Naturally occurring

zirconium Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyis ...

(₄₀Zr) is composed of four stable

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

s (of which one may in the future be found radioactive), and one very long-lived

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

(⁹⁶Zr), a

primordial nuclide In geochemistry, geophysics and nuclear physics, primordial nuclides, also known as primordial isotopes, are nuclides found on Earth that have existed in their current form since before Earth was formed. Primordial nuclides were present in the ...

that decays via

double beta decay In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa, inside an atomic nucleus. As in single beta decay, this process allows the atom to move cl ...

with an observed

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

of 2.34 × 10¹⁹ years; it can also undergo single

beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which an atomic nucleus emits a beta particle (fast energetic electron or positron), transforming into an isobar of that nuclide. For example, beta decay of a neutron ...

, 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. All have half-lives less than a day except for ⁹⁵Zr (64.02 days), ⁸⁸Zr (83.4 days), and ⁸⁹Zr (78.41 hours). The primary decay mode is

electron capture Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Th ...

for isotopes lighter than ⁹²Zr, and the primary mode for heavier isotopes is beta decay.

List of isotopes

, -id=Zirconium-77 , ⁷⁷Zr , style="text-align:right" , 40 , style="text-align:right" , 37 , 76.96608(43)# , 100# μs , , , 3/2−# , , , -id=Zirconium-78 , ⁷⁸Zr , style="text-align:right" , 40 , style="text-align:right" , 38 , 77.95615(43)# , 50# ms
200 ns, , , 0+ , , , -id=Zirconium-79 , ⁷⁹Zr , style="text-align:right" , 40 , style="text-align:right" , 39 , 78.94979(32)# , 56(30) ms , β⁺ , ⁷⁹Y , 5/2+# , , , -id=Zirconium-80 , ⁸⁰Zr , style="text-align:right" , 40 , style="text-align:right" , 40 , 79.94121(32)# , 4.6(6) 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, 80.938245(99) , rowspan=2, 5.5(4) 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) 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, 82.9292409(69) , rowspan=2, 42(2) 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) keV , 0.53(12) μs , IT , ⁸³Zr , (5/2−) , , , -id=Zirconium-83m2 , style="text-indent:1em" , ^83m2Zr , colspan="3" style="text-indent:2em" , 77.04(7) keV , 1.8(1) 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) min , β⁺ , ⁸⁴Y , 0+ , , , -id=Zirconium-85 , ⁸⁵Zr , style="text-align:right" , 40 , style="text-align:right" , 45 , 84.9214432(69) , 7.86(4) 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) keV , rowspan=2, 10.9(3) 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) h , β⁺ , ⁸⁶Y , 0+ , , , -id=Zirconium-87 , ⁸⁷Zr , style="text-align:right" , 40 , style="text-align:right" , 47 , 86.9148173(45) , 1.68(1) h , β⁺ , ⁸⁷Y , 9/2+ , , , -id=Zirconium-87m , style="text-indent:1em" , ^87mZr , colspan="3" style="text-indent:2em" , 335.84(19) keV , 14.0(2) s , IT , ⁸⁷Zr , 1/2− , , , - , ⁸⁸ZrSecond most powerful known

neutron absorber In applications such as nuclear reactors, a neutron poison (also called a neutron absorber or a nuclear poison) is a substance with a large neutron absorption cross-section. In such applications, absorbing neutrons is normally an undesirable ef ...

, style="text-align:right" , 40 , style="text-align:right" , 48 , 87.9102207(58) , 83.4(3) d , EC , ⁸⁸Y , 0+ , , , -id=Zirconium-88m , style="text-indent:1em" , ^88mZr , colspan="3" style="text-indent:2em" , 2887.79(6) keV , 1.320(25) μs , IT , ⁸⁸Zr , 8+ , , , - , ⁸⁹Zr , style="text-align:right" , 40 , style="text-align:right" , 49 , 88.9088798(30) , 78.360(23) 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) keV , rowspan=2, 4.161(10) min , IT (93.77%) , ⁸⁹Zr , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , β⁺ (6.23%) , ⁸⁹Y , -id=Zirconium-90 , ⁹⁰Zr

Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the releas ...

, 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) keV , 809.2(20) ms , IT , ⁹⁰Zr , 5- , , , -id=Zirconium-90m2 , style="text-indent:1em" , ^90m2Zr , colspan="3" style="text-indent:2em" , 3589.418(15) keV , 131(4) 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) keV , 4.35(14) 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

Long-lived fission product Long-lived fission products (LLFPs) are radioactive materials with a long half-life (more than 200,000 years) produced by nuclear fission of uranium and plutonium. Because of their persistent radiotoxicity, it is necessary to isolate them from hum ...

, 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 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 Stable nuclides are isotopes of a chemical element whose nucleons are in a configuration that does not permit them the surplus energy required to produce a radioactive emission. The nuclei of such isotopes are not radioactive and unlike radionuc ...

