# Isotopes of zirconium

Naturally occurring zirconium ($_{40}$Zr) is composed of four stable isotopes (of which one may in the future be found radioactive), and one very long-lived radioisotope ($^{96}$Zr), a primordial nuclide that decays via double beta decay with an observed half-life of 2.0×10$^{19}$ years; it can also undergo single beta decay, which is not yet observed, but the theoretically predicted value of t$_{1/2}$ is 2.4×10$^{20}$ years. The second most stable radioisotope is $^{93}$Zr, which has a half-life of 1.53 million years. Thirty other radioisotopes have been observed. All have half-lives less than a day except for $^{95}$Zr (64.02 days), $^{88}$Zr (83.4 days), and $^{89}$Zr (78.41 hours). The primary decay mode is electron capture for isotopes lighter than $^{92}$Zr, and the primary mode for heavier isotopes is beta decay.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{77}$Zr | 40 | 37 | 76.96608(43)# | 100# μs | | | 3/2−# | | |
| $^{78}$Zr | 40 | 38 | 77.95615(43)# | 50# ms [>200 ns] | | | 0+ | | |
| $^{79}$Zr | 40 | 39 | 78.94979(32)# | 56(30) ms | β$^+$ | $^{79}$Y | 5/2+# | | |
| $^{80}$Zr | 40 | 40 | 79.94121(32)# | 4.6(6) s | β$^+$ | $^{80}$Y | 0+ | | |
| $^{81}$Zr | 40 | 41 | 80.938245(99) | 5.5(4) s | β$^+$ (99.88%) | $^{81}$Y | (3/2−) | | |
| $^{81}$Zr | 40 | 41 | 80.938245(99) | 5.5(4) s | β$^+$, p (0.12%) | $^{80}$Sr | (3/2−) | | |
| $^{82}$Zr | 40 | 42 | 81.9317075(17) | 32(5) s | β$^+$ | $^{82}$Y | 0+ | | |
| $^{83}$Zr | 40 | 43 | 82.9292409(69) | 42(2) s | β$^+$ | $^{83}$Y | 1/2−# | | |
| $^{83}$Zr | 40 | 43 | 82.9292409(69) | 42(2) s | β$^+$, p (?%) | $^{82}$Sr | 1/2−# | | |
| $^{83m1}$Zr | 52.72(5) keV | 52.72(5) keV | 52.72(5) keV | 0.53(12) μs | IT | $^{83}$Zr | (5/2−) | | |
| $^{83m2}$Zr | 77.04(7) keV | 77.04(7) keV | 77.04(7) keV | 1.8(1) μs | IT | $^{83}$Zr | (7/2+) | | |
| $^{84}$Zr | 40 | 44 | 83.9233257(59) | 25.8(5) min | β$^+$ | $^{84}$Y | 0+ | | |
| $^{85}$Zr | 40 | 45 | 84.9214432(69) | 7.86(4) min | β$^+$ | $^{85}$Y | (7/2+) | | |
| $^{85m}$Zr | 292.2(3) keV | 292.2(3) keV | 292.2(3) keV | 10.9(3) s | IT (?%) | $^{85}$Zr | 1/2−# | | |
| $^{85m}$Zr | 292.2(3) keV | 292.2(3) keV | 292.2(3) keV | 10.9(3) s | β$^+$ (?%) | $^{85}$Y | 1/2−# | | |
