Isotopes of zirconium

Naturally occurring zirconium (₄₀Zr) is composed of four stable isotopes (one, ⁹⁴Zr, 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 2.34 × 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 1.61 million years. Thirty other radioisotopes have been observed from ⁷⁷Zr to ¹¹⁴Zr; all have half-lives less than a day except for ⁹⁵Zr (64.032 days), ⁸⁸Zr (83.4 days), and ⁸⁹Zr (78.36 hours). The most stable of the isomeric states is just 4.16 minutes for ^89mZr.

Quick facts Main isotopes, Decay ...

Isotopes of zirconium (₄₀Zr)

Main isotopes^[1]			Decay
Isotope	abundance	half-life (t_1/2)	mode	product
⁸⁸Zr	synth	83.4 d	ε	⁸⁸Y
⁸⁹Zr	synth	78.36 h	β⁺	⁸⁹Y
⁹⁰Zr	51.5%	stable
⁹¹Zr	11.2%	stable
⁹²Zr	17.1%	stable
⁹³Zr	trace	1.61×10⁶ 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 A_r°(Zr)

91.222±0.003^[2]
91.222±0.003 (abridged)^[3]

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Radioactive isotopes above the theoretically stable mass numbers 90-92 decay by electron emission resulting in niobium isotopes, whereas those below by positron emission or electron capture, resulting in yttrium isotopes.

List of isotopes

More information Nuclide, Z ...

