Isotopes of zirconium

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 t_1/2 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.

List of isotopes

|-id=Zirconium-77 | ⁷⁷Zr | style="text-align:right" | 40 | style="text-align:right" | 37 | 76.96608(43)# | 100#&nbsp;μs | | | 3/2−# | | |-id=Zirconium-78 | ⁷⁸Zr | style="text-align:right" | 40 | style="text-align:right" | 38 | 77.95615(43)# | 50#&nbsp;ms<br/>[>200&nbsp;ns] | | | 0+ | | |-id=Zirconium-79 | ⁷⁹Zr | style="text-align:right" | 40 | style="text-align:right" | 39 | 78.94979(32)# | 56(30)&nbsp;ms | β⁺ | ⁷⁹Y | 5/2+# | | |-id=Zirconium-80 | ⁸⁰Zr | style="text-align:right" | 40 | style="text-align:right" | 40 | 79.940818(86) | 4.6(6)&nbsp;s | β⁺ | ⁸⁰Y | 0+ | | |-id=Zirconium-81 | rowspan=2|⁸¹Zr | rowspan=2 style="text-align:right" | 40 | rowspan=2 style="text-align:right" | 41 | rowspan=2|80.938211(11) | rowspan=2|5.5(4)&nbsp;s | β⁺ (99.88%) | ⁸¹Y | rowspan=2|(3/2−) | rowspan=2| | rowspan=2| |- | β⁺, p (0.12%) | ⁸⁰Sr |-id=Zirconium-82 | ⁸²Zr | style="text-align:right" | 40 | style="text-align:right" | 42 | 81.9317075(17) | 32(5)&nbsp;s | β⁺ | ⁸²Y | 0+ | | |-id=Zirconium-83 | rowspan=2|⁸³Zr | rowspan=2 style="text-align:right" | 40 | rowspan=2 style="text-align:right" | 43 | rowspan=2|82.92923591(70) | rowspan=2|42(2)&nbsp;s | β⁺ | ⁸³Y | rowspan=2|1/2−# | rowspan=2| | rowspan=2| |- | β⁺, p (?%) | ⁸²Sr |-id=Zirconium-83m1 | style="text-indent:1em" | ^83m1Zr | colspan="3" style="text-indent:2em" | 52.72(5)&nbsp;keV | 0.53(12)&nbsp;μs | IT | ⁸³Zr | (5/2−) | | |-id=Zirconium-83m2 | style="text-indent:1em" | ^83m2Zr | colspan="3" style="text-indent:2em" | 77.04(7)&nbsp;keV | 1.8(1)&nbsp;μs | IT | ⁸³Zr | (7/2+) | | |-id=Zirconium-84 | ⁸⁴Zr | style="text-align:right" | 40 | style="text-align:right" | 44 | 83.9233257(59) | 25.8(5)&nbsp;min | β⁺ | ⁸⁴Y | 0+ | | |-id=Zirconium-85 | ⁸⁵Zr | style="text-align:right" | 40 | style="text-align:right" | 45 | 84.9214432(69) | 7.86(4)&nbsp;min | β⁺ | ⁸⁵Y | (7/2+) | | |-id=Zirconium-85m | rowspan=2 style="text-indent:1em" | ^85mZr | rowspan=2 colspan="3" style="text-indent:2em" | 292.2(3)&nbsp;keV | rowspan=2|10.9(3)&nbsp;s | IT (?%) | ⁸⁵Zr | rowspan=2|1/2−# | rowspan=2| | rowspan=2| |- | β⁺ (?%) | ⁸⁵Y |-id=Zirconium-86 | ⁸⁶Zr | style="text-align:right" | 40 | style="text-align:right" | 46 | 85.9162968(38) | 16.5(1)&nbsp;h | β⁺ | ⁸⁶Y | 0+ | | |-id=Zirconium-87 | ⁸⁷Zr | style="text-align:right" | 40 | style="text-align:right" | 47 | 86.9148173(45) | 1.68(1)&nbsp;h | β⁺ | ⁸⁷Y | 9/2+ | | |-id=Zirconium-87m | style="text-indent:1em" | ^87mZr | colspan="3" style="text-indent:2em" | 335.84(19)&nbsp;keV | 14.0(2)&nbsp;s | IT | ⁸⁷Zr | 1/2− | | |- | ⁸⁸Zr | style="text-align:right" | 40 | style="text-align:right" | 48 | 87.9102207(58) | 83.4(3)&nbsp;d | EC | ⁸⁸Y | 0+ | | |-id=Zirconium-88m | style="text-indent:1em" | ^88mZr | colspan="3" style="text-indent:2em" | 2887.79(6)&nbsp;keV | 1.320(25)&nbsp;μs | IT | ⁸⁸Zr | 8+ | | |- | ⁸⁹Zr | style="text-align:right" | 40 | style="text-align:right" | 49 | 88.9088798(30) | 78.360(23)&nbsp;h | β⁺ | ⁸⁹Y | 9/2+ | | |-id=Zirconium-89m | rowspan=2 style="text-indent:1em" | ^89mZr | rowspan=2 colspan="3" style="text-indent:2em" | 587.82(10)&nbsp;keV | rowspan=2|4.161(10)&nbsp;min | IT (93.77%) | ⁸⁹Zr | rowspan=2|1/2− | rowspan=2| | rowspan=2| |- | β⁺ (6.23%) | ⁸⁹Y |-id=Zirconium-90 | ⁹⁰Zr | style="text-align:right" | 40 | style="text-align:right" | 50 | 89.90469876(13) | colspan=3 align=center|Stable | 0+ | 0.5145(4) | |-id=Zirconium-90m1 | style="text-indent:1em" | ^90m1Zr | colspan="3" style="text-indent:2em" | 2319.000(9)&nbsp;keV | 809.2(20)&nbsp;ms | IT | ⁹⁰Zr | 5- | | |-id=Zirconium-90m2 | style="text-indent:1em" | ^90m2Zr | colspan="3" style="text-indent:2em" | 3589.418(15)&nbsp;keV | 131(4)&nbsp;ns | IT | ⁹⁰Zr | 8+ | | |-id=Zirconium-91 | ⁹¹Zr | style="text-align:right" | 40 | style="text-align:right" | 51 | 90.90564021(10) | colspan=3 align=center|Stable | 5/2+ | 0.1122(5) | |-id=Zirconium-91m | style="text-indent:1em" | ^91mZr | colspan="3" style="text-indent:2em" | 3167.3(4)&nbsp;keV | 4.35(14)&nbsp;μs | IT | ⁹¹Zr | (21/2+) | | |-id=Zirconium-92 | ⁹²Zr | style="text-align:right" | 40 | style="text-align:right" | 52 | 91.90503534(10) | colspan=3 align=center|Stable | 0+ | 0.1715(3) | |- | rowspan=2 | ⁹³Zr | rowspan=2 style="text-align:right" | 40 | rowspan=2 style="text-align:right" | 53 | rowspan=2 | 92.90647066(49) | rowspan=2 | 1.61(5)×10⁶&nbsp;y | β^− (73%) | ^93m1Nb | rowspan=2 | 5/2+ | rowspan=2 | | rowspan=2 | |- | β^− (27%) | ⁹³Nb |-id=Zirconium-94 | ⁹⁴Zr | style="text-align:right" | 40 | style="text-align:right" | 54 | 93.90631252(18) | colspan=3 align=center|Observationally stable | 0+ | 0.1738(4) | |-id=Zirconium-95 | ⁹⁵Zr | style="text-align:right" | 40 | style="text-align:right" | 55 | 94.90804028(93) | 64.032(6)&nbsp;d | β^− | ⁹⁵Nb | 5/2+ | | |-id=Zirconium-96 | ⁹⁶Zr | style="text-align:right" | 40 | style="text-align:right" | 56 | 95.90827762(12) | 2.34(17)×10¹⁹&nbsp;y | β^−β^− | ⁹⁶Mo | 0+ | 0.0280(2) | |-id=Zirconium-97 | ⁹⁷Zr | style="text-align:right" | 40 | style="text-align:right" | 57 | 96.91096380(13) | 16.749(8)&nbsp;h | β^− | ^97mNb | 1/2+ | | |-id=Zirconium-97m | style="text-indent:1em" | ^97mZr | colspan="3" style="text-indent:2em" | 1264.35(16)&nbsp;keV | 104.8(17)&nbsp;ns | IT | ⁹⁷Zr | 7/2+ | | |-id=Zirconium-98 | ⁹⁸Zr | style="text-align:right" | 40 | style="text-align:right" | 58 | 97.9127404(91) | 30.7(4)&nbsp;s | β^− | ⁹⁸Nb | 0+ | | |-id=Zirconium-98m | style="text-indent:1em" | ^98mZr | colspan="3" style="text-indent:2em" | 6601.9(11)&nbsp;keV | 1.9(2)&nbsp;μs | IT | ⁹⁸Zr | (17−) | | |-id=Zirconium-99 | ⁹⁹Zr | style="text-align:right" | 40 | style="text-align:right" | 59 | 98.916675(11) | 2.1(1)&nbsp;s | β^− | ^99mNb | 1/2+ | | |-id=Zirconium-99m | style="text-indent:1em" | ^99mZr | colspan="3" style="text-indent:2em" | 251.96(9)&nbsp;keV | 336(5)&nbsp;ns | IT | ⁹⁹Zr | 7/2+ | | |-id=Zirconium-100 | ¹⁰⁰Zr | style="text-align:right" | 40 | style="text-align:right" | 60 | 99.9180105(87) | 7.1(4)&nbsp;s | β^− | ¹⁰⁰Nb | 0+ | | |-id=Zirconium-101 | ¹⁰¹Zr | style="text-align:right" | 40 | style="text-align:right" | 61 | 100.9214585(89) | 2.29(8)&nbsp;s | β^− | ¹⁰¹Nb | 3/2+ | | |-id=Zirconium-102 | ¹⁰²Zr | style="text-align:right" | 40 | style="text-align:right" | 62 | 101.9231542(94) | 2.01(8)&nbsp;s | β^− | ¹⁰²Nb | 0+ | | |-id=Zirconium-103 | rowspan=2|¹⁰³Zr | rowspan=2 style="text-align:right" | 40 | rowspan=2 style="text-align:right" | 63 | rowspan=2|102.9272041(99) | rowspan=2|1.38(7)&nbsp;s | β^− (>99%) | ¹⁰³Nb | rowspan=2|(5/2−) | rowspan=2| | rowspan=2| |- | β^−, n (<1%) | ¹⁰²Nb |-id=Zirconium-104 | rowspan=2|¹⁰⁴Zr | rowspan=2 style="text-align:right" | 40 | rowspan=2 style="text-align:right" | 64 | rowspan=2|103.929449(10) | rowspan=2|920(28)&nbsp;ms | β^− (>99%) | ¹⁰⁴Nb | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β^−, n (<1%) | ¹⁰³Nb |-id=Zirconium-105 | rowspan=2|¹⁰⁵Zr | rowspan=2 style="text-align:right" | 40 | rowspan=2 style="text-align:right" | 65 | rowspan=2|104.934022(13) | rowspan=2|670(28)&nbsp;ms | β^− (>98%) | ¹⁰⁵Nb | rowspan=2|1/2+# | rowspan=2| | rowspan=2| |- | β^−, n (<2%) | ¹⁰⁴Nb |-id=Zirconium-106 | rowspan=2|¹⁰⁶Zr | rowspan=2 style="text-align:right" | 40 | rowspan=2 style="text-align:right" | 66 | rowspan=2|105.93693(22)# | rowspan=2|179(6)&nbsp;ms | β^− (>98%) | ¹⁰⁶Nb | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β^−, n (<2%) | ¹⁰⁵Nb |-id=Zirconium-107 | rowspan=2|¹⁰⁷Zr | rowspan=2 style="text-align:right" | 40 | rowspan=2 style="text-align:right" | 67 | rowspan=2|106.94201(32)# | rowspan=2|145.7(24)&nbsp;ms | β^− (>77%) | ¹⁰⁷Nb | rowspan=2|5/2+# | rowspan=2| | rowspan=2| |- | β^−, n (<23%) | ¹⁰⁶Nb |-id=Zirconium-108 | ¹⁰⁸Zr | style="text-align:right" | 40 | style="text-align:right" | 68 | 107.94530(43)# | 78.5(20)&nbsp;ms | β^− | ¹⁰⁸Nb | 0+ | | |-id=Zirconium-108m | style="text-indent:1em" | ^108mZr | colspan="3" style="text-indent:2em" | 2074.5(8)&nbsp;keV | 540(30)&nbsp;ns | IT | ¹⁰⁸Zr | (6+) | | |-id=Zirconium-109 | ¹⁰⁹Zr | style="text-align:right" | 40 | style="text-align:right" | 69 | 108.95091(54)# | 56(3)&nbsp;ms | β^− | ¹⁰⁹Nb | 5/2+# | | |-id=Zirconium-110 | ¹¹⁰Zr | style="text-align:right" | 40 | style="text-align:right" | 70 | 109.95468(54)# | 37.5(20)&nbsp;ms | β^− | ¹¹⁰Nb | 0+ | | |-id=Zirconium-111 | ¹¹¹Zr | style="text-align:right" | 40 | style="text-align:right" | 71 | 110.96084(64)# | 24.0(5)&nbsp;ms | β^− | ¹¹¹Nb | 5/2+# | | |-id=Zirconium-112 | ¹¹²Zr | style="text-align:right" | 40 | style="text-align:right" | 72 | 111.96520(75)# | 43(21)&nbsp;ms | β^− | ¹¹²Nb | 0+ | | |-id=Zirconium-113 | ¹¹³Zr | style="text-align:right" | 40 | style="text-align:right" | 73 | 112.97172(32)# | 15#&nbsp;ms<br />[>550&nbsp;ns] | | | 3/2+ | | |-id=Zirconium-114 | ¹¹⁴Zr | style="text-align:right" | 40 | style="text-align:right" | 74 | | | | | 0+ | |

