Naturally occurring

cobalt Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. ...

, Co, consists of a single 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 ...

, Co (thus, cobalt is a mononuclidic element). Twenty-eight

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 ...

s have been characterized; the most stable are Co with a

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 5.2714 years, Co (271.811 days), Co (77.236 days), and Co (70.844 days). All other isotopes have half-lives of less than 18 hours and most of these have half-lives of less than 1 second. This element also has 19

meta state A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy excited state levels (higher energy levels). "Metastable" describes nuclei whose excited states have half-lives of 10−9 s ...

s, of which the most stable is ^58m1Co with a half-life of 8.853 h. The isotopes of cobalt range in

atomic weight Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a giv ...

from Co to Co. The main

decay mode Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

for isotopes with atomic mass less than that of the stable isotope, Co, 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 ...

and the main mode of decay for those of greater than 59 atomic mass units is

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 ...

. The main

decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( d ...

s before Co are

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

isotopes and the main products after are

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

isotopes. Radioisotopes can be produced by various

nuclear reaction In nuclear physics and nuclear chemistry, a nuclear reaction is a process in which two atomic nucleus, nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a t ...

s. For example, Co is produced by

cyclotron A cyclotron is a type of particle accelerator invented by Ernest Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Januar ...

irradiation of iron. The main reaction is the (d,n) reaction Fe + H → n + Co.

