Isotopes of niobium

Main isotopes of Chemistry:niobium (41Nb) | Iso­tope | Decay

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| abun­dance | half-life (t1/2) | mode | pro­duct
90Nb  | syn | 15 h  | β+ | 90Zr
91Nb  | syn  | 680 y  | ε | 91Zr
91mNb  | syn  | 61 d  | IT | 91Nb
92Nb  | trace | 3.47×107 y  | ε  | 92Zr
γ  | –
92m1Nb  | syn  | 10 d  | ε  | 92Zr
γ | –
93Nb  | 100%  | stable
93mNb  | syn  | 16 y  | IT  | 93Nb
94Nb  | trace  | 20.3×103 y  | β− | 94Mo
γ  | –
95Nb  | syn  | 35 d  | β− | 95Mo
γ  | –
95mNb  | syn  | 4 d  | IT  | 95Nb
96Nb  | syn  | 24 h  | β− | 96Mo
Standard atomic weight Ar, standard(Nb)|

* 92.90637(2)[1]

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Naturally occurring niobium (41Nb) is composed of one stable isotope (93Nb). The most stable radioisotope is 92Nb with a half-life of 34.7 million years, followed by are 94Nb at a half-life of 20,400 years and 91Nb at 680 years. Other radioisotopes that have been synthesized range from 82Nb to 110Nb; these have half-lives that are less than two hours, except 95Nb (34.991 days), 96Nb (23.35 hours) and 90Nb (14.60 hours).

The most stable of the meta states is 93mNb with excitation energy 31 keV and a 16.1 year half-life; this is produced in the decay of 93Zr. The primary decay mode before stable 93Nb is electron capture to zirconium isotopes and the primary mode after is beta emission, with delayed neutron emission starting at 104Nb, leading to molybdenum isotopes.

Only 95Nb, along with 97Nb (72 minutes) and heavier isotopes (seconds) are fission products in significant quantity, as the other isotopes are shadowed by stable or very long-lived (93) isotopes of the preceding element zirconium from the usual mode of production through beta decay of neutron-rich fission fragments. 95Nb is the decay product of 95Zr (64 days), so disappearance of 95Nb in used nuclear fuel is slower than would be expected from its own 35-day half-life alone.

## Contents

* 1 List of isotopes
* 2 Niobium-92
* 3 See also
* 4 References

## List of isotopes

Nuclide
[n 1] | Z | N | Isotopic mass (u)
[n 2][n 3] | Half-life
[n 4] | Decay
mode
[n 5] | Daughter
isotope
[n 6][n 7] | Spin and
parity
[n 8][n 4] | Physics:Natural abundance (mole fraction)

