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Zirconium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


                40              yttrium ← zirconium → niobium
                Ti
                ↑
                Zr
                ↓
                Hf

                                  Periodic Table - Extended Periodic Table

                                                                   General
                                    Name, Symbol, Number zirconium, Zr, 40
                                         Chemical series transition metals
                                              Group, Period, Block 4, 5, d
                                                  Appearance silvery white
                                              Atomic mass 91.224 (2) g/mol
                                     Electron configuration [Kr] 4d^2 5s^2
                                       Electrons per shell 2, 8, 18, 10, 2
                                                       Physical properties
                                                               Phase solid
                                       Density (near r.t.) 6.52 g·cm^−3
                                     Liquid density at m.p. 5.8 g·cm^−3
                                                     Melting point 2128  K
                                                    (1855 ° C, 3371 ° F)
                                                      Boiling point 4682 K
                                                    (4409 ° C, 7968 ° F)
                                            Heat of fusion 14 kJ·mol^−1
                                     Heat of vaporization 573 kJ·mol^−1
                          Heat capacity (25 °C) 25.36 J·mol^−1·K^−1

   CAPTION: Vapor pressure

                                      P/Pa   1    10  100  1 k  10 k 100 k
                                     at T/K 2639 2891 3197 3575 4053 4678

                                                         Atomic properties
                                               Crystal structure hexagonal
                                                        Oxidation states 4
                                                       ( amphoteric oxide)
                                    Electronegativity 1.33 (Pauling scale)
                                                       Ionization energies
                                           ( more) 1st: 640.1 kJ·mol^−1
                                                    2nd: 1270 kJ·mol^−1
                                                    3rd: 2218 kJ·mol^−1
                                                      Atomic radius 155 pm
                                              Atomic radius (calc.) 206 pm
                                                    Covalent radius 148 pm
                                                             Miscellaneous
                                                 Magnetic ordering no data
                                Electrical resistivity (20 °C) 421 nΩ·m
                       Thermal conductivity (300 K) 22.6 W·m^−1·K^−1
                        Thermal expansion (25 °C) 5.7 µm·m^−1·K^−1
                               Speed of sound (thin rod) (20 °C) 3800 m/s
                                                    Young's modulus 68 GPa
                                                      Shear modulus 33 GPa
                                                        Poisson ratio 0.34
                                                         Mohs hardness 5.0
                                                  Vickers hardness 903 MPa
                                                  Brinell hardness 650 MPa
                                             CAS registry number 7440-67-7
                                                         Selected isotopes

                CAPTION: Main article: Isotopes of zirconium

                            iso    NA    half-life    DM   DE ( MeV)  DP
                           ^88Zr syn    83.4 d      ε      -         ^88Y
                                                    γ      0.392 D   -
                           ^89Zr syn    78.4 h      ε      -         ^89Y
                                                    β^+    0.902     ^89Y
                                                    γ      0.909 D   -
                           ^90Zr 51.45% Zr is stable with 50 neutrons
                           ^91Zr 11.22% Zr is stable with 51 neutrons
                           ^92Zr 17.15% Zr is stable with 52 neutrons
                           ^93Zr syn    1.53×10^6y  β^-    0.060     ^93Nb
                           ^94Zr 17.38% Zr is stable with 54 neutrons
                           ^96Zr 2.8%   >3.9×10^20y β^-β^-  ?        ^96Mo

                                                                References

   Zirconium ( IPA: /zəˈkəʊniəm, ˌzɛːˈkəʊniəm/) is a chemical element in
   the modern periodic table that is assigned the symbol Zr and has the
   atomic number 40. A lustrous gray-white, strong transition metal that
   resembles titanium, zirconium is obtained chiefly from zircon and is
   very corrosion resistant. Zirconium is primarily used in nuclear
   reactors due to its resistance to corrosion and low neutron
   cross-section.

   == Notable characteristics It is a grayish-white metal, lustrous and
   exceptionally corrosion resistant. Zirconium is lighter than steel and
   its hardness is similar to copper. When it is finely divided, the metal
   can spontaneously ignite in air, especially at high temperatures (it is
   much more difficult to ignite the solid metal). Zirconium zinc alloy
   becomes magnetic at temperatures below 35 K. Oxidation state of
   zirconium is usually +4, although +3 and +2 can also be obtained.

Applications

   Cubic zirconia, ZrO2
   Enlarge
   Cubic zirconia, ZrO[2]

   The major end uses of zircon (ZrSiO[4]) are refractories, foundry sands
   (including investment casting), and ceramic opacification. Zircon is
   also marketed as a natural gemstone used in jewelry, and its oxide is
   processed to produce the diamond simulant, cubic zirconia (shown at
   left).