Believed to decay by β⁻β⁻ to ⁹⁴Mo with a half-life over 1.1×10¹⁷ years , 0+ , 0.1738(4) , , -id=Zirconium-95 , ⁹⁵Zr , style="text-align:right" , 40 , style="text-align:right" , 55 , 94.90804028(93) , 64.032(6) d , β⁻ , ⁹⁵Nb , 5/2+ , , , -id=Zirconium-96 , ⁹⁶Zr Primordial

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

, style="text-align:right" , 40 , style="text-align:right" , 56 , 95.90827762(12) , 2.34(17)×10¹⁹ 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) h , β⁻ , ^97mNb , 1/2+ , , , -id=Zirconium-97m , style="text-indent:1em" , ^97mZr , colspan="3" style="text-indent:2em" , 1264.35(16) keV , 104.8(17) 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) s , β⁻ , ⁹⁸Nb , 0+ , , , -id=Zirconium-98m , style="text-indent:1em" , ^98mZr , colspan="3" style="text-indent:2em" , 6601.9(11) keV , 1.9(2) μs , IT , ⁹⁸Zr , (17−) , , , -id=Zirconium-99 , ⁹⁹Zr , style="text-align:right" , 40 , style="text-align:right" , 59 , 98.916675(11) , 2.1(1) s , β⁻ , ^99mNb , 1/2+ , , , -id=Zirconium-99m , style="text-indent:1em" , ^99mZr , colspan="3" style="text-indent:2em" , 251.96(9) keV , 336(5) 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) s , β⁻ , ¹⁰⁰Nb , 0+ , , , -id=Zirconium-101 , ¹⁰¹Zr , style="text-align:right" , 40 , style="text-align:right" , 61 , 100.9214585(89) , 2.29(8) 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) 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) 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) 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) 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) 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) 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) ms , β⁻ , ¹⁰⁸Nb , 0+ , , , -id=Zirconium-108m , style="text-indent:1em" , ^108mZr , colspan="3" style="text-indent:2em" , 2074.5(8) keV , 540(30) ns , IT , ¹⁰⁸Zr , (6+) , , , -id=Zirconium-109 , ¹⁰⁹Zr , style="text-align:right" , 40 , style="text-align:right" , 69 , 108.95091(54)# , 56(3) 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) ms , β⁻ , ¹¹⁰Nb , 0+ , , , -id=Zirconium-111 , ¹¹¹Zr , style="text-align:right" , 40 , style="text-align:right" , 71 , 110.96084(64)# , 24.0(5) ms , β⁻ , ¹¹¹Nb , 5/2+# , , , -id=Zirconium-112 , ¹¹²Zr , style="text-align:right" , 40 , style="text-align:right" , 72 , 111.96520(75)# , 43(21) ms , β⁻ , ¹¹²Nb , 0+ , , , -id=Zirconium-113 , ¹¹³Zr , style="text-align:right" , 40 , style="text-align:right" , 73 , 112.97172(32)# , 15# ms
550 ns, , , 3/2+ , , , -id=Zirconium-114 , ¹¹⁴Zr , style="text-align:right" , 40 , style="text-align:right" , 74 , , , , , 0+ , ,

Zirconium-88

⁸⁸Zr is a

with a half-life of 83.4 days. In January 2019, this isotope was discovered to have a

neutron capture Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, wh ...

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 Xenon-135 (135Xe) is an Isotope#Radioactive, primordial, and stable isotopes, unstable isotope of xenon with a half-life of about 9.2 hours. 135Xe is a fission product of uranium and it is the most powerful known neutron-absorbing nuclear poison ...

Zirconium-89

⁸⁹Zr is a radioisotope of zirconium with a

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 Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, r ...

imaging, for example, with zirconium-89 labeled antibodies (immuno-PET). For a decay table, see

Zirconium-93

⁹³Zr is a

with a

of 1.61 million years, decaying through emission of a low-energy

beta particle A beta particle, also called beta ray or beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus, known as beta decay. There are two forms of beta decay, β− decay and � ...

. 73% of decays populate an

excited state In quantum mechanics Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Add ...

niobium Niobium is a chemical element; it has chemical symbol, symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and Ductility, ductile transition metal. Pure niobium has a Mohs scale of mineral hardness, Mohs h ...

-93, which decays with a half-life of 14 years and a low-energy

gamma ray A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

to the stable ground state of ⁹³Nb, while the remaining 27% of decays directly populate the ground state. It is one of only 7

long-lived fission product Long-lived fission products (LLFPs) are radioactive materials with a long half-life (more than 200,000 years) produced by nuclear fission of uranium and plutonium. Because of their persistent radiotoxicity, it is necessary to isolate them from hum ...

s. The low specific activity and low energy of its radiations limit the radioactive hazards of this isotope.

Nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...

produces it at a fission yield of 6.3% (thermal neutron fission of ²³⁵U), on a par with the other most abundant fission products. Nuclear reactors usually contain large amounts of zirconium as

fuel rod Nuclear fuel refers to any substance, typically fissile material, which is used by nuclear power stations or other nuclear devices to generate energy. Oxide fuel For fission reactors, the fuel (typically based on uranium) is usually based o ...

cladding (see

zircaloy Zirconium alloys are solid solutions of zirconium or other metals, a common subgroup having the trade mark Zircaloy. Zirconium has very low absorption Nuclear cross section, cross-section of thermal neutrons, high hardness, ductility and corrosion ...

), and neutron irradiation of ⁹²Zr also produces some ⁹³Zr, though this is limited by ⁹²Zr's low

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

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 Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. Nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus of an atom is changed. A transmutat ...

than are ⁹⁹Tc and ¹²⁹I. Mobility in soil is relatively low, so that geological disposal may be an adequate solution. Alternatively, 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 Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With commercialization of nuclear power, the ...

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.

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Authority control

Zirconium Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyis ...

List of isotopes

Zirconium-88

Zirconium-89

Zirconium-93

See also

References