Neodymium
From Freepedia
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| Name, Symbol, Number | neodymium, Nd, 60 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Chemical series | lanthanides | ||||||||||||||||||||||||||||||||||||||||||||||||
| Group, Period, Block | ?, 6, f | ||||||||||||||||||||||||||||||||||||||||||||||||
| Appearance | silvery white, yellowish tinge Image:Nd,60.jpg | ||||||||||||||||||||||||||||||||||||||||||||||||
| 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/cm³ | ||||||||||||||||||||||||||||||||||||||||||||||||
| Liquid density at m.p. | 6.89 g/cm³ | ||||||||||||||||||||||||||||||||||||||||||||||||
| Melting point | 1297 K (1024 °C, 1875 °F) | ||||||||||||||||||||||||||||||||||||||||||||||||
| Boiling point | 3347 K (3074 °C, 5565 °F) | ||||||||||||||||||||||||||||||||||||||||||||||||
| Heat of fusion | 7.14 kJ/mol | ||||||||||||||||||||||||||||||||||||||||||||||||
| Heat of vaporization | 289 kJ/mol | ||||||||||||||||||||||||||||||||||||||||||||||||
| Heat capacity | (25 °C) 27.45 J/(mol·K) | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Atomic properties | |||||||||||||||||||||||||||||||||||||||||||||||||
| Crystal structure | hexagonal | ||||||||||||||||||||||||||||||||||||||||||||||||
| Oxidation states | 3 (mildly basic oxide) | ||||||||||||||||||||||||||||||||||||||||||||||||
| Electronegativity | 1.14 (Pauling scale) | ||||||||||||||||||||||||||||||||||||||||||||||||
| Ionization energies (more) | 1st: 533.1 kJ/mol | ||||||||||||||||||||||||||||||||||||||||||||||||
| 2nd: 1040 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||||||
| 3rd: 2130 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||||||
| Atomic radius | 185 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
| Atomic radius (calc.) | 206 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
| Miscellaneous | |||||||||||||||||||||||||||||||||||||||||||||||||
| Magnetic ordering | ? | ||||||||||||||||||||||||||||||||||||||||||||||||
| Electrical resistivity | (r.t.) (α, poly) 643 nΩ·m | ||||||||||||||||||||||||||||||||||||||||||||||||
| Thermal conductivity | (300 K) 16.5 W/(m·K) | ||||||||||||||||||||||||||||||||||||||||||||||||
| 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 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Notable isotopes | |||||||||||||||||||||||||||||||||||||||||||||||||
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| References | |||||||||||||||||||||||||||||||||||||||||||||||||
Neodymium is a chemical element in the periodic table that has the symbol Nd and atomic number 60.
Contents |
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.
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), and 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 in-ear headphones and computer hard drives.
- Neodymium ions are used in active laser media.
- Probably because of similarities to Ca2+, Nd3+ has been reported [1] 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
- Chlorides
- Bromides
- Iodides
- Oxides
- Sulfides
- Selenides
- Tellurides
- Nitrides
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.
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.
