Isotopes of zirconium

Naturally occurring zirconium (₄₀Zr) is composed of four stable isotopes (of which one 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 2.0×10¹⁹ years;^[4] 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.^[5] 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 for isotopes lighter than ⁹²Zr, and the primary mode for heavier isotopes is beta decay.

Isotopes of zirconium (₄₀Zr)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 88Zr synth 83.4 d ε 88Y γ – 89Zr synth 78.4 h ε 89Y β+ 89Y γ – 90Zr 51.5% stable 91Zr 11.2% stable 92Zr 17.1% stable 93Zr trace 1.53×106 y β− 93Nb 94Zr 17.4% stable 95Zr synth 64.032 d β− 95Nb 96Zr 2.80% 2.34×1019 y β−β− 96Mo
Standard atomic weight Ar°(Zr)
	91.222±0.003[2] 91.222±0.003 (abridged)[3]
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List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life [n 4][n 5]	Decay mode	Daughter isotope [n 6]	Spin and parity [n 7][n 5]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
77Zr	40	37	76.96608(43)#	100# μs			3/2−#
78Zr	40	38	77.95523(54)#	50# ms [>170 ns]			0+
79Zr	40	39	78.94916(43)#	56(30) ms	β+, p	78Sr	5/2+#
					β+	79Y
80Zr	40	40	79.9404(16)	4.6(6) s	β+	80Y	0+
81Zr	40	41	80.93721(18)	5.5(4) s	β+ (>99.9%)	81Y	(3/2−)#
					β+, p (<.1%)	80Sr
82Zr	40	42	81.93109(24)#	32(5) s	β+	82Y	0+
83Zr	40	43	82.92865(10)	41.6(24) s	β+ (>99.9%)	83Y	(1/2−)#
					β+, p (<.1%)	82Sr
84Zr	40	44	83.92325(21)#	25.9(7) min	β+	84Y	0+
85Zr	40	45	84.92147(11)	7.86(4) min	β+	85Y	7/2+
85mZr	292.2(3) keV			10.9(3) s	IT (92%)	85Zr	(1/2−)
					β+ (8%)	85Y
86Zr	40	46	85.91647(3)	16.5(1) h	β+	86Y	0+
87Zr	40	47	86.914816(9)	1.68(1) h	β+	87Y	(9/2)+
87mZr	335.84(19) keV			14.0(2) s	IT	87Zr	(1/2)−
88Zr[n 8]	40	48	87.910227(11)	83.4(3) d	EC	88Y	0+
89Zr	40	49	88.908890(4)	78.41(12) h	β+	89Y	9/2+
89mZr	587.82(10) keV			4.161(17) min	IT (93.77%)	89Zr	1/2−
					β+ (6.23%)	89Y
90Zr[n 9]	40	50	89.9047044(25)	Stable			0+	0.5145(40)
90m1Zr	2319.000(10) keV			809.2(20) ms	IT	90Zr	5-
90m2Zr	3589.419(16) keV			131(4) ns			8+
91Zr[n 9]	40	51	90.9056458(25)	Stable			5/2+	0.1122(5)
91mZr	3167.3(4) keV			4.35(14) μs			(21/2+)
92Zr[n 9]	40	52	91.9050408(25)	Stable			0+	0.1715(8)
93Zr[n 10]	40	53	92.9064760(25)	1.53(10)×106 y	β− (73%)	93mNb	5/2+
					β− (27%)	93Nb
94Zr[n 9]	40	54	93.9063152(26)	Observationally stable[n 11]			0+	0.1738(28)
95Zr[n 9]	40	55	94.9080426(26)	64.032(6) d	β−	95Nb	5/2+
96Zr[n 12][n 9][n 13]	40	56	95.9082734(30)	2.0(4)×1019 y	β−β−[n 14]	96Mo	0+	0.0280(9)
97Zr	40	57	96.9109531(30)	16.744(11) h	β−	97mNb	1/2+
98Zr	40	58	97.912735(21)	30.7(4) s	β−	98Nb	0+
99Zr	40	59	98.916512(22)	2.1(1) s	β−	99mNb	1/2+
100Zr	40	60	99.91776(4)	7.1(4) s	β−	100Nb	0+
101Zr	40	61	100.92114(3)	2.3(1) s	β−	101Nb	3/2+
102Zr	40	62	101.92298(5)	2.9(2) s	β−	102Nb	0+
103Zr	40	63	102.92660(12)	1.3(1) s	β−	103Nb	(5/2−)
104Zr	40	64	103.92878(43)#	1.2(3) s	β−	104Nb	0+
105Zr	40	65	104.93305(43)#	0.6(1) s	β− (>99.9%)	105Nb
					β−, n (<.1%)	104Nb
106Zr	40	66	105.93591(54)#	200# ms [>300 ns]	β−	106Nb	0+
107Zr	40	67	106.94075(32)#	150# ms [>300 ns]	β−	107Nb
108Zr	40	68	107.94396(64)#	80# ms [>300 ns]	β−	108Nb	0+
109Zr	40	69	108.94924(54)#	60# ms [>300 ns]
110Zr	40	70	109.95287(86)#	30# ms [>300 ns]			0+
111Zr[7]	40	71
112Zr[7]	40	72					0+
113Zr[8]	40	73
114Zr[9]	40	74					0+
This table header & footer: view