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da)^[6] ^{[n 2]}^{[n 3]}	Discovery year^[7]^[8]	Half-life^[1] ^{[n 4]}^{[n 5]}	Decay mode^[1]	Daughter isotope ^{[n 6]}	Spin and parity^[1] ^{[n 7]}^{[n 5]}	Natural abundance (mole fraction)
Nuclide ^{[n 1]}	Excitation energy			Discovery year^[7]^[8]	Half-life^[1] ^{[n 4]}^{[n 5]}	Decay mode^[1]	Daughter isotope ^{[n 6]}	Spin and parity^[1] ^{[n 7]}^{[n 5]}	Normal proportion^[1]	Range of variation
⁷⁷Zr	40	37	76.96608(43)#	2017	100# μs			3/2−#
⁷⁸Zr	40	38	77.95615(43)#	2001	50# ms [>200 ns]			0+
⁷⁹Zr	40	39	78.94979(32)#	1999	56(30) ms	β⁺	⁷⁹Y	5/2+#
⁸⁰Zr	40	40	79.940818(86)^[9]	1987	4.6(6) s	β⁺	⁸⁰Y	0+
⁸¹Zr	40	41	80.938211(11)^[9]	1997	5.5(4) s	β⁺ (99.88%)	⁸¹Y	(3/2−)
⁸¹Zr	40	41	80.938211(11)^[9]	1997	5.5(4) s	β⁺, p (0.12%)	⁸⁰Sr	(3/2−)
⁸²Zr	40	42	81.9317075(17)	1982	32(5) s	β⁺	⁸²Y	0+
⁸³Zr	40	43	82.92923591(70)^[9]	1974	42(2) s	β⁺	⁸³Y	1/2−#
⁸³Zr	40	43	82.92923591(70)^[9]	1974	42(2) s	β⁺, p (?%)	⁸²Sr	1/2−#
^83m1Zr	52.72(5) keV			1988	0.53(12) μs	IT	⁸³Zr	(5/2−)
^83m2Zr	77.04(7) keV			1988	1.8(1) μs	IT	⁸³Zr	(7/2+)
⁸⁴Zr	40	44	83.9233257(59)	1977	25.8(5) min	β⁺	⁸⁴Y	0+
⁸⁵Zr	40	45	84.9214432(69)	1963	7.86(4) min	β⁺	⁸⁵Y	(7/2+)
^85mZr	292.2(3) keV			1976	10.9(3) s	IT (?%)	⁸⁵Zr	1/2−#
^85mZr	292.2(3) keV			1976	10.9(3) s	β⁺ (?%)	⁸⁵Y	1/2−#
⁸⁶Zr	40	46	85.9162968(38)	1951	16.5(1) h	β⁺	⁸⁶Y	0+
⁸⁷Zr	40	47	86.9148173(45)	1949	1.68(1) h	β⁺	⁸⁷Y	9/2+
^87mZr	335.84(19) keV			1972	14.0(2) s	IT	⁸⁷Zr	1/2−
⁸⁸Zr^{[n 8]}	40	48	87.9102207(58)	1951	83.4(3) d	EC	⁸⁸Y	0+
^88mZr	2887.79(6) keV			1971	1.320(25) μs	IT	⁸⁸Zr	8+
⁸⁹Zr	40	49	88.9088798(30)	1938	78.360(23) h	β⁺	⁸⁹Y	9/2+
^89mZr	587.82(10) keV			1940	4.161(10) min	IT (93.77%)	⁸⁹Zr	1/2−
^89mZr	587.82(10) keV			1940	4.161(10) min	β⁺ (6.23%)	⁸⁹Y	1/2−
⁹⁰Zr^{[n 9]}	40	50	89.90469876(13)	1924	Stable			0+	0.5145(4)
^90m1Zr	2319.000(9) keV			1963	809.2(20) ms	IT	⁹⁰Zr	5-
^90m2Zr	3589.418(15) keV			1959	131(4) ns	IT	⁹⁰Zr	8+
⁹¹Zr^{[n 9]}	40	51	90.90564021(10)	1934	Stable			5/2+	0.1122(5)
^91mZr	3167.3(4) keV			1975	4.35(14) μs	IT	⁹¹Zr	(21/2+)
⁹²Zr^{[n 9]}	40	52	91.90503534(10)	1924	Stable			0+	0.1715(3)
⁹³Zr^{[n 10]}	40	53	92.90647066(49)	1950	1.61(5)×10⁶ y	β⁻ (73%)^[10]	^93m1Nb	5/2+
⁹³Zr^{[n 10]}	40	53	92.90647066(49)	1950	1.61(5)×10⁶ y	β⁻ (27%)^[10]	⁹³Nb	5/2+
⁹⁴Zr^{[n 9]}	40	54	93.90631252(18)	1924	Observationally stable^{[n 11]}			0+	0.1738(4)
⁹⁵Zr^{[n 9]}	40	55	94.90804028(93)	1946	64.032(6) d	β⁻	⁹⁵Nb	5/2+
⁹⁶Zr^{[n 9]}^{[n 12]}	40	56	95.90827762(12)	1934	2.34(17)×10¹⁹ y	β⁻β⁻^{[n 13]}	⁹⁶Mo	0+	0.0280(2)
⁹⁷Zr	40	57	96.91096380(13)	1951	16.749(8) h	β⁻	^97mNb	1/2+
^97mZr	1264.35(16) keV			1985	104.8(17) ns	IT	⁹⁷Zr	7/2+
⁹⁸Zr	40	58	97.9127404(91)	1967	30.7(4) s	β⁻	⁹⁸Nb	0+
^98mZr	6601.9(11) keV			2006	1.9(2) μs	IT	⁹⁸Zr	(17−)
⁹⁹Zr	40	59	98.916675(11)	1970	2.1(1) s	β⁻	^99mNb	1/2+
^99mZr	251.96(9) keV			1970	336(5) ns	IT	⁹⁹Zr	7/2+
¹⁰⁰Zr	40	60	99.9180105(87)	1970	7.1(4) s	β⁻	¹⁰⁰Nb	0+
¹⁰¹Zr	40	61	100.9214585(89)	1970	2.29(8) s	β⁻	¹⁰¹Nb	3/2+
¹⁰²Zr	40	62	101.9231542(94)	1970	2.01(8) s	β⁻	¹⁰²Nb	0+
¹⁰³Zr	40	63	102.9272041(99)	1987	1.38(7) s	β⁻ (>99%)	¹⁰³Nb	(5/2−)
¹⁰³Zr	40	63	102.9272041(99)	1987	1.38(7) s	β⁻, n (<1%)	¹⁰²Nb	(5/2−)
¹⁰⁴Zr	40	64	103.929449(10)	1990	920(28) ms	β⁻ (>99%)	¹⁰⁴Nb	0+
¹⁰⁴Zr	40	64	103.929449(10)	1990	920(28) ms	β⁻, n (<1%)	¹⁰³Nb	0+
¹⁰⁵Zr	40	65	104.934022(13)	1992	670(28) ms	β⁻ (>98%)	¹⁰⁵Nb	1/2+#
¹⁰⁵Zr	40	65	104.934022(13)	1992	670(28) ms	β⁻, n (<2%)	¹⁰⁴Nb	1/2+#
¹⁰⁶Zr	40	66	105.93693(22)#	1994	179(6) ms	β⁻ (>98%)	¹⁰⁶Nb	0+
¹⁰⁶Zr	40	66	105.93693(22)#	1994	179(6) ms	β⁻, n (<2%)	¹⁰⁵Nb	0+
¹⁰⁷Zr	40	67	106.94201(32)#	1994	145.7(24) ms	β⁻ (>77%)	¹⁰⁷Nb	5/2+#
¹⁰⁷Zr	40	67	106.94201(32)#	1994	145.7(24) ms	β⁻, n (<23%)	¹⁰⁶Nb	5/2+#
¹⁰⁸Zr	40	68	107.94530(43)#	1997	78.5(20) ms	β⁻	¹⁰⁸Nb	0+
^108mZr	2074.5(8) keV			2011	540(30) ns	IT	¹⁰⁸Zr	(6+)
¹⁰⁹Zr	40	69	108.95091(54)#	1997	56(3) ms	β⁻	¹⁰⁹Nb	5/2+#
¹¹⁰Zr	40	70	109.95468(54)#	1997	37.5(20) ms	β⁻	¹¹⁰Nb	0+
¹¹¹Zr	40	71	110.96084(64)#	2010	24.0(5) ms	β⁻	¹¹¹Nb	5/2+#
¹¹²Zr	40	72	111.96520(75)#	2010	43(21) ms	β⁻	¹¹²Nb	0+
¹¹³Zr	40	73	112.97172(32)#	2018	15# ms [>550 ns]			3/2+
¹¹⁴Zr^[12]	40	74		2021				0+
This table header & footer: view