   Other uses:

     * Zirconium has a low absorption cross section for thermal neutrons,
       which makes it ideal for nuclear energy uses, such as cladding fuel
       elements. More than 90% of zirconium metal production is consumed
       by commercial nuclear power generation. Modern commercial scale
       reactors can use as much as a 150,000 meters of zirconium alloy (
       Zircaloy) tubing. Reactor-grade zirconium has to be purified of
       hafnium, which has 600 times higher neutron cross-section; a
       hafnium-free zirconium can be 10 times more expensive than
       zirconium with naturally occurring 1-5% of hafnium.
     * Extensively used by the chemical industry for piping in corrosive
       environments.
     * Zirconium is pyrophoric (flammable) and has been used in military
       incendiaries such as Dragon's Breath. It is also planned for use in
       the baseline variant of the AGM-154 Joint Standoff Weapon for
       incendiary effects.
     * Its carbonate was used in poison-ivy lotions until it was evident
       that many people are allergic. (allergies greatly vary between
       people)
     * Impure zirconium oxide, Zirconia, is used to make laboratory
       crucibles that can withstand heat shock, for linings of
       metallurgical furnaces, and by the ceramic and glass industries as
       a refractory material.
     * Human tissues can easily tolerate this metal which makes it
       suitable for biocompatible implants, eg. some artificial joints and
       limbs.
     * Also used in heat exchangers, as a " getter" in vacuum tubes, in
       lamp filaments and various specialty alloys.
     * When alloyed with niobium, zirconium becomes superconductive at low
       temperatures and is used to make superconductive magnets with
       possible large-scale electrical power uses.
     * Zirconium Diamide-Diamine complexes can be used to catalyse the
       polymerisation of alkenes, especially ethene, when activated with
       Trityl-BArF.
     * Zirconium nitride has been used more recently as an alternative to
       titanium nitride for coating drill bits. Both coatings are supposed
       to keep the bit sharper and cooler during cutting.
     * Bis(cyclopentadienyl)zirconium(IV) chloride hydride ( Schwartz's
       Reagent) is a commercially available metallocene used in the
       hydrozirconation of alkenes and alkynes.
     * Bicycle manufacturers incorporate zirconium-aluminium alloys in
       their high end bicycle frames. This combination provides the frame
       with tougher durability; likewise, the frame becomes lighter and
       much stronger. Zirconium is also used in the manufacture of high
       strength lacrosse sticks.
     * Zirconium is also applied in the molecule Aluminium Zirconium
       Octachlorohydrex GLY, also known as Anti-perspirant.

Hafnium-free zirconium

   Reactor-grade zirconium alloys must be made of purified zirconium free
   of hafnium contamination, as hafnium has very high neutron absorption
   cross-section, 600 times higher than zirconium. Commercial zirconium
   naturally contains 1-5% of hafnium which has to be removed. This
   removal process is difficult (zirconium and hafnium are two of the most
   difficult elements to separate). Two main process are in use:
   liquid-liquid extraction, exploiting the difference of solubility of
   metal thiocyanates in methyl isobutyl ketone, used mainly in United
   States, and extractive distillation, used primarily in Europe. The
   resulting reactor-grade zirconium is about 10 times as expensive as the
   hafnium-contaminated commercial grade. The separated hafnium is used
   for control rods. The zirconium is used mostly almost pure, in the form
   of low alloys, most often from the zircaloy group.

History

   Zirconium (Arabic zarkûn from Persian zargûn زرگون meaning "gold like")
   was discovered in 1789 by Martin Heinrich Klaproth and isolated in 1824
   by Jöns Jakob Berzelius.

   The zirconium-containing mineral zircon, or its variations (jargon,
   hyacinth, jacinth, or ligure), were mentioned in biblical writings. The
   mineral was not known to contain a new element until Klaproth analyzed
   a jargon from Ceylon in the Indian Ocean. He named the new element
   Zirkonertz (zirconia). The impure metal was isolated first by Berzelius
   by heating a mixture of potassium and potassium zirconium fluoride in a
   small decomposition process conducted in an iron tube. Pure zirconium
   wasn't prepared until 1914.

   The crystal bar process (or Iodide process), discovered by Anton Eduard
   van Arkel and Jan Hendrik de Boer in 1925, was the first industrial
   process for the commercial production of pure ductile metallic
   zirconium. It was superseded by the Kroll process.

Occurrence

   Zirconium is never found in nature as a free metal. The principal
   economic source of zirconium is the zirconium silicate mineral, zircon
   (ZrSiO[4]), which is found in deposits located in Australia, Brazil,
   India, Russia, and the United States. (It is extracted as a dark sooty
   powder, or as a gray metallic crystalline substance). Zirconium and
   hafnium are contained in zircon at a ratio of about 50 to 1 and are
   difficult to separate. Zircon is a coproduct or byproduct of the mining
   and processing of heavy-mineral sands for the titanium minerals,
   ilmenite and rutile, or tin minerals. Zirconium is also in 30 other
   recognized mineral species including baddeleyite. This metal is
   commercially produced by reduction of the Zirconium(IV) chloride with
   magnesium in the Kroll process, and through other methods.
   Commercial-quality zirconium still has a content of 1 to 3% hafnium.

   This element is also abundant in S-type stars and has been detected in
   the sun and meteorites. Lunar rock samples brought back from several
   Apollo program missions to the moon have a very high zirconium oxide
   content relative to terrestrial rocks.

Isotopes

   Naturally occurring zirconium is composed of four stable isotopes and
   one extremely long-lived radioisotope (^96Zr). The second most stable
   radioisotope is ^93Zr which has a half life of 1.53 million years.
   Eighteen other radioisotopes have been characterized. Most of these
   have half lives that are less than a day except ^95Zr (64.02 days),
   ^88Zr (63.4 days), and ^89Zr (78.41 hours). The primary decay mode is
   electron capture before ^92Zr and the primary mode after is beta decay.

Precautions

   Zirconium rod
   Enlarge
   Zirconium rod

   Compounds containing zirconium are not noted for toxicity. The metal
   dust can ignite in air and should be regarded as a major fire and
   explosion hazard. Zirconium has no biological role.

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