Zirconium

Zirconium - Zr

CAS: 7440-67-7
Description: Grayish-white metal
Classification: Transition Metal
Date of Discovery: 1789
Discoverer: Martin Klaproth
Name Origin: Persian zargun, "gold like"

Atomic Number: 40
Number of Neutrons: 51
Atomic Mass: 91.224(2) amu
Melting Point: 1855 ± 2 °C
Boiling Point: 4409 °C
Density (293 K): 6.506 g/cm³
Atomic volume: 14.1 cm³/mol
Electrical resistivity: 0.0236 10^-6/cm

Thermal conductivity: 0.227 W/cmK
Enthalpy of atomization: 598 kJ/mol (est.)
Enthalpy of vaporization: 581.6 kJ/mol
Enthalpy of fusion: 16.90 kJ/mol
Specific heat capacity: 0.27 J/gK

Energy levels: 2-8-18-10-2
Electron configuration: [Kr]4d²5s²
Crystal Structure: Hexagonal
Atomic radius: 2.16 Å
Covalent radius: 1.45 Å
Oxidation States: +2, +3, +4
Electronegativity, Pauling: 1.33
Electron affinity: 0.426 eV
First ionization energy: 6.84 eV
2nd ionization energy: 13.13 eV
3rd ionization energy: 22.99 eV
Polarizability: 17.9 10^-24cm³

Isotope	Natural Abundance	Atomic Mass	Half-life	Decay Mode	Spin
⁸⁰Zr	79.9406	⁺
⁸¹Zr	80.9368	15 s	⁺
⁸²Zr	81.9311	32 s	⁺
^83mZr	7 s	⁺	(7/2+)
⁸³Zr	82.9287	44 s	⁺; EC	(1/2-)
⁸⁴Zr	83.9233	26 m	⁺; EC	0+
^85mZr	10.9 s	IT; ⁺	1/2-
⁸⁵Zr	84.9215	7.9 m	⁺; EC	7/2+
⁸⁶Zr	85.91647	16.5 h	EC	0+
^87mZr	14.0 s	IT	1/2-
⁸⁷Zr	86.91482	1.73 h	⁺; EC	9/2+
⁸⁸Zr	87.91023	83.4 d	EC	0+
^89mZr	4.18 m	IT; ⁺; EC	1/2-
⁸⁹Zr	88.908889	3.27 d	⁺; EC	9/2+
^90mZr	0.809 s	IT	5-
⁹⁰Zr	51.45(3)	89.904702	Stable	0+
⁹¹Zr	11.22(4)	90.905643	Stable	5/2+
⁹²Zr	17.15(2)	91.905039	Stable	0+
⁹³Zr	92.906474	1.5 x 10⁶ y	^-	5/2+
⁹⁴Zr	17.38(4)	93.906314	Stable	0+
⁹⁵Zr	94.908041	64.02 d	^-	5/2+
⁹⁶Zr	2.80(2)	95.908275	Stable	0+
⁹⁷Zr	96.910950	16.8 h	^-	1/2-
⁹⁸Zr	97.91276	30.7 s	^-	0+
⁹⁹Zr	98.91651	2.2 s	^-	1/2+
¹⁰⁰Zr	99.91776	7.1 s	^-	0+
¹⁰¹Zr	100.92114	2.1 s	^-	3/2-
¹⁰²Zr	101.92298	2.9 s	^-
¹⁰³Zr	102.9266	1.3 s	^-
¹⁰⁴Zr	103.9288	1.2 s	^-
¹⁰⁵Zr	104.9331	1 s	^-
The name zircon probably originated from the Persian word zargun, which describes the color of the gemstone now known as zircon, jargon, hyacinth, jacinth, or ligure. This mineral, or its variations, is mentioned in biblical writings. The mineral was not known to contain a new element until Klaproth, in 1789, analyzed a jargon from Ceylon and found a new earth, which Werner named zircon (silex circonius), and Klaproth called Zirkonerde (zirconia). The impure metal was first isolated by Berzelius in 1824 by heating a mixture of potassium and potassium zirconium fluoride in a small iron tube. Pure zirconium was first prepared in 1914. Very pure zirconium was first produced in 1925 by van Arkel and de Boer, by an iodide decomposition process they developed. Zirconium is found in abundance in S-type stars, and has been identified in the sun and meteorites. Analyses of lunar rock samples obtained during the various Apollo missions to the moon show a surprisingly high zirconium oxide content, compared with terrestial rocks. Naturally occurring zirconium contains five isotopes. Twenty six other radioactive isotopes and isomers are known to exist. Zircon, ZrSiO₄, the principal ore, is found in deposits in Florida, South Carolina, Australia, and Brazil. Baddeleyite, found in Brazil, is an important zirconium mineral. It is principally pure ZrO₂ in crystalline form having a hafnium content of about 1%. Zirconium also occurs in some 30 other recognized mineral species. Zirconium is produced commercially by reduction of the chloride with magnesium (the Kroll Process), and by other methods. It is a grayish-white lustrous metal. When finely divided, the metal may ignite spontaneously in air, especially at elevated temperatures. The solid metal is much more difficult to ignite. The inherent toxicity of zirconium compounds is low. Hafnium is invariably found in zirconium ores, and the separation is difficult. Commercial-grade zirconium contains from 1 to 3% hafnium. Zirconium has a low absorption cross section for neutrons, and is therefore used for nuclear energy applications, such as for cladding fuel elements. Commercial nuclear power generation now takes more than 90% of zirconium metal production. Reactors of the size now being made may use as much as a half-million lineal feet of zirconium alloy tubing. Reactor-grade zirconium is essentially free of hafnium. Zircaloy(R) is an important alloy developed specifically for nuclear applications. Zirconium is exceptionally resistant to corrosion by many common acids and alkalis, by sea water, and by other agents. It is used extensively by the chemical industry where corrosive agents are employed. Zirconium is used as a getter in vacuum tubes as an alloying agent in steel, in surgical appliances, photoflash bulbs, explosive primers, rayon spinnerets, lamp filaments, etc. It is used in poison ivy lotions in the form of the carbonate as it combines with urushiol. With niobium, zirconium is superconductive at low temperatures and is used to make superconductive magnets, which offer hope of direct large-scale generation of electric power. Alloyed with zinc, zirconium becomes magnetic at temperatures below 35 K. Zirconium oxide (zircon) has a high index of refraction and is used as a gem material. The impure oxide, zirconia, is used for laboratory crucibles that will withstand heat shock, for linings of metallurgical furnaces, and by the glass and ceramic industries as a refractory material. Its use as a refractory material accounts for a large share of all zirconium consumed. LINKS: Zirconium Dioxide AMM Online - Zirconium Profile Summary - Thermal Conductivity of Zirconium Return Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998.

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