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Excitation energy[n 4] | Normal proportion  | Range of variation
81Nb  | 41  | 40  |  |  |  |  |  |
82Nb  | 41  | 41  | 81.94438(32)  | 51(5) ms  | β+ | 82Zr  | (0+)  |
82mNb  | 1180(1) keV  | 93(20) ns  | IT  | 82Nb  | (5+)  |
83Nb  | 41  | 42  | 82.938133(10)[2] | 3.9(2) s  | β+ | 83Zr  | 9/2+#  |
84Nb  | 41  | 43  | 83.93430571(43)  | 9.8(9) s  | β+ | 84Zr  | (1+)  |
84m1Nb  | 48(1) keV  | 176(46) ns  | IT  | 84Nb  | (3+)  |
84m2Nb  | 337.7(4) keV  | 92(5) ns  | IT  | 84Nb  | (5−)  |
85Nb  | 41  | 44  | 84.9288458(44)  | 20.5(7) s  | β+ | 85Zr  | 9/2+#  |
85mNb  | 150(80)# keV  | 3.3(9) s  | IT (?%)  | 85Nb  | (1/2−)  |
β+ (?%)  | 85Zr
86Nb  | 41  | 45  | 85.9257815(59)  | 88(1) s  | β+ | 86Zr  | (6+)  |
86mNb[n 9] | 150(100)# keV  | 20# s  | β+ | 86Zr  | (0−,1−,2−)  |
87Nb  | 41  | 46  | 86.9206925(73)  | 3.7(1) min  | β+ | 87Zr  | (1/2)−  |
87mNb  | 3.9(1) keV  | 2.6(1) min  | β+ | 87Zr  | (9/2)+  |
88Nb  | 41  | 47  | 87.918226(62)  | 14.50(11) min  | β+ | 88Zr  | (8+)  |
88mNb[n 9] | 130(120) keV  | 7.7(1) min  | β+ | 88Zr  | (4−)  |
89Nb  | 41  | 48  | 88.913445(25)  | 2.03(7) h  | β+ | 89Zr  | (9/2+)  |
89mNb[n 9] | 0(30)# keV  | 1.10(3) h  | β+ | 89Zr  | (1/2)−  |
90Nb  | 41  | 49  | 89.9112592(36)  | 14.60(5) h  | β+ | 90Zr | 8+  |
90m1Nb  | 122.370(22) keV  | 63(2) μs  | IT  | 90Nb  | 6+  |
90m2Nb  | 124.67(25) keV  | 18.81(6) s  | IT  | 90Nb  | 4-  |
90m3Nb  | 171.10(10) keV  | <1 μs  | IT  | 90Nb  | 7+  |
90m4Nb  | 382.01(25) keV  | 6.19(8) ms  | IT  | 90m1Nb  | 1+  |
90m5Nb  | 1880.21(20) keV  | 471(6) ns  | IT  | 90Nb  | (11−)  |
91Nb  | 41  | 50  | 90.9069903(31)  | 680(130) y  | EC (99.99%)  | 91Zr | 9/2+  |
β+ (0.0138%)
91m1Nb  | 104.60(5) keV  | 60.86(22) d  | IT (96.6%)  | 91Nb  | 1/2−  |
EC (3.4%)  | 91Zr
β+ (0.0028%)
91m2Nb  | 2034.42(20) keV  | 3.76(12) μs  | IT  | 91Nb  | (17/2−)  |
92Nb  | 41  | 51  | 91.9071886(19)  | 3.47(24)×107 y  | β+ | 92Zr | 7+  | Trace
92m1Nb  | 135.5(4) keV  | 10.116(13) d  | β+ | 92Zr | (2)+  |
92m2Nb  | 225.8(4) keV  | 5.9(2) μs  | IT  | 92Nb  | (2)−  |
92m3Nb  | 2203.3(4) keV  | 167(4) ns  | IT  | 92Nb  | (11−)  |
93Nb  | 41  | 52  | 92.9063732(16)  | Stable | 9/2+  | 1.0000
93m1Nb  | 30.760(5) keV  | 16.12(12) y  | IT  | 93Nb | 1/2−  |
93m2Nb  | 7460(17) keV  | 1.5(5) μs  | IT  | 93Nb | 33/2−#  |
94Nb  | 41  | 53  | 93.9072790(16)  | 2.04(4)×104 y  | β− | 94Mo | 6+  | Trace
94mNb  | 40.892(12) keV  | 6.263(4) min  | IT (99.50%)  | 94Nb  | 3+  |
β− (0.50%)  | 94Mo
95Nb[n 10] | 41  | 54  | 94.90683111(55)  | 34.991(6) d  | β− | 95Mo | 9/2+  |
95mNb[n 10] | 235.69(2) keV  | 3.61(3) d  | IT (94.4%)  | 95Nb  | 1/2−  |
β− (5.6%)  | 95Mo