List of isotopes

, -id=Cobalt-50 , rowspan=3, Co , rowspan=3 style="text-align:right" , 27 , rowspan=3 style="text-align:right" , 23 , rowspan=3, 49.98112(14) , rowspan=3, 38.8(2) ms , β, p (70.5%) , Mn , rowspan=3, (6+) , rowspan=3, , - , β (29.5%) , Fe , - , β, 2p? , Cr , -id=Cobalt-51 , rowspan=2, Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 24 , rowspan=2, 50.970647(52) , rowspan=2, 68.8(19) ms , β (96.2%) , Fe , rowspan=2, 7/2− , rowspan=2, , - , β, p (<3.8%) , Mn , -id=Cobalt-52 , rowspan=2, Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 25 , rowspan=2, 51.9631302(57) , rowspan=2, 111.7(21) ms , β , Fe , rowspan=2, 6+ , rowspan=2, , - , β, p? , Mn , -id=Cobalt-52m , rowspan=3 style="text-indent:1em" , Co , rowspan=3 colspan="3" style="text-indent:2em" , 376(9) keV , rowspan=3, 102(5) ms , β , Fe , rowspan=3, 2+ , rowspan=3, , - , IT? , Co , - , β, p? , Mn , -id=Cobalt-53 , Co , style="text-align:right" , 27 , style="text-align:right" , 26 , 52.9542033(19) , 244.6(28) ms , β , Fe , 7/2−# , , -id=Cobalt-53m , rowspan=2 style="text-indent:1em" , Co , rowspan=2 colspan="3" style="text-indent:2em" , 3174.3(9) keV , rowspan=2, 250(10) ms , β? (~98.5%) , Fe , rowspan=2, (19/2−) , rowspan=2, , - , p (~1.5%) , Fe , -id=Cobalt-54 , Co , style="text-align:right" , 27 , style="text-align:right" , 27 , 53.94845908(38) , 193.27(6) ms , β , Fe , 0+ , , -id=Cobalt-54m , style="text-indent:1em" , Co , colspan="3" style="text-indent:2em" , 197.57(10) keV , 1.48(2) min , β , Fe , 7+ , , -id=Cobalt-55 , Co , style="text-align:right" , 27 , style="text-align:right" , 28 , 54.94199642(43) , 17.53(3) h , β , Fe , 7/2− , , -id=Cobalt-56 , Co , style="text-align:right" , 27 , style="text-align:right" , 29 , 55.93983803(51) , 77.236(26) d , β , Fe , 4+ , , - , Co , style="text-align:right" , 27 , style="text-align:right" , 30 , 56.93628982(55) , 271.811(32) d , EC , Fe , 7/2− , , -id=Cobalt-58 , rowspan=2, Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 31 , rowspan=2, 57.9357513(12) , rowspan=2, 70.844(20) d , EC (85.21%) , Fe , rowspan=2, 2+ , rowspan=2, , - , β (14.79%) , Fe , -id=Cobalt-58m1 , rowspan=2 style="text-indent:1em" , Co , rowspan=2 colspan="3" style="text-indent:2em" , 24.95(6) keV , rowspan=2, 8.853(23) h , IT , Co , rowspan=2, 5+ , rowspan=2, , - , EC (0.00120%) , Fe , -id=Cobalt-58m2 , style="text-indent:1em" , Co , colspan="3" style="text-indent:2em" , 53.15(7) keV , 10.5(3) μs , IT , Co , 4+ , , -id=Cobalt-59 , Co , style="text-align:right" , 27 , style="text-align:right" , 32 , 58.93319352(43) , colspan="3" style="text-align:center;", Stable , 7/2− , 1.0000 , - , Co , style="text-align:right" , 27 , style="text-align:right" , 33 , 59.93381554(43) , 5.2714(6) y , β , Ni , 5+ , , -id=Cobalt-60m , rowspan=2 style="text-indent:1em" , Co , rowspan=2 colspan="3" style="text-indent:2em" , 58.59(1) keV , rowspan=2, 10.467(6) min , IT (99.75%) , Co , rowspan=2, 2+ , rowspan=2, , - , β (0.25%) , Ni , -id=Cobalt-61 , Co , style="text-align:right" , 27 , style="text-align:right" , 34 , 60.93247603(90) , 1.649(5) h , β , Ni , 7/2− , , -id=Cobalt-62 , Co , style="text-align:right" , 27 , style="text-align:right" , 35 , 61.934058(20) , 1.54(10) min , β , Ni , (2)+ , , -id=Cobalt-62m , rowspan=2 style="text-indent:1em" , Co , rowspan=2 colspan="3" style="text-indent:2em" , 22(5) keV , rowspan=2, 13.86(9) min , β (>99.5%) , Ni , rowspan=2, (5)+ , rowspan=2, , - , IT (<0.5%) , Co , -id=Cobalt-63 , Co , style="text-align:right" , 27 , style="text-align:right" , 36 , 62.933600(20) , 26.9(4) s , β , Ni , 7/2− , , -id=Cobalt-64 , Co , style="text-align:right" , 27 , style="text-align:right" , 37 , 63.935810(21) , 300(30) ms , β , Ni , 1+ , , -id=Cobalt-64m , rowspan=2 style="text-indent:1em" , Co , rowspan=2 colspan="3" style="text-indent:2em" , 107(20) keV , rowspan=2, 300# ms , β? , Ni , rowspan=2, 5+# , rowspan=2, , - , IT? , Co , -id=Cobalt-65 , Co , style="text-align:right" , 27 , style="text-align:right" , 38 , 64.9364621(22) , 1.16(3) s , β , Ni , (7/2)− , , -id=Cobalt-66 , rowspan=2, Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 39 , rowspan=2, 65.939443(15) , rowspan=2, 194(17) ms , β , Ni , rowspan=2, (1+) , rowspan=2, , - , β, n? , Ni , -id=Cobalt-66m1 , style="text-indent:1em" , Co , colspan="3" style="text-indent:2em" , 175.1(3) keV , 824(22) ns , IT , ⁶⁶Co , (3+) , , -id=Cobalt-66m2 , style="text-indent:1em" , Co , colspan="3" style="text-indent:2em" , 642(5) keV , >100 μs , IT , ⁶⁶Co , (8−) , , -id=Cobalt-67 , rowspan=2, Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 40 , rowspan=2, 66.9406096(69) , rowspan=2, 329(28) ms , β , Ni , rowspan=2, (7/2−) , rowspan=2, , - , β, n? , Ni , -id=Cobalt-67m , rowspan=2 style="text-indent:1em" , Co , rowspan=2 colspan="3" style="text-indent:2em" , 491.55(11) keV , rowspan=2, 496(33) ms , IT (>80%) , ⁶⁷Co , rowspan=2, (1/2−) , rowspan=2, , - , β , ⁶⁷Ni , -id=Cobalt-68 , rowspan=2, Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 41 , rowspan=2, 67.9445594(41) , rowspan=2, 200(20) ms , β , Ni , rowspan=2, (7−) , rowspan=2, , - , β, n? , Ni , -id=Cobalt-68m1 , rowspan=2 style="text-indent:1em" , CoOrder of ground state and isomer is uncertain. , rowspan=2 colspan="3" style="text-indent:2em" , 150(150)# keV , rowspan=2, 1.6(3) s , β , Ni , rowspan=2, (2−) , rowspan=2, , - , β, n (>2.6%) , Ni , -id=Cobalt-68m2 , style="text-indent:1em" , Co , colspan="3" style="text-indent:2em" , 195(150)# keV , 101(10) ns , IT , ⁶⁸Co , (1) , , -id=Cobalt-69 , rowspan=2, Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 42 , rowspan=2, 68.945909(92) , rowspan=2, 180(20) ms , β , Ni , rowspan=2, (7/2−) , rowspan=2, , - , β, n? , Ni , -id=Cobalt-69m , style="text-indent:1em" , Co , colspan="3" style="text-indent:2em" , 170(90) keV , 750(250) ms , β , Ni , 1/2−# , , -id=Cobalt-70 , rowspan=3, Co , rowspan=3 style="text-align:right" , 27 , rowspan=3 style="text-align:right" , 43 , rowspan=3, 69.950053(12) , rowspan=3, 508(7) ms , β , Ni , rowspan=3, (1+) , rowspan=3, , - , β, n? , Ni , - , β, 2n? , Ni , -id=Cobalt-70m , rowspan=4 style="text-indent:1em" , Co , rowspan=4 colspan="3" style="text-indent:2em" , 200(200)# keV , rowspan=4, 112(7) ms , β , Ni , rowspan=4, (7−) , rowspan=4, , - , IT? , Co , - , β, n? , Ni , - , β, 2n? , Ni , -id=Cobalt-71 , rowspan=2, Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 44 , rowspan=2, 70.95237(50) , rowspan=2, 80(3) ms , β (97%) , Ni , rowspan=2, (7/2−) , rowspan=2, , - , β, n (3%) , Ni , -id=Cobalt-72 , rowspan=3, Co , rowspan=3 style="text-align:right" , 27 , rowspan=3 style="text-align:right" , 45 , rowspan=3, 71.95674(32)# , rowspan=3, 51.5(3) ms , β (<96%) , Ni , rowspan=3, (6−,7−) , rowspan=3, , - , β, n (>4%) , Ni , - , β, 2n? , Ni , -id=Cobalt-72m , style="text-indent:1em" , Co , colspan="3" style="text-indent:2em" , 200(200)# keV , 47.8(5) ms , β , Ni , (0+,1+) , , -id=Cobalt-73 , rowspan=3, Co , rowspan=3 style="text-align:right" , 27 , rowspan=3 style="text-align:right" , 46 , rowspan=3, 72.95924(32)# , rowspan=3, 42.0(8) ms , β (94%) , Ni , rowspan=3, (7/2−) , rowspan=3, , - , β, n (6%) , Ni , - , β, 2n? , Ni , -id=Cobalt-74 , rowspan=3, Co , rowspan=3 style="text-align:right" , 27 , rowspan=3 style="text-align:right" , 47 , rowspan=3, 73.96399(43)# , rowspan=3, 31.3(13) ms , β (82%) , Ni , rowspan=3, 7−# , rowspan=3, , - , β, n (18%) , Ni , - , β, 2n? , Ni , -id=Cobalt-75 , rowspan=3, Co , rowspan=3 style="text-align:right" , 27 , rowspan=3 style="text-align:right" , 48 , rowspan=3, 74.96719(43)# , rowspan=3, 26.5(12) ms , β (>84%) , Ni , rowspan=3, 7/2−# , rowspan=3, , - , β, n (<16%) , Ni , - , β, 2n? , Ni , -id=Cobalt-76 , rowspan=3, Co , rowspan=3 style="text-align:right" , 27 , rowspan=3 style="text-align:right" , 49 , rowspan=3, 75.97245(54)# , rowspan=3, 23(6) ms , β , Ni , rowspan=3, (8−) , rowspan=3, , - , β, n? , Ni , - , β, 2n? , Ni , -id=Cobalt-76m1 , style="text-indent:1em" , Co , colspan="3" style="text-indent:2em" , 100(100)# keV , 16(4) ms , β , Ni , (1−) , , -id=Cobalt-76m2 , style="text-indent:1em" , Co , colspan="3" style="text-indent:2em" , 740(100)# keV , 2.99(27) μs , IT , Co , (3+) , , -id=Cobalt-77 , rowspan=4, Co , rowspan=4 style="text-align:right" , 27 , rowspan=4 style="text-align:right" , 50 , rowspan=4, 76.97648(64)# , rowspan=4, 15(6) ms , β , Ni , rowspan=4, 7/2−# , rowspan=4, , - , β, n? , Ni , - , β, 2n? , Ni , - , β, 3n? , Ni , -id=Cobalt-78 , Co , style="text-align:right" , 27 , style="text-align:right" , 51 , 77.983 55(75)# , 11# ms
410 ns, β? , Ni , ,