Zirconium-88

⁸⁸Zr is a radioisotope of zirconium with a half-life of 83.4 days. In January 2019, this isotope was discovered to have a thermal neutron capture cross section of approximately 861,000 barns; this is several orders of magnitude greater than predicted, and greater than that of any other nuclide except xenon-135.

Zirconium-89

⁸⁹Zr is a radioisotope of zirconium with a half-life of 78.36 hours, produced by proton irradiation of natural yttrium (⁸⁹Y). Its most prominent gamma photon (99% of decays) has an energy of 909&nbsp;keV and it emits a positron (as opposed to electron capture) about 23% of decays. Zirconium-89 is employed in specialized diagnostic applications using positron emission tomography imaging, for example, with zirconium-89 labeled antibodies (immuno-PET).

Zirconium-93

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⁹³Zr is a radioisotope of zirconium with a half-life of 1.61 million years, decaying through emission of a low-energy beta particle. 73% of decays populate an excited state of niobium-93, which decays with a half-life of 13.9 years (almost entirely by internal conversion, emitting no gamma ray) to the stable ground state of ⁹³Nb, while the remaining 27% of decays directly populate the ground state. It is one of the 7 long-lived fission products. The low specific activity and low energy of its radiation limit the radioactive hazards of this isotope, and its insolubility makes it unlikely to escape a waste repository; all these are shared with palladium-107.

Nuclear fission produces it at a fission yield of 6.3% (thermal neutron fission of ²³⁵U), one of the most abundant fission products. Nuclear reactors usually contain large amounts of zirconium as fuel rod cladding (see zircalloy), and neutron irradiation of ⁹²Zr also produces some ⁹³Zr, though this is limited by ⁹²Zr's low neutron capture cross section of 0.22 barns. Indeed, one of the primary reasons for using zirconium in fuel rod cladding is its low cross section.

⁹³Zr also has a low neutron capture cross section of 0.7 barns. Most fission zirconium consists of other isotopes; the other isotope with a significant neutron absorption cross section is ⁹¹Zr with a cross section of 1.24 barns. ⁹³Zr is a less attractive candidate for disposal by nuclear transmutation than are ⁹⁹Tc and ¹²⁹I. The isotope could be recycled: if the effect on the neutron economy of 's higher cross section is deemed acceptable, irradiated cladding and fission product zirconium (which are mixed together in most current nuclear reprocessing methods) could be used to form new zircalloy cladding. Once the cladding is inside the reactor, the relatively low level radioactivity can be tolerated, but transport and manufacturing might require precautions not now taken.

See also

Daughter products other than zirconium

• Isotopes of molybdenum
• Isotopes of niobium
• Isotopes of yttrium
• Isotopes of strontium

References