer, T.; Knödler, A.; Starz, K. A.; Dermann, K.; Rothaut, J.; Drieselman, R. (2002). "Platinum group metals and compounds". Ullmann's Encyclopedia of Industrial Chemistry. Wiley. doi:10.1002/14356007.a21_075. 
  21. ↑ Seymour, R. J.; O'Farrelly, J. I. (2001). "Platinum-group metals". Kirk Othmer Encyclopedia of Chemical Technology. Wiley. doi:10.1002/0471238961.1612012019052513.a01.pub2. 
  22. ↑ Gilchrist, Raleigh (1943). "The Platinum Metals.". Chemical Reviews 32 (3): 277–372. doi:10.1021/cr60103a002. 
  23. ↑ 23.0 23.1 Hunt, L. B.; Lever, F. M. (1969). "Platinum Metals: A Survey of Productive Resources to industrial Uses". Platinum Metals Review 13 (4): 126–138. http://www.platinummetalsreview.com/pdf/pmr-v13-i4-126-138.pdf. 
  24. ↑ Kolarik, Zdenek; Renard, Edouard V. (2005). "Potential Applications of Fission Platinoids in Industry". Platinum Metals Review 49: 79. doi:10.1595/147106705X35263. http://www.platinummetalsreview.com/pdf/79-90-pmr-apr05.pdf. 
  25. ↑ Kolarik, Zdenek; Renard, Edouard V. (2003). "Recovery of Value Fission Platinoids from Spent Nuclear Fuel. Part I PART I: General Considerations and Basic Chemistry". Platinum Metals Review 47 (2): 74–87. http://www.platinummetalsreview.com/pdf/pmr-v47-i2-074-087.pdf. 
  26. ↑ Kolarik, Zdenek; Renard, Edouard V. (2003). "Recovery of Value Fission Platinoids from Spent Nuclear Fuel. Part II: Separation Process". Platinum Metals Review 47 (2): 123–131. http://www.platinummetalsreview.com/pdf/pmr-v47-i2-074-087.pdf. 
  27. ↑ Rao, C; Trivedi, D (2005). "Chemical and electrochemical depositions of platinum group metals and their applications". Coordination Chemistry Reviews 249: 613. doi:10.1016/j.ccr.2004.08.015. 
  28. ↑ Weisberg, A (1999). "Ruthenium plating". Metal Finishing 97: 297. doi:10.1016/S0026-0576(00)83089-5. 
  29. ↑ prepared under the direction of the ASM International Handbook Committee ; Merrill L. Minges, technical chairman. (1989). Electronic materials handbook. Materials Park, OH: ASM International. p. 184. ISBN 9780871702852. http://books.google.com/?id=EkStW7v8VPkC&pg=RA3-PA550. 
  30. ↑ Busana, M. G.; Prudenziati, M.; Hormadaly, J. (2006). "Microstructure development and electrical properties of RuO2-based lead-free thick film resistors". Journal of Materials Science Materials in Electronics 17: 951. doi:10.1007/s10854-006-0036-x. 
  31. ↑ Rane, Sunit; Prudenziati, Maria; Morten, Bruno (2007). "Environment friendly perovskite ruthenate based thick film resistors". Materials Letters 61: 595. doi:10.1016/j.matlet.2006.05.015. 
  32. ↑ Slade, Paul G., ed (1999). Electrical contacts : principles and applications. New York, NY: Dekker. p. 550. ISBN 9780824719340. http://books.google.com/?id=c2YxCCaM9RIC&pg=PA184. 
  33. ↑ Schutz, R. W. (1996). "Ruthenium Enhanced Titanium Alloys". Platinum Metals Review 40 (2): 54–61. http://www.platinummetalsreview.com/pdf/pmr-v40-i2-054-061.pdf. 
  34. ↑ Bondarenko, Yu. A.; Kablov, E. N.; Surova, V. A.; Echin, A. B. (2006). "Effect of high-gradient directed crystallization on the structure and properties of rhenium-bearing single-crystal alloy". Metal Science and Heat Treatment 48: 360. doi:10.1007/s11041-006-0099-6. 
  35. ↑ "Fourth generation nickel base single crystal superalloy". http://sakimori.nims.go.jp/catalog/TMS-138-A.pdf. 