| $^{86}$Zr | 40 | 46 | 85.9162968(38) | 16.5(1) h | β$^+$ | $^{86}$Y | 0+ | | |
| $^{87}$Zr | 40 | 47 | 86.9148173(45) | 1.68(1) h | β$^+$ | $^{87}$Y | 9/2+ | | |
| $^{87m}$Zr | 335.84(19) keV | 335.84(19) keV | 335.84(19) keV | 14.0(2) s | IT | $^{87}$Zr | 1/2− | | |
| $^{88}$Zr | 40 | 48 | 87.9102207(58) | 83.4(3) d | EC | $^{88}$Y | 0+ | | |
| $^{88m}$Zr | 2887.79(6) keV | 2887.79(6) keV | 2887.79(6) keV | 1.320(25) μs | IT | $^{88}$Zr | 8+ | | |
| $^{89}$Zr | 40 | 49 | 88.9088798(30) | 78.360(23) h | β$^+$ | $^{89}$Y | 9/2+ | | |
| $^{89m}$Zr | 587.82(10) keV | 587.82(10) keV | 587.82(10) keV | 4.161(10) min | IT (93.77%) | $^{89}$Zr | 1/2− | | |
| $^{89m}$Zr | 587.82(10) keV | 587.82(10) keV | 587.82(10) keV | 4.161(10) min | β$^+$ (6.23%) | $^{89}$Y | 1/2− | | |
| $^{90}$Zr | 40 | 50 | 89.90469876(13) | Stable | Stable | Stable | 0+ | 0.5145(4) | |
| $^{90m1}$Zr | 2319.000(9) keV | 2319.000(9) keV | 2319.000(9) keV | 809.2(20) ms | IT | $^{90}$Zr | 5- | | |
| $^{90m2}$Zr | 3589.418(15) keV | 3589.418(15) keV | 3589.418(15) keV | 131(4) ns | IT | $^{90}$Zr | 8+ | | |
| $^{91}$Zr | 40 | 51 | 90.90564021(10) | Stable | Stable | Stable | 5/2+ | 0.1122(5) | |
| $^{91m}$Zr | 3167.3(4) keV | 3167.3(4) keV | 3167.3(4) keV | 4.35(14) μs | IT | $^{91}$Zr | (21/2+) | | |
| $^{92}$Zr | 40 | 52 | 91.90503534(10) | Stable | Stable | Stable | 0+ | 0.1715(3) | |
| $^{93}$Zr | 40 | 53 | 92.90647066(49) | 1.61(5)×10$^6$ y | β$^−$ (73%) | $^{93m1}$Nb | 5/2+ | | |
| $^{93}$Zr | 40 | 53 | 92.90647066(49) | 1.61(5)×10$^6$ y | β$^−$ (27%) | $^{93}$Nb | 5/2+ | | |
| $^{94}$Zr | 40 | 54 | 93.90631252(18) | Observationally stable | Observationally stable | Observationally stable | 0+ | 0.1738(4) | |
| $^{95}$Zr | 40 | 55 | 94.90804028(93) | 64.032(6) d | β$^−$ | $^{95}$Nb | 5/2+ | | |
| $^{96}$Zr | 40 | 56 | 95.90827762(12) | 2.34(17)×10$^{19}$ y | β$^−$β$^−$ | $^{96}$Mo | 0+ | 0.0280(2) | |
| $^{97}$Zr | 40 | 57 | 96.91096380(13) | 16.749(8) h | β$^−$ | $^{97m}$Nb | 1/2+ | | |
| $^{97m}$Zr | 1264.35(16) keV | 1264.35(16) keV | 1264.35(16) keV | 104.8(17) ns | IT | $^{97}$Zr | 7/2+ | | |
| $^{98}$Zr | 40 | 58 | 97.9127404(91) | 30.7(4) s | β$^−$ | $^{98}$Nb | 0+ | | |
| $^{98m}$Zr | 6601.9(11) keV | 6601.9(11) keV | 6601.9(11) keV | 1.9(2) μs | IT | $^{98}$Zr | (17−) | | |
