Naturally occurring

zirconium Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'', ...

(₄₀Zr) is composed of four stable

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

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 nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

(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 clos ...

with an observed

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...

of 2.0×10¹⁹ years; it can also undergo single

beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For ...

, 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 1.53 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. Thi ...

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

List of isotopes

, - , ⁷⁸Zr , style="text-align:right" , 40 , style="text-align:right" , 38 , 77.95523(54)# , 50# ms
170 ns, , , 0+ , , , - , rowspan=2, ⁷⁹Zr , rowspan=2 style="text-align:right" , 40 , rowspan=2 style="text-align:right" , 39 , rowspan=2, 78.94916(43)# , rowspan=2, 56(30) ms , β⁺, p , ⁷⁸Sr , rowspan=2, 5/2+# , rowspan=2, , rowspan=2, , - , β⁺ , ⁷⁹Y , - , ⁸⁰Zr , style="text-align:right" , 40 , style="text-align:right" , 40 , 79.9404(16) , 4.6(6) s , β⁺ , ⁸⁰Y , 0+ , , , - , rowspan=2, ⁸¹Zr , rowspan=2 style="text-align:right" , 40 , rowspan=2 style="text-align:right" , 41 , rowspan=2, 80.93721(18) , rowspan=2, 5.5(4) s , β⁺ (>99.9%) , ⁸¹Y , rowspan=2, (3/2−)# , rowspan=2, , rowspan=2, , - , β⁺, p (<.1%) , ⁸⁰Sr , - , ⁸²Zr , style="text-align:right" , 40 , style="text-align:right" , 42 , 81.93109(24)# , 32(5) s , β⁺ , ⁸²Y , 0+ , , , - , rowspan=2, ⁸³Zr , rowspan=2 style="text-align:right" , 40 , rowspan=2 style="text-align:right" , 43 , rowspan=2, 82.92865(10) , rowspan=2, 41.6(24) s , β⁺ (>99.9%) , ⁸³Y , rowspan=2, (1/2−)# , rowspan=2, , rowspan=2, , - , β⁺, p (<.1%) , ⁸²Sr , - , ⁸⁴Zr , style="text-align:right" , 40 , style="text-align:right" , 44 , 83.92325(21)# , 25.9(7) min , β⁺ , ⁸⁴Y , 0+ , , , - , ⁸⁵Zr , style="text-align:right" , 40 , style="text-align:right" , 45 , 84.92147(11) , 7.86(4) min , β⁺ , ⁸⁵Y , 7/2+ , , , - , 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 (92%) , ⁸⁵Zr , rowspan=2, (1/2−) , rowspan=2, , rowspan=2, , - , β⁺ (8%) , ⁸⁵Y , - , ⁸⁶Zr , style="text-align:right" , 40 , style="text-align:right" , 46 , 85.91647(3) , 16.5(1) h , β⁺ , ⁸⁶Y , 0+ , , , - , ⁸⁷Zr , style="text-align:right" , 40 , style="text-align:right" , 47 , 86.914816(9) , 1.68(1) h , β⁺ , ⁸⁷Y , (9/2)+ , , , - , 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 eff ...

, style="text-align:right" , 40 , style="text-align:right" , 48 , 87.910227(11) , 83.4(3) d , EC , ⁸⁸Y , 0+ , , , - , ⁸⁹Zr , style="text-align:right" , 40 , style="text-align:right" , 49 , 88.908890(4) , 78.41(12) h , β⁺ , ⁸⁹Y , 9/2+ , , , - , rowspan=2 style="text-indent:1em" , ^89mZr , rowspan=2 colspan="3" style="text-indent:2em" , 587.82(10) keV , rowspan=2, 4.161(17) min , IT (93.77%) , ⁸⁹Zr , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , β⁺ (6.23%) , ⁸⁹Y , - , 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 release ...

, style="text-align:right" , 40 , style="text-align:right" , 50 , 89.9047044(25) , colspan=3 align=center, Stable , 0+ , 0.5145(40) , , - , style="text-indent:1em" , ^90m1Zr , colspan="3" style="text-indent:2em" , 2319.000(10) keV , 809.2(20) ms , IT , ⁹⁰Zr , 5- , , , - , style="text-indent:1em" , ^90m2Zr , colspan="3" style="text-indent:2em" , 3589.419(16) keV , 131(4) ns , , , 8+ , , , - , ⁹¹Zr , style="text-align:right" , 40 , style="text-align:right" , 51 , 90.9056458(25) , colspan=3 align=center, Stable , 5/2+ , 0.1122(5) , , - , style="text-indent:1em" , ^91mZr , colspan="3" style="text-indent:2em" , 3167.3(4) keV , 4.35(14) μs , , , (21/2+) , , , - , ⁹²Zr , style="text-align:right" , 40 , style="text-align:right" , 52 , 91.9050408(25) , colspan=3 align=center, Stable , 0+ , 0.1715(8) , , - , 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 man ...

, rowspan=2 style="text-align:right" , 40 , rowspan=2 style="text-align:right" , 53 , rowspan=2 , 92.9064760(25) , rowspan=2 , 1.53(10)×10⁶ y , β⁻ (73%) , ^93mNb , rowspan=2 , 5/2+ , rowspan=2 , , rowspan=2 , , - , β⁻ (27%) , ⁹³Nb , - , ⁹⁴Zr , style="text-align:right" , 40 , style="text-align:right" , 54 , 93.9063152(26) , colspan=3 align=center,

Observationally stable Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes. Th ...

