Scandium

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properties
General
Name , symbol , atomic number Scandium, Sc, 21
Element category Transition metals
Group , period , block 3 , 4 , d
Appearance silvery white
CAS number 7440-20-2
EC number 231-129-2
ECHA InfoCard 100.028.299
Mass fraction of the earth's envelope 5.1  ppm
Atomic
Atomic mass 44.955908 (5) et al
Atomic radius (calculated) 160 (184) pm
Covalent radius 170 pm
Electron configuration [ Ar ] 3 d 1 4 s 2
1. Ionization energy 6th.56149 (6) eV ≈ 633.09 kJ / mol
2. Ionization energy 12.79977 (25) eV ≈ 1 234.99 kJ / mol
3. Ionization energy 24.756 838 (12) eV ≈ 2 388.67 kJ / mol
4. Ionization energy 73.4894 (4) eV ≈ 7 090.6 kJ / mol
5. Ionization energy 91.95 (3) eV ≈ 8 870 kJ / mol
Physically
Physical state firmly
Crystal structure hexagonal
density 2.985 g / cm 3
Mohs hardness 2.5
magnetism paramagnetic ( Χ m = 2.6 10 −4 )
Melting point 1814 K (1541 ° C)
boiling point 3003 K (2730 ° C)
Molar volume 15.00 10 −6 m 3 mol −1
Heat of evaporation 310 kJ / mol
Heat of fusion 16 kJ mol −1
Specific heat capacity 586 J kg −1 K −1
Electric conductivity 1.81 · 10 6 A · V −1 · m −1
Thermal conductivity 16 W m −1 K −1
Chemically
Oxidation states 3
Normal potential −2.03 V (Sc 3+ + 3 e - → Sc)
Electronegativity 1.36 ( Pauling scale )
Isotopes
isotope NH t 1/2 ZA ZE (M eV ) ZP
43 Sc {syn.} 3.891 h ε 2.221 43 Approx
44 Sc {syn.} 3,927 h ε 3.653 44 Approx
45 Sc 100  % Stable
46 Sc {syn.} 83.79 d β - 2.367 46 Ti
47 Sc {syn.} 3.3492 d β - 0.600 47 Ti
48 Sc {syn.} 43.67 h β - 3,994 48 Ti
49 Sc {syn.} 57.2 min β - 2.006 49 Ti
For other isotopes see list of isotopes
NMR properties
  Spin
quantum
number I 		γ in
rad · T −1 · s −1 		E r  ( 1 H) f L at
B = 4.7 T
in MHz
45 Sc 7/2 0+6.508 10 7 0.302 048.69
safety instructions
GHS labeling of hazardous substances

powder

02 - Highly / extremely flammable

danger

H and P phrases H: 228
P: 210
As far as possible and customary, SI units are used.
Unless otherwise noted, the data given apply to standard conditions .

Scandium (from Latin Scandia "Scandinavia") is a chemical element with the symbol Sc and the atomic number 21. In the periodic table it is in the 3rd subgroup , or the 3rd  IUPAC group or Scandium group . The silver-white element, which is soft at room temperature, is the first of the transition metals and is also classified as a rare earth metal .

history

Scandium was discovered by Lars Fredrik Nilson in 1879 . From 10 kg of euxenite and gadolinite , he isolated an oxide with previously unknown properties. He named the new element he suspected "Scandium" in honor of his homeland. As early as 1869, Dmitri Ivanovich Mendeleev predicted an element of Eka- Bor. Only Per Teodor Cleve later recognized the correspondence of the scandium with the eka-boron.

Pure scandium was in 1937 electrolytically from a eutectic melt of sodium, potassium, lithium and scandium at 700 to 800  ° C produced.

In 2003 there were only three mine production sites worldwide: Bayan Obo Mine (People's Republic of China), Shovti Vody (Ukraine) and on the Kola Peninsula (Russia).

In 2018 a production facility in Australia was added by Australian Mines.

Occurrence

Scandium is one of the rare elements. It does not occur elementally, it is only found in enriched form in a few rare minerals . Scandium as the main component contain only five minerals:

In addition, so far (as of 2013) 14 other minerals are known in which scandium are represented in smaller proportions in the chemical formula such as, but Jervisit , Bazzit , Juonniit , Cascandit , Davisit and Scandiobabingtonit .

As an admixture in low concentrations, scandium is found in a few hundred minerals, with some sources specifying more than 800 minerals. It is therefore also contained in ore concentrates of the transition metals as an “impurity”. These include Russian and Chinese wolframite and tantalite concentrates . Scandium compounds are also produced when processing ores containing uranium . Mines are located in Shovti Vody in Ukraine , among others .

Extraction and manufacture

The main starting material is thortveitite, which is processed into scandium oxide in several process steps . Metallic scandium is then produced by converting it to fluoride and reducing it with calcium .

According to the USGS , annual production is estimated at 10 to 15 tons.

properties

pure scandium, sublimated-dendritic

Due to its density, scandium is one of the light metals. In air it becomes dull, a protective yellowish oxide layer is formed. Scandium reacts with dilute acids to form hydrogen and trivalent cations . In water vapor the reaction to form scandium oxide Sc takes place from 600 ° C 2 O 3 . In aqueous solutions, Sc cations behave similarly to aluminum, which often causes difficulties in analytical separations. In a mixture of nitric acid and 48% hydrogen fluoride , it should be resistant.

use

Scandium is mainly used as scandium iodide in high-performance, high-pressure mercury vapor lamps , for example for stadium lighting. Together with holmium and dysprosium , a light similar to daylight is created. Scandium is also used to make laser crystals. Scandium oxide is added to magnetic data storage media to increase the rate of magnetization reversal. Scandium as scandium chloride is used in microscopic amounts as an important component in the catalyst in the production of hydrogen chloride ; researchers at the Max Planck Institute for Carbon Research also used it to produce a catalyst for loading and unloading metal hydride storage media for hydrogen , which in addition to the scandium chloride ScCl 3 among other things still contained sodium hydride and aluminum . However, titanium-containing catalysts were later used.