| $^{99}$Zr | 40 | 59 | 98.916675(11) | 2.1(1) s | β$^−$ | $^{99m}$Nb | 1/2+ | | |
| $^{99m}$Zr | 251.96(9) keV | 251.96(9) keV | 251.96(9) keV | 336(5) ns | IT | $^{99}$Zr | 7/2+ | | |
| $^{100}$Zr | 40 | 60 | 99.9180105(87) | 7.1(4) s | β$^−$ | $^{100}$Nb | 0+ | | |
| $^{101}$Zr | 40 | 61 | 100.9214585(89) | 2.29(8) s | β$^−$ | $^{101}$Nb | 3/2+ | | |
| $^{102}$Zr | 40 | 62 | 101.9231542(94) | 2.01(8) s | β$^−$ | $^{102}$Nb | 0+ | | |
| $^{103}$Zr | 40 | 63 | 102.9272041(99) | 1.38(7) s | β$^−$ (>99%) | $^{103}$Nb | (5/2−) | | |
| $^{103}$Zr | 40 | 63 | 102.9272041(99) | 1.38(7) s | β$^−$, n (<1%) | $^{102}$Nb | (5/2−) | | |
| $^{104}$Zr | 40 | 64 | 103.929449(10) | 920(28) ms | β$^−$ (>99%) | $^{104}$Nb | 0+ | | |
| $^{104}$Zr | 40 | 64 | 103.929449(10) | 920(28) ms | β$^−$, n (<1%) | $^{103}$Nb | 0+ | | |
| $^{105}$Zr | 40 | 65 | 104.934022(13) | 670(28) ms | β$^−$ (>98%) | $^{105}$Nb | 1/2+# | | |
| $^{105}$Zr | 40 | 65 | 104.934022(13) | 670(28) ms | β$^−$, n (<2%) | $^{104}$Nb | 1/2+# | | |
| $^{106}$Zr | 40 | 66 | 105.93693(22)# | 179(6) ms | β$^−$ (>98%) | $^{106}$Nb | 0+ | | |
| $^{106}$Zr | 40 | 66 | 105.93693(22)# | 179(6) ms | β$^−$, n (<2%) | $^{105}$Nb | 0+ | | |
| $^{107}$Zr | 40 | 67 | 106.94201(32)# | 145.7(24) ms | β$^−$ (>77%) | $^{107}$Nb | 5/2+# | | |
| $^{107}$Zr | 40 | 67 | 106.94201(32)# | 145.7(24) ms | β$^−$, n (<23%) | $^{106}$Nb | 5/2+# | | |
| $^{108}$Zr | 40 | 68 | 107.94530(43)# | 78.5(20) ms | β$^−$ | $^{108}$Nb | 0+ | | |
| $^{108m}$Zr | 2074.5(8) keV | 2074.5(8) keV | 2074.5(8) keV | 540(30) ns | IT | $^{108}$Zr | (6+) | | |
| $^{109}$Zr | 40 | 69 | 108.95091(54)# | 56(3) ms | β$^−$ | $^{109}$Nb | 5/2+# | | |
| $^{110}$Zr | 40 | 70 | 109.95468(54)# | 37.5(20) ms | β$^−$ | $^{110}$Nb | 0+ | | |
| $^{111}$Zr | 40 | 71 | 110.96084(64)# | 24.0(5) ms | β$^−$ | $^{111}$Nb | 5/2+# | | |
| $^{112}$Zr | 40 | 72 | 111.96520(75)# | 43(21) ms | β$^−$ | $^{112}$Nb | 0+ | | |
| $^{113}$Zr | 40 | 73 | 112.97172(32)# | 15# ms [>550 ns] | | | 3/2+ | | |
| $^{114}$Zr | 40 | 74 | | | | | 0+ | | |
| This table header & footer: view ||||||||||
* ↑ $^m$Zr – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* ↑ Bold half-life – nearly stable, half-life longer than age of universe.
