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Zirconium-93

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Zirconium-93

Naturally occurring zirconium (Zr) 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;[1] it can also undergo single beta decay which is not yet observed, but the theoretically predicted value of T½ is 2.4×1020 years.[2] The second most stable radioisotope is 93Zr which has a half-life of 1.53 million years. Twenty-seven other radioisotopes have been observed. All have half-lives less than a day except for 95Zr (64.02 days), 88Zr (63.4 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.

Zirconium is the heaviest element that can be formed from symmetric fusion, from either 45Sc, or 46Ca producing 90Zr (after two beta-plus decays from 90Mo) and 92Zr respectively. All heavier elements are formed either through asymmetric fusion or during the collapse of supernovae. As most of these are energy-absorbing processes, most nuclides of elements heavier than zirconium are theoretically unstable to spontaneous fission, although in many cases, the half-life for this is too long to have been observed. See list of nuclides for a tabulation.


Standard atomic mass: 91.224(2) u.

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 imaging, for example, with zirconium-89 labeled antibodies (immuno-PET).Zirconium 89 decay Table

Zirconium-93

Yield, % per fission[4]
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  ?


93Zr is a radioisotope of zirconium with a half-life of 1.53 million years, decaying with a low-energy beta particle to Niobium-93m, which decays with a halflife of 14 years and a low-energy gamma ray to ordinary 93Nb. 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.

93Zr also has a low neutron capture cross section of 2.70 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 than are Tc-99 and I-129. Mobility in soil is relatively low, so that geological disposal may be an adequate solution.

  • ANL fact sheet

Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life[n 1] decay
mode(s)[5][n 2]
daughter
isotope(s)[n 3]
nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
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+ 86Y (9/2)+
87mZr 335.84(19) keV 14.0(2) s IT 87Zr (1/2)-
88Zr 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 4] 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 4] 40 51 90.9056458(25) Stable 5/2+ 0.1122(5)
91mZr 3167.3(4) keV 4.35(14) µs (21/2+)
92Zr[n 4] 40 52 91.9050408(25) Stable[n 5] 0+ 0.1715(8)
93Zr[n 6] 40 53 92.9064760(25) 1.53(10)×106 a β- 93Nb 5/2+
94Zr[n 4] 40 54 93.9063152(26) Observationally Stable[n 7] 0+ 0.1738(28)
95Zr[n 4] 40 55 94.9080426(26) 64.032(6) d β- 95Nb 5/2+
96Zr[n 8][n 4] 40 56 95.9082734(30) 20(4)×1018 a β-β-[n 9] 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+

Notes

  • Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

  • Isotope masses from:
  • Isotopic compositions and standard atomic masses from:
  • Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.


Isotopes of yttrium Isotopes of zirconium Isotopes of niobium
Table of nuclides
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