96Nb  | 41  | 55  | 95.90810159(16)  | 23.35(5) h  | β− | 96Mo | 6+  |
97Nb  | 41  | 56  | 96.9081016(46)  | 72.1(7) min  | β− | 97Mo | 9/2+  |
97mNb  | 743.35(3) keV  | 58.7(18) s  | IT  | 97Nb  | 1/2−  |
98Nb  | 41  | 57  | 97.9103326(54)  | 2.86(6) s  | β− | 98Mo | 1+  |
98mNb  | 84(4) keV  | 51.1(4) min  | β− | 98Mo | (5)+  |
99Nb  | 41  | 58  | 98.911609(13)  | 15.0(2) s  | β− | 99Mo  | 9/2+  |
99mNb  | 365.27(8) keV  | 2.5(2) min  | β− (?%)  | 99Mo  | 1/2−  |
IT (?%)  | 99Nb
100Nb  | 41  | 59  | 99.9143406(86)  | 1.5(2) s  | β− | 100Mo | 1+  |
100m1Nb  | 313(8) keV  | 2.99(11) s  | β− | 100Mo | (5+)  |
100m2Nb  | 347(8) keV  | 460(60) ns  | IT  | 100Nb  | (4−,5−)  |
100m3Nb  | 734(8) keV  | 12.43(26) μs  | IT  | 100Nb  | (8−)  |
101Nb  | 41  | 60  | 100.9153065(40)  | 7.1(3) s  | β− | 101Mo  | 5/2+  |
102Nb  | 41  | 61  | 101.9180904(27)  | 4.3(4) s  | β− | 102Mo  | (4+)  |
102mNb  | 94(7) keV  | 1.31(16) s  | β− | 102Mo  | (1+)  |
103Nb  | 41  | 62  | 102.9194534(42)  | 1.34(7) s  | β− | 103Mo  | 5/2+  |
104Nb  | 41  | 63  | 103.9229077(19)  | 0.98(5) s  | β− (99.95%)  | 104Mo  | (1+)  |
β−, n (0.05%)  | 103Mo
104mNb[n 9] | 9.8(26) keV  | 4.9(3) s  | β− (99.94%)  | 104Mo  | (0−,1−)  |
β−, n (0.06%)  | 103Mo
105Nb  | 41  | 64  | 104.9249426(43)  | 2.91(5) s  | β− (98.3%)  | 105Mo  | (5/2+)  |
β−, n (1.7%)  | 104Mo
106Nb  | 41  | 65  | 105.9289285(15)  | 900(20) ms  | β− (95.5%)  | 106Mo  | 1−#  |
β−, n (4.5%)  | 105Mo
106m1Nb  | 100(50)# keV  | 1.20(6) s  | β− | 106Mo  | (4−)  |
106m2Nb  | 204.8(5) keV  | 820(38) ns  | IT  | 106Nb  | (3+)  |
107Nb  | 41  | 66  | 106.9315897(86)  | 286(8) ms  | β− (92.6%)  | 107Mo  | (5/2+)  |
β−, n (7.4%)  | 106Mo
108Nb  | 41  | 67  | 107.9360756(88)  | 201(4) ms  | β− (93.7%)  | 108Mo  | (2+)  |
β−, n (6.3%)  | 107Mo
108mNb  | 166.6(5) keV  | 109(2) ns  | IT  | 108Nb  | 6−#  |
109Nb  | 41  | 68  | 108.93914(46)  | 106.9(49) ms  | β− (69%)  | 109Mo  | 3/2−#  |
β−, n (31%)  | 108Mo
109mNb  | 312.5(4) keV  | 115(8) ns  | IT  | 109Nb  | 7/2+#  |
110Nb  | 41  | 69  | 109.94384(90)  | 75(1) ms  | β− (60%)  | 110Mo  | 5+#  |
β−, n (40%)  | 109Mo
110mNb[n 9] | 100(50)# keV  | 94(9) ms  | β− (60%)  | 110Mo  | 2+#  |
β−, n (40%)  | 109Mo
111Nb  | 41  | 70  | 110.94744(32)#  | 54(2) ms  | β− | 111Mo  | 3/2−#  |
112Nb  | 41  | 71  | 111.95269(32)#  | 38(2) ms  | β− | 112Mo  | 1+#  |
113Nb  | 41  | 72  | 112.95683(43)#  | 32(4) ms  | β− | 113Mo  | 3/2−#  |
114Nb  | 41  | 73  | 113.96247(54)#  | 17(5) ms  | β− | 114Mo  | 2−#  |
115Nb  | 41  | 74  | 114.96685(54)#  | 23(8) ms  | β− | 115Mo  | 3/2−#  |
116Nb  | 41  | 75  | 115.97291(32)#  | 12# ms
[>550 ns]  |  |  | 1−#  |
117Nb[3] | 41  | 76  |  |  |  |  |  |

