Dysprosium


from Wikipedia, the free encyclopedia
properties
General
Name , symbol , atomic number Dysprosium, Dy, 66
Element category Lanthanoids
Group , period , block La , 6 , f
Appearance silvery white
CAS number 7429-91-6
EC number 231-073-9
ECHA InfoCard 100.028.249
Mass fraction of the earth's envelope 4.3 ppm
Atomic
Atomic mass 162,500 (1) u
Atomic radius (calculated) 175 (228) pm
Covalent radius 192 pm
Electron configuration [ Xe ] 4 f 10 6 s 2
1. Ionization energy 5.93905 (7) eV573.03 kJ / mol
2. Ionization energy 11.647 (20) eV1 123.8 kJ / mol
3. Ionization energy 22nd.89 (3) eV2 210 kJ / mol
4. Ionization energy 41.23 (8) eV3 980 kJ / mol
5. Ionization energy 62.1 (3) eV5 990 kJ / mol
Physically
Physical state firmly
Crystal structure hexagonal
density 8.559 g / cm 3 (25  ° C )
magnetism paramagnetic ( Χ m = 0.065)
Melting point 1680 K (1407 ° C)
boiling point 2873 K (2600 ° C)
Molar volume 19.01 · 10 −6 m 3 · mol −1
Heat of evaporation 280 kJ / mol
Heat of fusion 11.06 kJ mol −1
Speed ​​of sound 2710 m s −1 at 293.15 K.
Electric conductivity 1.08 · 10 6 A · V −1 · m −1
Thermal conductivity 11 W m −1 K −1
Chemically
Oxidation states 3
Normal potential −2.29 V (Dy 3+ + 3 e - → Dy)
Electronegativity 1.22 ( Pauling scale )
Isotopes
isotope NH t 1/2 ZA ZE (M eV ) ZP
154 Dy {syn.} 3 · 10 6 a α 2.947 150 Gd
155 Dy {syn.} 9.9 h ε 2.095 155 p
156 Dy 0.06% Stable
157 Dy {syn.} 8.14 h ε 1.341 157 p
158 Dy 0.10% Stable
159 Dy {syn.} 144.4 d ε 0.366 159 p
160 Dy 2.34% Stable
161 Dy 18.91% Stable
162 Dy 25.51% Stable
163 Dy 24.90% Stable
164 Dy 28.18% Stable
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
161 Dy 5/2 −0.92 · 10 7 3.44
163 Dy 5/2 1.289 · 10 7 4.82
safety instructions
GHS labeling of hazardous substances

powder

02 - Highly / extremely flammable

Caution

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 .

Dysprosium (from the Greek δυσπρόσιτος "inaccessible") is a chemical element with the element symbol Dy and the atomic number 66. In the periodic table it is in the group of lanthanoids and is therefore also one of the rare earth metals .

history

Dysprosium

In 1886, the Frenchman Paul Émile Lecoq de Boisbaudran succeeded in isolating dysprosium (III) oxide from a sample of holmium oxide , which until then had been considered a single substance. Since the chemical properties of the lanthanides are very similar and they are always associated in nature, a distinction was only possible here with very complex analysis methods. Its share in the structure of the earth's crust is given as 0.00042 percent by weight. The starting minerals are monazite and bastnasite .

Extraction and presentation

After a laborious separation of the other dysprosium companions, the oxide is converted to dysprosium fluoride with hydrogen fluoride . This is then reduced to metallic dysprosium with calcium to form calcium fluoride . Remaining calcium residues and other impurities are separated off in an additional remelting process in a vacuum . High-purity dysprosium is obtained after distillation in a high vacuum.

properties

Dysprosium is a silver-gray heavy metal that can be bent and stretched. Of the rare earth metal two modifications exist: At 1384 ° C, α-dysprosium (converts hexagonal most densely ) in β-dysprosium ( body-centered cubic ) in order.

The metal is very ignoble and therefore very reactive. In the air it becomes coated with an oxide layer, in water it is slowly attacked with formation of hydroxides, in dilute acids it is dissolved to form salts with formation of hydrogen.

Dysprosium has together with Holmium the highest magnetic moment (10.6 μ B ) of all chemical elements naturally occurring.

use

The economic and technical importance of dysprosium are relatively minor. Its output is estimated to be less than 100 tons per year. It is used in various alloys, in special magnets and alloyed with lead as a shielding material in nuclear reactors. However, just the use in permanent magnets , as u. a. are used in the generators of some types of wind power plants, has made these rare earth metals a rare raw material.

Other uses:

links

The category: Dysprosium compounds provides an overview of other dysprosium compounds .

Web links

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

Individual evidence

  1. ^ 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 webelements.com (Dysprosium) , unless otherwise stated .
  3. CIAAW, Standard Atomic Weights Revised 2013 .
  4. a b c d e Entry on dysprosium 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 13, 2020.
  5. a b c d e Entry on dysprosium at WebElements, https://www.webelements.com , accessed on June 13, 2020.
  6. ^ NN Greenwood, A. Earnshaw: Chemistry of the elements. 1st edition. VCH, Weinheim 1988, ISBN 3-527-26169-9 , p. 1579.
  7. 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.
  8. 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 .
  9. a b Entry on dysprosium, powder in the GESTIS substance database of the IFA , accessed on April 26, 2017(JavaScript required) .
  10. Dysprosium. www.americanelements.com, accessed on March 27, 2016 (English).
  11. Holmium. www.americanelements.com, accessed on March 27, 2016 (English).
  12. Oliver Langenscheidt: Electrodes for HID lamps - diagnostics and simulation. Witten 2008. urn : nbn: de: hbz: 294-23610