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[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]
Theorized to also undergo β⁻ decay to ⁹⁶Nb with a partial half-life greater than 2.4×10¹⁹ y^[11]

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 thermal 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.^[13]

Zirconium-89

⁸⁹Zr is a radioisotope of zirconium with a half-life of 78.36 hours, produced by proton irradiation of natural yttrium (⁸⁹Y). Its most prominent gamma photon (99% of decays) has an energy of 909 keV and it emits a positron (as opposed to electron capture) about 23% of decays.^[14] Zirconium-89 is employed in specialized diagnostic applications using positron emission tomography^[15] imaging, for example, with zirconium-89 labeled antibodies (immuno-PET).^[16]

Zirconium-93

More information Thermal, Fast ...

Yield, % per fission^[17]
	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	?

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More information Nuclide, t1⁄2 ...

Long-lived fission products
v
t
e
Nuclide	t_1⁄2	Yield	Q^{[a 1]}	βγ
	(Ma)	(%)^{[a 2]}	(keV)
⁹⁹Tc	0.211	6.1385	294	β
¹²⁶Sn	0.23	0.1084	4050^{[a 3]}	βγ
⁷⁹Se	0.33	0.0447	151	β
¹³⁵Cs	1.33	6.9110^{[a 4]}	269	β
⁹³Zr	1.61	5.4575	91	βγ
¹⁰⁷Pd	6.5	1.2499	33	β
¹²⁹I	16.1	0.8410	194	βγ
[1] Decay energy is split among β, neutrino, and γ if any. [2] Per 65 thermal neutron fissions of ²³⁵U and 35 of ²³⁹Pu. [3] Has decay energy 380 keV, but its decay product ¹²⁶Sb has decay energy 3.67 MeV. [4] Lower in thermal reactors because ¹³⁵Xe, its predecessor, readily absorbs neutrons.

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⁹³Zr is a radioisotope of zirconium with a half-life of 1.61 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 13.9 years (almost entirely by internal conversion, emitting no gamma ray) to the stable ground state of ⁹³Nb, while the remaining 27% of decays directly populate the ground state.^[10] It is one of the 7 long-lived fission products. The low specific activity and low energy of its radiation limit the radioactive hazards of this isotope, and its insolubility makes it unlikely to escape a waste repository; all these are shared with palladium-107.

Nuclear fission produces it at a fission yield of 6.3% (thermal neutron fission of ²³⁵U), one of the most abundant fission products. Nuclear reactors usually contain large amounts of zirconium as fuel rod cladding (see zircalloy), 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.^[18]^[19] 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. The isotope could be recycled: 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 precautions not now taken.

Isotopes of zirconium

List of isotopes

Zirconium-88

Zirconium-89

Zirconium-93

See also

References

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