1. ↑ mNb - 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. ↑ 4.0 4.1 4.2 # - Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. ↑ Modes of decay:  EC: | Electron capture

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IT: | Isomeric transition
n: | Neutron emission
p: | Proton emission
6. ↑ Bold italics symbol as daughter - Daughter product is nearly stable.
7. ↑ Bold symbol as daughter - Daughter product is stable.
8. ↑ ( ) spin value - Indicates spin with weak assignment arguments.
9. ↑ 9.0 9.1 9.2 9.3 9.4 Order of ground state and isomer is uncertain.
10. ↑ 10.0 10.1 Fission product

## Niobium-92

Niobium-92 is an extinct radionuclide[4] with a half-life of 34.7 million years, decaying predominantly via β+ decay. Its abundance relative to the stable 93Nb in the early Solar System, estimated at 1.7×10−5, has been measured to investigate the origin of p-nuclei.[4][5] A higher initial abundance of 92Nb has been estimated for material in the outer protosolar disk (sampled from the meteorite NWA 6704), suggesting that this nuclide was predominantly formed via the gamma process (photodisintegration) in a nearby core-collapse supernova.[6]

Niobium-92, along with niobium-94, has been detected in refined samples of terrestrial niobium and may originate from bombardment by cosmic ray muons in Earth's crust.[7]

## See also

Daughter products other than niobium

* Isotopes of molybdenum
* Isotopes of zirconium

## References

1. ↑ Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265–91. doi:10.1515/pac-2015-0305.
2. ↑ Kimura, S.; Wada, M.; Fu, C. Y.; Fukuda, N.; Hirayama, Y.; Hou, D. S.; Iimura, S.; Ishiyama, H. et al. (8 October 2025). "Precision Mass Measurements around Mo 84 Rule Out ZrNb Cycle Formation in the Rapid Proton-Capture Process at Type I X-Ray Bursts". Physical Review Letters 135 (15). doi:10.1103/2dyn-q7wp. PMID 41138077.
3. ↑ Sumikama, T. et al. (2021). "Observation of new neutron-rich isotopes in the vicinity of Zr110". Physical Review C 103 (1). doi:10.1103/PhysRevC.103.014614. Bibcode: 2021PhRvC.103a4614S. https://journals.aps.org/prc/abstract/10.1103/PhysRevC.103.014614.
4. ↑ 4.0 4.1 Iizuka, Tsuyoshi; Lai, Yi-Jen; Akram, Waheed; Amelin, Yuri; Schönbächler, Maria (2016). "The initial abundance and distribution of 92Nb in the Solar System". Earth and Planetary Science Letters 439: 172–181. doi:10.1016/j.epsl.2016.02.005. Bibcode: 2016E&PSL.439..172I.
5. ↑ Hibiya, Y; Iizuka, T; Enomoto, H (2019). "THE INITIAL ABUNDANCE OF NIOBIUM-92 IN THE OUTER SOLAR SYSTEM". Lunar and Planetary Science Conference (50th ed.). https://www.hou.usra.edu/meetings/lpsc2019/pdf/1781.pdf. Retrieved 7 September 2019.
6. ↑ Hibiya, Y.; Iizuka, T.; Enomoto, H.; Hayakawa, T. (2023). "Evidence for enrichment of niobium-92 in the outer protosolar disk". Astrophysical Journal Letters 942 (L15): L15. doi:10.3847/2041-8213/acab5d. Bibcode: 2023ApJ...942L..15H.
7. ↑ Clayton, Donald D.; Morgan, John A. (1977). "Muon production of 92,94Nb in the Earth's crust". Nature 266 (5604): 712–713. doi:10.1038/266712a0.

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