1. ^mZr – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. Bold half-life – nearly stable, half-life longer than age of universe.
5. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
6. Bold symbol as daughter – Daughter product is stable.
7. ( ) spin value – Indicates spin with weak assignment arguments.
8. Second most powerful known neutron absorber
9. Fission product
10. Long-lived fission product
11. Believed to decay by β⁻β⁻ to ⁹⁴Mo with a half-life over 1.1×10¹⁷ years
12. Primordial radionuclide
13. Predicted to be capable of undergoing triple beta decay and quadruple beta decay with very long partial half-lives
14. Theorized to also undergo β⁻ decay to ⁹⁶Nb with a partial half-life greater than 2.4×10¹⁹ y^[6]

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 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.^[10]

Zirconium-89

⁸⁹Zr 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^[11] imaging, for example, with zirconium-89 labeled antibodies (immuno-PET).^[12] For a decay table, see Maria Vosjan. "Zirconium-89 (⁸⁹Zr)". Cyclotron.nl.

Zirconium-93

Yield, % per fission^[13]

	Thermal	Fast	14 MeV
232Th	not fissile	6.70 ± 0.40	5.58 ± 0.16
233U	6.979 ± 0.098	6.94 ± 0.07	5.38 ± 0.32
235U	6.346 ± 0.044	6.25 ± 0.04	5.19 ± 0.31
238U	not fissile	4.913 ± 0.098	4.53 ± 0.13
239Pu	3.80 ± 0.03	3.82 ± 0.03	3.0 ± 0.3
241Pu	2.98 ± 0.04	2.98 ± 0.33	?

Long-lived fission products

• v
• t
• e

Nuclide	t1⁄2	Yield	Q[a 1]	βγ
	(Ma)	(%)[a 2]	(keV)
99Tc	0.211	6.1385	294	β
126Sn	0.230	0.1084	4050[a 3]	βγ
79Se	0.327	0.0447	151	β
135Cs	1.33	6.9110[a 4]	269	β
93Zr	1.53	5.4575	91	βγ
107Pd	6.5	1.2499	33	β
129I	16.14	0.8410	194	βγ
Decay energy is split among β, neutrino, and γ if any. Per 65 thermal neutron fissions of 235U and 35 of 239Pu. Has decay energy 380 keV, but its decay product 126Sb has decay energy 3.67 MeV. Lower in thermal reactors because 135Xe, its predecessor, readily absorbs neutrons.

