Isotopes of zirconium

Isotopes of zirconium (40Zr)
Main isotopes Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
88Zr synth 83.4 d ε 88Y
89Zr synth 78.36 h β+ 89Y
90Zr 51.5% stable
91Zr 11.2% stable
92Zr 17.1% stable
93Zr trace 1.61×106 y β− 93Nb
94Zr 17.4% stable
95Zr synth 64.032 d β− 95Nb
96Zr 2.80% 2.34×1019 y β−β− 96Mo
Standard atomic weight Ar°(Zr)

Naturally occurring zirconium (40Zr) is composed of four stable isotopes (one, 94Zr, may in the future be found radioactive), and one very long-lived radioisotope (96Zr), a primordial nuclide that decays via double beta decay with an observed half-life of 2.34 × 1019 years; it can also undergo single beta decay, which is not yet observed, but the theoretically predicted value of t1/2 is 2.4 × 1020 years. The second most stable radioisotope is 93Zr, which has a half-life of 1.61 million years. Thirty other radioisotopes have been observed from 77Zr to 114Zr; all have half-lives less than a day except for 95Zr (64.032 days), 88Zr (83.4 days), and 89Zr (78.36 hours). The most stable of the isomeric states is just 4.16 minutes for 89mZr.

Radioactive isotopes above the theoretically stable mass numbers 90-92 decay by electron emission resulting in niobium isotopes, whereas those below by positron emission or electron capture, resulting in yttrium isotopes.

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