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66 terbiumdysprosiumholmium


Periodic Table - Extended Periodic Table
Name, Symbol, Number dysprosium, Dy, 66
Chemical series lanthanides
Group, Period, Block n/a, 6, f
Appearance silvery white
Atomic mass 162.500 (1) g/mol
Electron configuration [Xe] 4f10 6s2
Electrons per shell 2, 8, 18, 28, 8, 2
Physical properties
Phase solid
Density (near r.t.) 8.540 g·cm−3
Liquid density at m.p. 8.37 g·cm−3
Melting point 1680  K
(1407 ° C, 2565 ° F)
Boiling point 2840 K
(2567 ° C, 4653 ° F)
Heat of fusion 11.06 kJ·mol−1
Heat of vaporization 280 kJ·mol−1
Heat capacity (25 °C) 27.7 J·mol−1·K−1
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 1378 1523 (1704) (1954) (2304) (2831)
Atomic properties
Crystal structure hexagonal
Oxidation states 3
(weakly basic oxide)
Electronegativity 1.22 (Pauling scale)
Ionization energies
( more)
1st: 573.0 kJ·mol−1
2nd: 1130 kJ·mol−1
3rd: 2200 kJ·mol−1
Atomic radius 175 pm
Atomic radius (calc.) 228 pm
Magnetic ordering nonmagnetic at r.t.,
ferromagnetic under
liquid nitrogen
Electrical resistivity ( r.t.) (α, poly) 926 nΩ·m
Thermal conductivity (300 K) 10.7 W·m−1·K−1
Thermal expansion ( r.t.) (α, poly)
9.9 µm/(m·K)
Speed of sound (thin rod) (20 °C) 2710 m/s
Young's modulus (α form) 61.4 GPa
Shear modulus (α form) 24.7 GPa
Bulk modulus (α form) 40.5 GPa
Poisson ratio (α form) 0.247
Vickers hardness 540 MPa
Brinell hardness 500 MPa
CAS registry number 7429-91-6
Selected isotopes
Main article: Isotopes of dysprosium
iso NA half-life DM DE ( MeV) DP
154Dy syn 3.0×106y α 2.947 150Gd
156Dy 0.06% Dy is stable with 90 neutrons
158Dy 0.10% Dy is stable with 92 neutrons
160Dy 2.34% Dy is stable with 94 neutrons
161Dy 18.91% Dy is stable with 95 neutrons
162Dy 25.51% Dy is stable with 96 neutrons
163Dy 24.90% Dy is stable with 97 neutrons
164Dy 28.18% Dy is stable with 98 neutrons

Dysprosium ( IPA: /dɪsˈprəʊziəm/) is a chemical element in the periodic table that has the symbol Dy and atomic number 66.

Notable characteristics

Dysprosium is a rare earth element that has a metallic, bright silver luster, relatively stable in air at room temperature, but dissolving readily in dilute or concentrated mineral acids with the emission of hydrogen. It is soft enough to be cut with bolt-cutters (but not with a knife), and can be machined without sparking if overheating is avoided. Dysprosium's characteristics can be greatly affected even by small amounts of impurities.


Dysprosium is used, in conjunction with vanadium and other elements, in making laser materials. Its high thermal neutron absorption cross-section and melting point also suggests that it is useful for nuclear control rods. Dysprosium oxide (also known as dysprosia), with nickel cement compounds, which absorb neutrons readily without swelling or contracting under prolonged neutron bombardment, is used for cooling rods in nuclear reactors. Dysprosium-cadmium chalcogenides are sources of infrared radiation for studying chemical reactions. Furthermore, dysprosium is used for manufacturing compact discs. Because it is highly paramagnetic, dysprosium has been used as a contrast agent in magnetic resonance imaging.


Dysprosium was first identified in Paris in 1886 by French chemist Paul Émile Lecoq de Boisbaudran. However, the element itself was not isolated in relatively pure form until after the development of ion exchange and metallographic reduction techniques in the 1950s. The name dysprosium is derived from the Greek δυσπροσιτος [dysprositos] = "hard to obtain".


Dysprosium is never encountered as a free element, but is found in many minerals, including xenotime, fergusonite, gadolinite, euxenite, polycrase, blomstrandine, monazite and bastnasite; often with erbium and holmium or other rare earth elements.


Nearly all dysprosium compounds are in the +3 oxidation state, and are highly paramagnetic. Dysprosium compounds include:

  • Fluorides
    • DyF3
  • Chlorides
    • DyCl2
    • DyCl3
  • Bromides
    • DyBr2
    • DyBr3
  • Iodides
    • DyI2
    • DyI3
  • Oxides
    • Dy2O3
  • Sulfides
    • Dy2S3
  • Nitrides
    • DyN


Naturally occurring dysprosium is composed of 7 stable isotopes, 156-Dy, 158-Dy, 160-Dy, 161-Dy, 162-Dy, 163-Dy and 164-Dy, with 164-Dy being the most abundant (28.18% natural abundance). 28 radioisotopes have been characterized, with the most stable being 154-Dy with a half-life of 3.0E+6 years, 159-Dy with a half-life of 144.4 days, and 166-Dy with a half-life of 81.6 hours. All of the remaining radioactive isotopes have half-lifes that are less than 10 hours, and the majority of these have half lifes that are less than 30 seconds. This element also has 5 meta states, with the most stable being 165m-Dy (t½ 1.257 minutes), 147m-Dy (t½ 55.7 seconds) and 145m-Dy (t½ 13.6 seconds).

The primary decay mode before the most abundant stable isotope, 164-Dy, is electron capture, and the primary mode after is beta minus decay. The primary decay products before 164-Dy are terbium isotopes, and the primary products after are holmium isotopes.


As with the other lanthanides, dysprosium compounds are of low to moderate toxicity, although their toxicity has not been investigated in detail. Dysprosium does not have any known biological properties.

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