Believed to decay by β⁻β⁻ to ⁹⁴Mo with a half-life over 1.1×10¹⁷ years , 0+ , 0.1738(28) , , - , ⁹⁵Zr , style="text-align:right" , 40 , style="text-align:right" , 55 , 94.9080426(26) , 64.032(6) d , β⁻ , ⁹⁵Nb , 5/2+ , , , - , ⁹⁶Zr Primordial

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...

, style="text-align:right" , 40 , style="text-align:right" , 56 , 95.9082734(30) , 20(4)×10¹⁸ y , β⁻β⁻ , ⁹⁶Mo , 0+ , 0.0280(9) , , - , ⁹⁷Zr , style="text-align:right" , 40 , style="text-align:right" , 57 , 96.9109531(30) , 16.744(11) h , β⁻ , ^97mNb , 1/2+ , , , - , ⁹⁸Zr , style="text-align:right" , 40 , style="text-align:right" , 58 , 97.912735(21) , 30.7(4) s , β⁻ , ⁹⁸Nb , 0+ , , , - , ⁹⁹Zr , style="text-align:right" , 40 , style="text-align:right" , 59 , 98.916512(22) , 2.1(1) s , β⁻ , ^99mNb , 1/2+ , , , - , ¹⁰⁰Zr , style="text-align:right" , 40 , style="text-align:right" , 60 , 99.91776(4) , 7.1(4) s , β⁻ , ¹⁰⁰Nb , 0+ , , , - , ¹⁰¹Zr , style="text-align:right" , 40 , style="text-align:right" , 61 , 100.92114(3) , 2.3(1) s , β⁻ , ¹⁰¹Nb , 3/2+ , , , - , ¹⁰²Zr , style="text-align:right" , 40 , style="text-align:right" , 62 , 101.92298(5) , 2.9(2) s , β⁻ , ¹⁰²Nb , 0+ , , , - , ¹⁰³Zr , style="text-align:right" , 40 , style="text-align:right" , 63 , 102.92660(12) , 1.3(1) s , β⁻ , ¹⁰³Nb , (5/2−) , , , - , ¹⁰⁴Zr , style="text-align:right" , 40 , style="text-align:right" , 64 , 103.92878(43)# , 1.2(3) s , β⁻ , ¹⁰⁴Nb , 0+ , , , - , rowspan=2, ¹⁰⁵Zr , rowspan=2 style="text-align:right" , 40 , rowspan=2 style="text-align:right" , 65 , rowspan=2, 104.93305(43)# , rowspan=2, 0.6(1) s , β⁻ (>99.9%) , ¹⁰⁵Nb , rowspan=2, , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ¹⁰⁴Nb , - , ¹⁰⁶Zr , style="text-align:right" , 40 , style="text-align:right" , 66 , 105.93591(54)# , 200# ms
300 ns, β⁻ , ¹⁰⁶Nb , 0+ , , , - , ¹⁰⁷Zr , style="text-align:right" , 40 , style="text-align:right" , 67 , 106.94075(32)# , 150# ms
300 ns, β⁻ , ¹⁰⁷Nb , , , , - , ¹⁰⁸Zr , style="text-align:right" , 40 , style="text-align:right" , 68 , 107.94396(64)# , 80# ms
300 ns, β⁻ , ¹⁰⁸Nb , 0+ , , , - , ¹⁰⁹Zr , style="text-align:right" , 40 , style="text-align:right" , 69 , 108.94924(54)# , 60# ms
300 ns, , , , , , - , ¹¹⁰Zr , style="text-align:right" , 40 , style="text-align:right" , 70 , 109.95287(86)# , 30# ms
300 ns, , , 0+ , , , - , ¹¹¹Zr , style="text-align:right" , 40 , style="text-align:right" , 71 , , , , , , , , - , ¹¹²Zr , style="text-align:right" , 40 , style="text-align:right" , 72 , , , , , 0+ , , , - , ¹¹³Zr , style="text-align:right" , 40 , style="text-align:right" , 73 , , , , , , , , - , 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, ...

cross section Cross section may refer to: * Cross section (geometry) ** Cross-sectional views in architecture & engineering 3D *Cross section (geology) * Cross section (electronics) * Radar cross section, measure of detectability * Cross section (physics) **Abs ...

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 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 (2 million barns; up to 3 million barns under reactor c ...

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 Metabolism, metabolic processes, and in other physiological activities including bl ...

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

Zirconium-93

⁹³Zr is a

with a

of 1.53 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 during the process of beta decay. There are two forms of beta decay, β� ...

. 73% of decays populate an

excited state In quantum mechanics, an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). Excitation refers to a ...

niobium Niobium is a chemical element with chemical symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and it has sim ...

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

gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...

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 man ...

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 radio ...

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 is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission. Most nuclear fuels contain heavy fissile actinide elements that are capable of undergoing ...

cladding Cladding is an outer layer of material covering another. It may refer to the following: *Cladding (boiler), the layer of insulation and outer wrapping around a boiler shell *Cladding (construction), materials applied to the exterior of buildings ...

(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 cross-section of thermal neutrons, high hardness, ductility and corrosion resistance. One of the ...

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

of 0.22

barns A barn is an agricultural building usually on farms and used for various purposes. In North America, a barn refers to structures that house livestock, including cattle and horses, as well as equipment and fodder, and often grain.Allen G. ...

. Indeed one of the primary reasons for using zirconium in fuel rod cladding is its low cross section. ⁹³Zr also has a low

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 transmutatio ...

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 Neutron economy is defined as the ratio of an adjoint weighted average of the excess neutron production divided by an adjoint weighted average of the fission production. The distribution of neutron energies in a nuclear reactor differs from the f ...

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 with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'', ...