⁹³Zr 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 ⁹³Nb, while the remaining 27% of decays directly populate the ground state.^[14] 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 ²³⁵U), 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 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.^[15][16] 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. 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.

References

1. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
2. "Standard Atomic Weights: Zirconium". CIAAW. 2024.
3. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
4. "List of Adopted Double Beta (ββ) Decay Values". National Nuclear Data Center, Brookhaven National Laboratory.
5. H Heiskanen; M T Mustonen; J Suhonen (30 March 2007). "Theoretical half-life for beta decay of ⁹⁶Zr". Journal of Physics G: Nuclear and Particle Physics. 34 (5): 837–843. doi:10.1088/0954-3899/34/5/005.
6. Finch, S.W.; Tornow, W. (2016). "Search for the β decay of ⁹⁶Zr". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 806: 70–74. Bibcode:2016NIMPA.806...70F. doi:10.1016/j.nima.2015.09.098.
7. Ohnishi, Tetsuya; Kubo, Toshiyuki; Kusaka, Kensuke; et al. (2010). "Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a ²³⁸U Beam at 345 MeV/nucleon". J. Phys. Soc. Jpn. 79 (7). Physical Society of Japan: 073201. arXiv:1006.0305. Bibcode:2010JPSJ...79g3201T. doi:10.1143/JPSJ.79.073201.
8. Shimizu, Yohei; et al. (2018). "Observation of New Neutron-rich Isotopes among Fission Fragments from In-flight Fission of 345MeV=nucleon 238U: Search for New Isotopes Conducted Concurrently with Decay Measurement Campaigns". Journal of the Physical Society of Japan. 87 (1): 014203. Bibcode:2018JPSJ...87a4203S. doi:10.7566/JPSJ.87.014203.
9. Sumikama, T.; et al. (2021). "Observation of new neutron-rich isotopes in the vicinity of Zr110". Physical Review C. 103 (1): 014614. Bibcode:2021PhRvC.103a4614S. doi:10.1103/PhysRevC.103.014614. hdl:10261/260248. S2CID 234019083.
10. Shusterman, J.A.; Scielzo, N.D.; Thomas, K.J.; Norman, E.B.; Lapi, S.E.; Loveless, C.S.; Peters, N.J.; Robertson, J.D.; Shaughnessy, D.A.; Tonchev, A.P. (2019). "The surprisingly large neutron capture cross-section of ⁸⁸Zr". Nature. 565 (7739): 328–330. Bibcode:2019Natur.565..328S. doi:10.1038/s41586-018-0838-z. OSTI 1512575. PMID 30617314. S2CID 57574387.
11. Dilworth, Jonathan R.; Pascu, Sofia I. (2018). "The chemistry of PET imaging with zirconium-89". Chemical Society Reviews. 47 (8): 2554–2571. doi:10.1039/C7CS00014F. PMID 29557435.
12. Van Dongen, GA; Vosjan, MJ (August 2010). "Immuno-positron emission tomography: shedding light on clinical antibody therapy". Cancer Biotherapy and Radiopharmaceuticals. 25 (4): 375–85. doi:10.1089/cbr.2010.0812. PMID 20707716.
13. M. B. Chadwick et al, "ENDF/B-VII.1: Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data", Nucl. Data Sheets 112(2011)2887. (accessed at www-nds.iaea.org/exfor/endf.htm)
14. Cassette, P.; Chartier, F.; Isnard, H.; Fréchou, C.; Laszak, I.; Degros, J.P.; Bé, M.M.; Lépy, M.C.; Tartes, I. (2010). "Determination of ⁹³Zr decay scheme and half-life". Applied Radiation and Isotopes. 68 (1): 122–130. doi:10.1016/j.apradiso.2009.08.011. PMID 19734052.
15. "ENDF/B-VII.1 Zr-93(n,g)". National Nuclear Data Center, Brookhaven National Laboratory. 2011-12-22. Archived from the original on 2009-07-20. Retrieved 2014-11-20.
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• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
• "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.