* 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ Second most powerful known neutron absorber
* 1 2 3 4 5 6 Fission product
* ↑ Long-lived fission product
* ↑ Believed to decay by β$^−$β$^−$ to $^{94}$Mo with a half-life over 1.1×10$^{17}$ years
* ↑ Primordial radionuclide
* ↑ Predicted to be capable of undergoing triple beta decay and quadruple beta decay with very long partial half-lives
* ↑ Theorized to also undergo β$^−$ decay to $^{96}$Nb with a partial half-life greater than 2.4×10$^{19}$ y

## Zirconium-88

$^{88}$Zr is a radioisotope of zirconium with a half-life of 83.4 days. In January 2019, this isotope was discovered to have a 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

$^{89}$Zr is a radioisotope of zirconium with a half-life of 78.41 hours. It is produced by proton irradiation of natural yttrium-89. Its most prominent gamma photon has an energy of 909 keV.
Zirconium-89 is employed in specialized diagnostic applications using positron emission tomography imaging, for example, with zirconium-89 labeled antibodies (immuno-PET). For a decay table, see Maria Vosjan. "Zirconium-89 ($^{89}$Zr)". Cyclotron.nl.

## Zirconium-93

Yield, % per fission :
| | Thermal | Fast | 14 MeV |
| $^{232}$Th | not fissile | 6.70 ± 0.40 | 5.58 ± 0.16 |
| $^{233}$U | 6.979 ± 0.098 | 6.94 ± 0.07 | 5.38 ± 0.32 |
| $^{235}$U | 6.346 ± 0.044 | 6.25 ± 0.04 | 5.19 ± 0.31 |
| $^{238}$U | not fissile | 4.913 ± 0.098 | 4.53 ± 0.13 |
| $^{239}$Pu | 3.80 ± 0.03 | 3.82 ± 0.03 | 3.0 ± 0.3 |
| $^{241}$Pu | 2.98 ± 0.04 | 2.98 ± 0.33 | ? |
Long-lived fission productsvte :
| Nuclide | t$_{1⁄2}$ | Yield | Q | βγ |
| | (Ma) | (%) | (keV) | |
| $^{99}$Tc | 0.211 | 6.1385 | 294 | β |
| $^{126}$Sn | 0.230 | 0.1084 | 4050 | βγ |
| $^{79}$Se | 0.327 | 0.0447 | 151 | β |
| $^{135}$Cs | 1.33 | 6.9110 | 269 | β |
| $^{93}$Zr | 1.53 | 5.4575 | 91 | βγ |
| $^{107}$Pd | 6.5 | 1.2499 | 33 | β |
| $^{129}$I | 16.14 | 0.8410 | 194 | βγ |
| ↑ Decay energy is split among β, neutrino, and γ if any. ↑ Per 65 thermal neutron fissions of $^{235}$U and 35 of $^{239}$Pu. ↑ Has decay energy 380 keV, but its decay product $^{126}$Sb has decay energy 3.67 MeV. ↑ Lower in thermal reactors because $^{135}$Xe, its predecessor, readily absorbs neutrons. |||||
$^{93}$Zr is a radioisotope of zirconium with a half-life of 1.53 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 14 years and a low-energy gamma ray to the stable ground state of $^{93}$Nb, while the remaining 27% of decays directly populate the ground state. It is one of only 7 long-lived fission products. The low specific activity and low energy of its radiations limit the radioactive hazards of this isotope.
Nuclear fission produces it at a fission yield of 6.3% (thermal neutron fission of $^{235}$U), on a par with the other most abundant fission products. Nuclear reactors usually contain large amounts of zirconium as fuel rod cladding (see zircaloy), and neutron irradiation of $^{92}$Zr also produces some $^{93}$Zr, though this is limited by $^{92}$Zr'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.
$^{93}$Zr 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 $^{91}$Zr with a cross section of 1.24 barns. $^{93}$Zr is a less attractive candidate for disposal by nuclear transmutation than are $^{99}$Tc and $^{129}$I. Mobility in soil is relatively low, so that geological disposal may be an adequate solution. Alternatively, if the effect on the neutron economy of $^{93}$ Zr'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 special precautions.