Stellar nucleosynthesis of cobalt-56

One of the terminal nuclear reactions in stars prior to

supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...

produces Ni. Ni then decays to Co, which then decays to Fe. These decays power the luminosity displayed in light decay curves. Both the light decay and

radioactive decay Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

curves are expected to be exponential. Therefore, the light decay curve should give an indication of the nuclear reactions powering it. This has been confirmed by observation of bolometric light decay curves for

SN 1987A SN 1987A was a Type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately from Earth and was the closest observed supernova since Kepler's Supernova in 1604. Light and neutrinos ...

. Between 600 and 800 days after SN1987A occurred, the bolometric light curve decreased at an exponential rate with

values from τ = 68.6 days to τ = 69.6 days. The rate at which the luminosity decreased closely matched the exponential decay of Co with a half-life of τ = 77.233 days.

Use of cobalt radioisotopes in medicine

Cobalt-57 (Co or Co-57) is used in medical tests; it is used as a

radiolabel A radioactive tracer, radiotracer, or radioactive label is a synthetic derivative of a natural compound in which one or more atoms have been replaced by a radionuclide (a radioactive atom). By virtue of its radioactive decay, it can be used to exp ...

for vitamin B uptake. It is useful for the Schilling test.

Cobalt-60 Cobalt-60 (Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2714 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisotop ...

(Co or Co-60) is used in

radiotherapy Radiation therapy or radiotherapy (RT, RTx, or XRT) is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle ...

. It produces two

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 ...

s with energies of 1.17 MeV and 1.33 MeV. The Co source is about 2 cm in

diameter In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions a ...

and as a result produces a

geometric Geometry (; ) is a branch of mathematics concerned with properties of space such as the distance, shape, size, and relative position of figures. Geometry is, along with arithmetic, one of the oldest branches of mathematics. A mathematician w ...

penumbra, making the edge of the

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

field fuzzy. The metal has the unfortunate habit of producing fine dust, causing problems with radiation protection. The Co source is useful for about 5 years but even after this point is still very radioactive, and so cobalt machines have fallen from favor in the Western world where Linacs are common.

Industrial uses for radioactive isotopes

Cobalt-60 (Co) is useful as a gamma ray source because it can be produced in predictable quantities, and for its high

radioactivity Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

simply by exposing natural cobalt to

neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

s in a reactor. The uses for industrial cobalt include: *Sterilization of medical supplies and medical waste *Radiation treatment of foods for sterilization (cold

pasteurization In food processing, pasteurization (American and British English spelling differences#-ise, -ize (-isation, -ization), also pasteurisation) is a process of food preservation in which packaged foods (e.g., milk and fruit juices) are treated wi ...

) *Industrial

radiography Radiography is an imaging technology, imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical ("diagnostic" radiog ...

(e.g., weld integrity radiographs) * Density measurements (e.g., concrete density measurements) *Tank fill height switches Co is used as a source in Mössbauer spectroscopy of iron-containing samples. Electron capture by Co forms an excited state of the Fe nucleus, which in turn decays to the ground state with the emission of a gamma ray. Measurement of the gamma-ray spectrum provides information about the chemical state of the iron atom in the sample.

References

* Isotope masses from: ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes Cobalt

Cobalt Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. ...

List of isotopes

Stellar nucleosynthesis of cobalt-56

Use of cobalt radioisotopes in medicine

Industrial uses for radioactive isotopes

See also

References