  36. ↑ Koizumi, Yutaka et al.. "Development of a Next-Generation Ni-base Single Crystal Superalloy". Proceedings of the International Gas Turbine Congress, Tokyo November 2–7, 2003. http://nippon.zaidan.info/seikabutsu/2003/00916/pdf/igtc2003tokyo_ts119.pdf. 
  37. ↑ Walston, S.; Cetel, A.; MacKay, R.; O'Hara, K.; Duhl, D.; Dreshfield, R.. "Joint Development of a Fourth Generation Single Crystal Superalloy". http://gltrs.grc.nasa.gov/reports/2004/TM-2004-213062.pdf. 
  38. ↑ Mottishaw, J. (1999). "Notes from the Nib Works—Where's the Iridium?". The PENnant XIII (2). http://www.nibs.com/ArticleIndex.html. 
  39. ↑ Cardarelli, François (2008). "Dimensionally Stable Anodes (DSA®) for Chlorine Evolution". Materials Handbook: A Concise Desktop Reference. London: Springer. pp. 581–582. ISBN 9781846286681. http://books.google.com/?id=ArsfQZig_9AC&pg=PT612. 
  40. ↑ Varney, Mark S. (2000). "Oxygen Microoptode". Chemical sensors in oceanography. Amsterdam: Gordon & Breach. pp. 150. ISBN 9789056992552. 
  41. ↑ Hayat, M. A. (1993). "Ruthenium red". Stains and cytochemical methods. New York, NY: Plenum Press. pp. 305–310. ISBN 9780306442940. http://books.google.com/?id=oGj7MLioFlQC&pg=PA305. 
  42. ↑ Wiegel, T. (1997). Radiotherapy of ocular disease, Ausgabe 13020. Basel ;Freiburg: Karger. ISBN 9783805563925. http://books.google.com/?id=Aa83RoXCNk0C&pg=PA97. 
  43. ↑ Richards, AD; Rodger, A; Rodger, A. (2007). "Synthetic metallomolecules as agents for the control of DNA structure". Chem. Soc. Rev. 36 (3): 471–483. doi:10.1039/b609495c. PMID 17325786. http://www.rsc.org/publishing/journals/CS/article.asp?doi=b609495c. 
  44. ↑ Atak, Suna; C̦elik, Mehmet Sabri (1998). Innovations in Mineral and Coal Processing. Taylor & Francis. p. 498. ISBN 9789058090133. http://books.google.com/?id=fI8Yo0bX7BwC&pg=PA498. 
  45. ↑ Fürstner, Alois (2000). "Olefin Metathesis and Beyond". Angewandte Chemie International Edition 39: 3012. doi:10.1002/1521-3773(20000901)39:17<3012::AID-ANIE3012>3.0.CO;2-G. 
  46. ↑ Kuang, Daibin; Ito, Seigo; Wenger, Bernard; Klein, Cedric; Moser, Jacques-E; Humphry-Baker, Robin; Zakeeruddin, Shaik M.; Grätzel, Michael (2006). "High Molar Extinction Coefficient Heteroleptic Ruthenium Complexes for Thin Film Dye-Sensitized Solar Cells". Journal of the American Chemical Society 128 (12): 4146. doi:10.1021/ja058540p. PMID 16551124. 
  47. ↑ Kar, Samares (2007-09). Physics and Technology of High-k Gate Dielectrics 5, Ausgabe 4. The Electrochemical Society. p. 569. ISBN 20079781566775700. http://books.google.com/?id=5YYIlaownVMC&pg=PA569. 
  48. ↑ Cheng, A. H.-B.; Daniels, M.; Luttmer, J. D. (1998). "Etching Byproducts of Ruthenium Wafers Using Various Etching Chemistries". Environmental issues in the electronics/semiconductor industries and: Electrochemical/photochemical methods for pollution. The Electrochemical Society. pp. 10–14. ISBN 9781566771993. 
  49. ↑ Tojo, G. and Fernández, M. (2007). "Ruthenium Tetroxide and Other Ruthenium Compounds". Oxidation of Primary Alcohols to Carboxylic Acids. New York: Springer. pp. 61–78. doi:10.1007/0-387-35432-8. ISBN 978-0-387-35431-6. 
  50. ↑ Inhalation of radionuclides and carcinogenesis

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Li Be   B C N O F Ne
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Rb Sr   Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Uuq Uup Uuh Uus Uuo
Alkali metals Alkaline earth metals Lanthanides Actinides Transition metals Other metals Metalloids Other nonmetals Halogens Noble gases
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