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Terbium - Dysprosium - Holmium
Name, Symbol, NumberDysprosium, Dy, 66
Chemical series Lanthanides
Group, Period, Block_ [?], 6 , f
Density, Hardness 8551 kg/m3, no data
Appearance silvery white
Atomic properties
Atomic weight 162.500(1) amu
Atomic radius (calc.) 175 (228) pm
Covalent radius no data
van der Waals radius no data
Electron configuration [Xe]6s²4f10
e- 's per energy level2, 8, 18, 28, 8, 2
Oxidation states (Oxide) 3 (weak base)
Crystal structure Hexagonal
Physical properties
State of matter solid (__)
Melting point 1680 K (2565 °F)
Boiling point 2840 K (4653 °F)
Molar volume 19.01 ×10-3 m3/mol
Heat of vaporization 230 kJ/mol
Heat of fusion 11.06 kJ/mol
Vapor pressure no data
Velocity of sound 2170 m/s at 293.15 K
Electronegativity 1.22 (Pauling scale)
Specific heat capacity 170 J/(kg*K)
Electrical conductivity 1.08 106/m ohm
Thermal conductivity 10.7 W/(m*K)
1st ionization potential 573.0 kJ/mol
2nd ionization potential 1130 kJ/mol
3rd ionization potential 2200 kJ/mol
4th ionization potential 3990 kJ/mol
Most stable isotopes
isoNAhalf-life DMDE MeVDP
154Dy{syn.}3.0E+6 yα2.947150Gd
156Dy0.06%156Dy is stable with 90 neutrons
158Dy0.10%158Dy is stable with 92 neutrons
160Dy2.34%160Dy is stable with 94 neutrons
161Dy18.91%161Dy is stable with 95 neutrons
162Dy25.51%162Dy is stable with 96 neutrons
163Dy24.90%163Dy is stable with 97 neutrons
164Dy28.18%164Dy is stable with 98 neutrons
SI units & STP are used except where noted.
Dysprosium is a chemical element in the periodic table that has the symbol Dy and atomic number 66.

Table of contents

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 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, for making laser materials; its high thermal neutron absorption cross-section and melting point also suggest using it for nuclear control rods[?], and a Dysprosium oxide-Nickel cermet[?], which absorbs neutrons readily without swelling or contracting under prolonged neutron bombardment, is being used for cooling nuclear reactor rods[?]. Dysprosium-Cadmium chalcogenides[?] are sources of infrared radiation for studying chemical reactions; furthermore, Dysprosium is used for manufacturing compact discs.


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 Greek dysprositos, "hard to get at".

Biological role

Dysprosium does not have any known biological properties.


Dysprosium is never encountered as the 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.


Dysprosium compounds include:


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 (t˝ 1.257 minutes), 147m-Dy (t˝ 55.7 seconds) and 145m-Dy (t˝ 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 element Tb (Terbium) isotopes, and the primary products after are element Ho (Holmium) isotopes.


All dysprosium compounds should be regarded as highly toxic. The metal dust presents a fire and explosion hazard.

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