Neodymium

Praseodymium – Neodymium – Promethium Nd U       Missing image Nd-TableImage.png Image:Nd-TableImage.png Full table
General
Name, Symbol, Number	Neodymium, Nd, 60
Chemical series	Lanthanides
Group, Period, Block	_ , 6, f
Density, Hardness	6800 kg/m3, no data
Appearance	silvery white, yellowish tinge Missing image Nd,60.jpg
Atomic properties
Atomic weight	144.24(3) amu
Atomic radius (calc.)	185 (206) pm
Covalent radius	no data
van der Waals radius	no data
Electron configuration	[Xe]4f46s²
e- 's per energy level	2, 8, 18, 22, 8, 2
Oxidation states (Oxide)	3 (mildly basic)
Crystal structure	Hexagonal
Physical properties
State of matter	solid (__)
Melting point	1297 K (1875 ?F)
Boiling point	3373 K (5612 ?F)
Molar volume	20.59 ×10-6 m3/mol
Heat of vaporization	273 kJ/mol
Heat of fusion	7.14 kJ/mol
Vapor pressure	6.03E-3 Pa at 2890 K
Velocity of sound	2330 m/s at 293.15 K
Miscellaneous
Electronegativity	1.14 (Pauling scale)
Specific heat capacity	190 J/(kg*K)
Electrical conductivity	1.57 106/m ohm
Thermal conductivity	16.5 W/(m*K)
1st ionization potential	533.1 kJ/mol
2nd ionization potential	1040 kJ/mol
3rd ionization potential	2130 kJ/mol
4th ionization potential	3900 kJ/mol
Most stable isotopes
iso NA half-life DM DE MeV DP 142Nd 27.13 142Nd is stable with 82 neutrons 143Nd 12.18 143Nd is stable with 83 neutrons 144Nd 23.8 2.29E15 y α 1.905 140Ce 145Nd 8.3 145Nd is stable with 85 neutrons 146Nd 17.19 146Nd is stable with 86 neutrons 148Nd 5.76 148Nd is stable with 88 neutrons 150Nd 5.64 1.1E19 y β-β- 3.367 150Sm
SI units & STP are used except where noted.

Neodymium is a chemical element in the periodic table that has the symbol Nd and atomic number 60.

Contents

1 Notable characteristics 2 Applications 3 History 4 Occurrence 5 Compounds 6 Isotopes 7 Precautions 8 References 9 External links

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 spalls off and exposes the metal to further oxidation.

Applications

Uses of neodymium include:

• Neodymium is a component of didymium used for colouring glass to make welder's goggles.
• Neodymium colours glass in delicate shades ranging from pure violet through wine-red and warm gray. Light transmitted through such glass shows unusually sharp absorption bands; the glass is used in astronomical work to produce sharp bands by which spectral lines may be calibrated. Neodymium is also used to remove the green colour caused by iron contaminants from glass.
• Certain transparent materials with a small concentration of neodymium ions can be used in lasers for infrared wavelengths (1054-1064 nm), e.g. Nd:YAG (yttrium aluminium garnet), Nd:YLF (yttrium lithium fluoride), Nd:YVO₄ (yttrium orthvanadate), Nd:glass.
• Neodymium salts are used as a colourant for enamels.
• Neodymium is used in very powerful permanent magnets - Nd₂Fe₁₄B. These magnets are cheaper and also stronger than samarium-cobalt magnets. Neodymium magnets appear in products such as Sennheiser or iPod in-ear headphones.
• Neodymium ions are used in active laser media.
• Probably because of similarities to Ca²⁺, Nd³⁺ has been reported [1] (http://www.regional.org.au/au/gcirc/2/399.htm) to promote plant growth. Rare earth element compounds are frequently used in China as fertilizer.

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.

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.

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.

Compounds

Neodymium compounds include:

• Fluorides
  • NdF₃
• Chlorides
  • NdCl₂
  • NdCl₃
• Bromides
  • NdBr₂
  • NdBrs₃
• Iodides
  • NdI₂
  • NdI₃
• Oxides
  • Nd₂O₃
• Sulfides
  • NdS
  • Nd₂S₃
• Selenides
  • NdSe
• Tellurides
  • NdTe
  • Nd₂Te₃
• Nitrides
  • NdN

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 (T_?) 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 ¹³⁹Nd^m (T_? 5.5 hours), ¹³⁵Nd^m (T_? 5.5 minutes) and ¹⁴¹Nd^m (T_? 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.

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.

References

• Los Alamos National Laboratory - Neodymium (http://periodic.lanl.gov/elements/60.html)

External links

• WebElements.com – Neodymium (http://www.webelements.com/webelements/elements/text/Nnd/index.html)
• EnvironmentalChemistry.com – Neodymium (http://environmentalchemistry.com/yogi/periodic/Nd.html)
• It's Elemental – Neodymium (http://education.jlab.org/itselemental/ele060.html)