Neodymium

60 praseodymiumneodymiumpromethium
-

Nd

U
Periodic Table - Extended Periodic Table
General
Name, Symbol, Number neodymium, Nd, 60
Chemical series lanthanides
Group, Period, Block n/a, 6, f
Appearance silvery white,
yellowish tinge
Atomic mass 144.242(3) g/mol
Electron configuration [Xe] 4f4 6s2
Electrons per shell 2, 8, 18, 22, 8, 2
Physical properties
Phase solid
Density (near r.t.) 7.01 g·cm−3
Liquid density at m.p. 6.89 g·cm−3
Melting point 1297 K
(1024 °C, 1875 °F)
Boiling point 3347 K
(3074 °C, 5565 °F)
Heat of fusion 7.14 kJ·mol−1
Heat of vaporization 289 kJ·mol−1
Heat capacity (25 °C) 27.45 J·mol−1·K−1
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 1595 1774 1998 (2296) (2715) (3336)
Atomic properties
Crystal structure hexagonal
Oxidation states 3
(mildly basic oxide)
Electronegativity 1.14 (Pauling scale)
Ionization energies
(more)
1st: 533.1 kJ·mol−1
2nd: 1040 kJ·mol−1
3rd: 2130 kJ·mol−1
Atomic radius 185 pm
Atomic radius (calc.) 206 pm
Miscellaneous
Magnetic ordering ferromagnetic
Electrical resistivity (r.t.) (α, poly) 643 nΩ·m
Thermal conductivity (300 K) 16.5 W·m−1·K−1
Thermal expansion (r.t.) (α, poly)
9.6 µm/(m·K)
Speed of sound (thin rod) (20 °C) 2330 m/s
Young's modulus (α form) 41.4 GPa
Shear modulus (α form) 16.3 GPa
Bulk modulus (α form) 31.8 GPa
Poisson ratio (α form) 0.281
Vickers hardness 343 MPa
Brinell hardness 265 MPa
CAS registry number 7440-00-8
Selected isotopes
Main article: Isotopes of neodymium
iso NA half-life DM DE (MeV) DP
142Nd 27.13% Nd is stable with 82 neutrons
143Nd 12.18% Nd is stable with 83 neutrons
144Nd 23.8% 2.29×1015y α 1.905 140Ce
145Nd 8.3% Nd is stable with 85 neutrons
146Nd 17.19% Nd is stable with 86 neutrons
148Nd 5.76% Nd is stable with 88 neutrons
150Nd 5.64% 1.1×1019y β-β- 3.367 150Sm
References

Neodymium (IPA: /ˌniːə(ʊ)ˈdɪmiəm, ˌniə(ʊ)-/) is a chemical element in the periodic table that has the symbol Nd and atomic number 60.

Contents

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Notable characteristics

Neodymium, a rare earth metal, is present in misch metal to the extent of about 18%. The metal has a bright silvery metallic luster; however, being one of the more reactive rare earth metals, neodymium quickly tarnishes in air, forming an oxide that falls off and exposes the metal to further oxidation. Although belonging to rare earth metals, neodymium is not rare at all. It constitutes 38 ppm of Earth’s crust.

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Applications

Uses of neodymium include

Neodymium doped glass slabs used in extremely powerful lasers for inertial confinement fusion.
Neodymium doped glass slabs used in extremely powerful lasers for inertial confinement fusion.
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History

Neodymium was discovered by Baron Carl Auer von Welsbach, an Austrian chemist, in Vienna in 1885. He separated neodymium, as well as the element praseodymium, from a material known as didymium by means of spectroscopic analysis; however, it was not isolated in relatively pure form until 1925. The name neodymium is derived from the Greek words neos, new, and didymos, twin. Neodymium is frequently misspelled as neodynium.

Today, neodymium is primarily obtained through an ion exchange process of monazite sand ((Ce,La,Th,Nd,Y)PO4), a material rich in rare earth elements, and through electrolysis of its halide salts.

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Occurrence

Neodymium is never found in nature as the free element; rather, it occurs in ores such as monazite sand ((Ce,La,Th,Nd,Y)PO4) and bastnasite ((Ce,La,Th,Nd,Y)(CO3)F) that contain small amounts of all the rare earth metals. Neodymium can also be found in Misch metal; it is difficult to separate it from other rare earth elements.

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Compounds

Neodymium compounds include

See also neodymium compounds.

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Isotopes

Naturally occurring Neodymium is composed of 5 stable isotopes, 142Nd, 143Nd, 145Nd, 146Nd and 148Nd, with 142Nd being the most abundant (27.2% natural abundance), and 2 radioisotopes, 144Nd and 150Nd. In all, 31 radioisotopes of Neodymium have been characterized, with the most stable being 150Nd with a half-life (T½) of >1.1×1019 years, 144Nd with a half-life of 2.29×1015 years, and 147Nd with a half-life of 10.98 days. All of the remaining radioactive isotopes have half-lives that are less than 3.38 days, and the majority of these have half-lives that are less than 71 seconds. This element also has 4 meta states with the most stable being 139Ndm (T½ 5.5 hours), 135Ndm (T½ 5.5 minutes) and 141Ndm (T½ 62.0 seconds).

The primary decay mode before the most abundant stable isotope, 142Nd, is electron capture and the primary mode after is beta minus decay. The primary decay products before 142Nd are element Pr (praseodymium) isotopes and the primary products after are element Pm (promethium) isotopes.

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Precautions

Neodymium metal dust is a combustion and explosion hazard.

Neodymium compounds, like all rare earth metals, are of low to moderate toxicity; however its toxicity has not been thoroughly investigated. Neodymium dust and salts are very irritating to the eyes and mucous membranes, and moderately irritating to skin. Breathing the dust can cause lung embolisms, and accumulated exposure damages the liver. Neodymium also acts as an anticoagulant, especially when given intravenously.

Neodymium magnets have been tested for medical uses such as magnetic braces and bone repair, but biocompatibility issues have prevented widespread application.

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See also

Neodymium magnet (NIB or NdFeB)

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References

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External links

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