Isotopes of zirconium

Naturally occurring zirconium (Zr) is composed of four stable isotopes, and one extremely long-lived radioisotope (⁹⁶Zr), which decays via double beta decay with the observed half-life of 2.0×10¹⁹ years [http://www.nndc.bnl.gov/bbdecay/list.html] ; it can also undergo single beta decay which is not yet observed, but the theoretically predicted value of "T"_½ is 2.4×10²⁰ years [http://www.iop.org/EJ/abstract/0954-3899/34/5/005/] . The second most stable radioisotope is ⁹³Zr which has a half-life of 1.53 million years. Eighteen other radioisotopes have been observed. Most of these have half-lives that are less than a day except for ⁹⁵Zr (64.02 days), ⁸⁸Zr (63.4 days), and ⁸⁹Zr (78.41 hours). The primary decay mode is electron capture for isotopes lighter than ⁹²Zr, and the primary mode for heavier isotopes is beta decay.
Standard atomic mass: 91.224(2) u.

Zircornium is the heaviest element that can be formed from symmetric fusion, from either ⁴⁵Sc, or ⁴⁶Ca producing ⁹⁰Zr and ⁹²Zr respectively. All heavier elements are formed either through asymmetric fusion or during the collapse of supernovae.

Table

Notes

* Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
* Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
* Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

* Isotope masses from [http://www.nndc.bnl.gov/amdc/index.html Ame2003 Atomic Mass Evaluation] by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in "Nuclear Physics" A729 (2003).
* Isotopic compositions and standard atomic masses from [http://www.iupac.org/publications/pac/2003/7506/7506x0683.html Atomic weights of the elements. Review 2000 (IUPAC Technical Report)] . "Pure Appl. Chem." Vol. 75, No. 6, pp. 683-800, (2003) and [http://www.iupac.org/news/archives/2005/atomic-weights_revised05.html Atomic Weights Revised (2005)] .
* Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
** Audi, Bersillon, Blachot, Wapstra. [http://amdc.in2p3.fr/web/nubase_en.html The Nubase2003 evaluation of nuclear and decay properties] , Nuc. Phys. A 729, pp. 3-128 (2003).
** National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the [http://www.nndc.bnl.gov/nudat2/ NuDat 2.1 database] (retrieved Sept. 2005).
** David R. Lide (ed.), Norman E. Holden in "CRC Handbook of Chemistry and Physics, 85th Edition", online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.