As an alloy additive , scandium shows structure-stabilizing and grain-size-reducing effects. An aluminum-lithium alloy with a small amount of scandium is used to manufacture some components in Russian fighter planes. Scandium alloys are also used in the modern bicycle industry (see racing bike ). These alloys also contain relatively little scandium. At the end of the 1990s, the revolver manufacturer Smith & Wesson released the revolver model 360PD. The frame, made of a scandium-aluminum alloy, enables a significant weight reduction.

Great expectations are attached to the use of aluminum scandium nitride as a semiconductor material for power electronic components . The research on this is currently (as of 2020) at an early stage, but the first progress has been made in the development of industrial-grade epitaxy processes . Research also focuses on the piezoelectric and pyroelectric properties , and in particular the ferroelectric properties of the material, which were only discovered in 2019 and which open up numerous other fields of application.

safety instructions

Scandium powder is flammable and therefore classified as flammable. It can easily be ignited by brief exposure to an ignition source and continues to burn after its removal. The more finely the substance is distributed, the greater the risk of ignition.

links

Web links

Commons : Scandium  - collection of images, videos and audio files
Wiktionary: Scandium  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ a b Harry H. Binder: Lexicon of the chemical elements. S. Hirzel Verlag, Stuttgart 1999, ISBN 3-7776-0736-3 .
  2. ↑ The values ​​for the properties (info box) are taken from www.webelements.com (Scandium) , unless otherwise stated .
  3. ↑ CIAAW, Standard Atomic Weights Revised 2013 .
  4. ↑ a b c d e Entry on scandium in Kramida, A., Ralchenko, Yu., Reader, J. and NIST ASD Team (2019): NIST Atomic Spectra Database (ver. 5.7.1) . Ed .: NIST , Gaithersburg, MD. doi : 10.18434 / T4W30F ( https://physics.nist.gov/asd ). Retrieved June 11, 2020.
  5. ↑ a b c d e Entry on scandium at WebElements, https://www.webelements.com , accessed on June 11, 2020.
  6. ↑ Robert C. Weast (Ed.): CRC Handbook of Chemistry and Physics . CRC (Chemical Rubber Publishing Company), Boca Raton 1990, ISBN 0-8493-0470-9 , pp. E-129 to E-145. Values ​​there are based on g / mol and given in cgs units. The value specified here is the SI value calculated from it, without a unit of measure.
  7. ↑ a b Yiming Zhang, Julian RG Evans, Shoufeng Yang: Corrected Values ​​for Boiling Points and Enthalpies of Vaporization of Elements in Handbooks. In: Journal of Chemical & Engineering Data. 56, 2011, pp. 328-337, doi: 10.1021 / je1011086 .
  8. ↑ a b c Entry on scandium in the GESTIS substance database of the IFA , accessed on April 30, 2017(JavaScript required) .
  9. ↑ mineralinfo.org: Les enjeux du Scandium dans la filière superalliages ( Memento of March 24, 2012 in the Internet Archive ).
  10. ^ Scandium Oxide - Australian Mines Limited. Retrieved February 5, 2019 .
  11. ↑ Michael Fleischer, Joseph A. Mandarino: Glossary of Mineral Specimens 1991. The Mineragical Record Inc., Tucson.
  12. ↑ a b Webmineral - Mineral Species containing Scandium .
  13. ^ IMA / CNMNC List of Mineral Names; August 2013 (PDF 1.3 MB).
  14. ^ CT Horovitz: Scandium Its Occurrence, Chemistry Physics, Metallurgy, Biology and Technology . Elsevier, 2012, ISBN 978-0-323-14451-3 , pp. 50 ( limited preview in Google Book search).
  15. ↑ David R. Lide: CRC Handbook of Chemistry and Physics: A Ready-reference Book of Chemical ... CRC Press, 1993, ISBN 0-8493-0595-0 , pp. 4–27 ( limited preview in Google Book search).
  16. ↑ HA Das, J. Zonderhuis, HW Marel: scandium in rocks, minerals and sediments and its relations to iron and aluminum. In: Contributions to Mineralogy and Petrology. 32, 1971, pp. 231-244, doi: 10.1007 / BF00643336 .
  17. ↑ US Geological Survey: Mineral Commodity Summaries - Scandium, February 2014 , accessed May 12, 2014.
  18. ↑ MINERAL COMMODITY SUMMARIES 2015. (PDF 2.3 MB, p. 144 (141)) USGS , accessed on September 5, 2015 (English).
  19. ^ Ferdi Schüth, Michael Felderhoff, Borislov Bogdanovic; Max Planck Institute for Coal Research: Complex hydrides as materials for hydrogen storage. Accessed January 8, 2015.
  20. ↑ Note: Scandium aluminum nitride is also used
  21. ↑ Heinz Arnold in Markt & Technik January 21, 2019: New material better than GaN
  22. ↑ Ralf Higgelke in Markt & Technik October 23, 2019: Aluminum scandium nitride produced for the first time using MOCVD
  23. ↑ Nicolas Kurz: Investigation of the electro-acoustic and pyroelectric properties of aluminum-scandium-nitride for micro-acoustic high-frequency filters
  24. ↑ Julia Siekmann; Christian-Albrechts-Universität zu Kiel 10/17/2019 Newly discovered material property promises innovation in microelectronics