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Neodymium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


                60          praseodymium ← neodymium → promethium
                 -
                ↑
                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] 4f^4 6s^2
                                    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

   CAPTION: 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

                CAPTION: 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%  2.29×10^15y 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%  1.1×10^19y  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.

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.

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 grey. 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.
     * Neodymium salts are used as a colourant for enamels.
     * Neodymium is used in the strongest permanent magnets known -
       Nd[2]Fe[14]B. These magnets are cheaper, lighter, and stronger than
       samarium-cobalt magnets. Neodymium magnets appear in high-quality
       products such as microphones, professional loudspeakers, in-ear
       headphones and computer hard disks where low mass, small volume, or
       strong magnetic fields are required.
     * Probably because of similarities to Ca^2+, Nd^3+ has been reported
       to promote plant growth. Rare earth element compounds are
       frequently used in China as fertilizer.
     * Size and strength of volcanic eruption can be predicted by scanning
       for neodymium isotopes. Small and large volcanic eruptions produce
       lava with different neodymium isotope composition. From the
       composition of isotopes, scientists predict how big the coming
       eruption will be, and use this information to warn residents of the
       intensity of the eruption.
     * Certain transparent materials with a small concentration of
       neodymium ions can be used in lasers as gain media for infrared
       wavelengths (1054-1064 nm), e.g. Nd:YAG (yttrium aluminium garnet),
       Nd:YLF (yttrium lithium fluoride), Nd:YVO[4] (yttrium
       orthvanadate), and Nd:glass. The current laser at the UK Atomic
       Weapons Establishment (AWE), the HELEN 1-TW neodymium-glass laser,
       can access the midpoints of pressure and temperature regions and is
       used to acquire data for modelling on how density, temperature and
       pressure interact inside warheads. HELEN can create plasmas of
       around 10^6 K, from which opacity and transmission of radiation are
       measured.
     * Neodymium glass (Nd:Glass) solid-state lasers are used in extremely
       high power ( terawatt scale), high energy ( megajoules) multiple
       beam systems for inertial confinement fusion. Nd:Glass lasers are
       usually frequency tripled to the third harmonic at 351 nm in laser
       fusion devices.

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

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)PO[4]), 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)PO[4]) and
   bastnasite ((Ce,La,Th,Nd,Y)(CO[3])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
     * Halides
          + NdF[3]
          + NdCl[3]
          + NdBr[3]
          + NdI[3]
     * Oxides
          + Nd[2]O[3]
     * Sulfides
          + NdS
          + Nd[2]S[3]
     * 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[½]) of >1.1×10^19 years,
   ^144Nd with a half-life of 2.29×10^15 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[½] 5.5 hours), ^135Nd^m
   (T[½] 5.5 minutes) and ^141Nd^m (T[½] 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.

   Retrieved from " http://en.wikipedia.org/wiki/Neodymium"
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   with only minor checks and changes (see www.wikipedia.org for details
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