Isotopes of niobium

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. The next longest-lived niobium isotopes are ⁹⁴Nb (half-life: 20,300 years) and ⁹¹Nb with a half-life of 680 years. There is also a meta state of ⁹³Nb at 31 keV whose half-life is 16.13 years. Twenty-three other radioisotopes have been characterized. Most of these have half-lives that are less than two hours, except ⁹⁵Nb (35 days), ⁹⁶Nb (23.4 hours) and ⁹⁰Nb (14.6 hours). The primary decay mode before stable ⁹³Nb is electron capture and the primary mode after is beta emission with some neutron emission occurring in ^104–110Nb.

Main isotopes of niobium (₄₁Nb)

Iso­tope Decay 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 3.47×10^7 y ε ^92Zr γ – ^92m1Nb syn 10 d ε ^92Zr γ – ^93Nb 100% stable ^93mNb syn 16 y IT ^93Nb ^94Nb trace 20.3×10^3 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]

Only ⁹⁵Nb (35 days) and ⁹⁷Nb (72 minutes) and heavier isotopes (half-lives in seconds) are fission products in significant quantity, as the other isotopes are shadowed by stable or very long-lived (⁹³Zr) isotopes of the preceding element zirconium from production via 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. Small amounts of other isotopes may be produced as direct fission products.

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [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]	Natural abundance (mole fraction)
	Excitation energy[n 4]							Normal proportion	Range of variation
^81Nb	41	40	80.94903(161)#	<44 ns	β^+, p	^80Y	3/2−#
					p	^80Zr
					β^+	^81Zr
^82Nb	41	41	81.94313(32)#	51(5) ms	β^+	^82Zr	0+
^83Nb	41	42	82.93671(34)	4.1(3) s	β^+	^83Zr	(5/2+)
^84Nb	41	43	83.93357(32)#	9.8(9) s	β^+ (>99.9%)	^84Zr	3+
					β^+, p (<.1%)	^83Y
^84mNb	338(10) keV			103(19) ns			(5−)
^85Nb	41	44	84.92791(24)	20.9(7) s	β^+	^85Zr	(9/2+)
^85mNb	759.0(10) keV			12(5) s			(1/2−)
^86Nb	41	45	85.92504(9)	88(1) s	β^+	^86Zr	(6+)
^86mNb	250(160)# keV			56(8) s	β^+	^86Zr	high
^87Nb	41	46	86.92036(7)	3.75(9) min	β^+	^87Zr	(1/2−)
^87mNb	3.84(14) keV			2.6(1) min	β^+	^87Zr	(9/2+)#
^88Nb	41	47	87.91833(11)	14.55(6) min	β^+	^88Zr	(8+)
^88mNb	40(140) keV			7.8(1) min	β^+	^88Zr	(4−)
^89Nb	41	48	88.913418(29)	2.03(7) h	β^+	^89Zr	(9/2+)
^89mNb	0(30)# keV			1.10(3) h	β^+	^89Zr	(1/2)−
^90Nb	41	49	89.911265(5)	14.60(5) h	β^+	^90Zr	8+
^90m1Nb	122.370(22) keV			63(2) µs			6+
^90m2Nb	124.67(25) keV			18.81(6) s	IT	^90Nb	4-
^90m3Nb	171.10(10) keV			<1 µs			7+
^90m4Nb	382.01(25) keV			6.19(8) ms			1+
^90m5Nb	1880.21(20) keV			472(13) ns			(11−)
^91Nb	41	50	90.906996(4)	680(130) a	EC (99.98%)	^91Zr	9/2+
					β^+ (.013%)	^91Zr
^91m1Nb	104.60(5) keV			60.86(22) d	IT (93%)	^91Nb	1/2−
					EC (7%)	^91Zr
					β^+ (.0028%)	^91Zr
^91m2Nb	2034.35(19) keV			3.76(12) µs			(17/2−)
^92Nb	41	51	91.907194(3)	3.47(24)×10^7 a	β^+ (99.95%)	^92Zr	(7)+
					β^− (.05%)	^92Mo
^92m1Nb	135.5(4) keV			10.15(2) d	β^+	^92Zr	(2)+
^92m2Nb	225.7(4) keV			5.9(2) µs			(2)−
^92m3Nb	2203.3(4) keV			167(4) ns			(11−)
^93Nb	41	52	92.9063781(26)	Stable			9/2+	1.0000
^93mNb	30.77(2) keV			16.13(14) a	IT	^93Nb	1/2−
^94Nb	41	53	93.9072839(26)	2.03(16)×10^4 a	β^−	^94Mo	(6)+
^94mNb	40.902(12) keV			6.263(4) min	IT (99.5%)	^94Nb	3+
					β^− (.5%)	^94Mo
^95Nb	41	54	94.9068358(21)	34.991(6) d	β^−	^95Mo	9/2+
^95mNb	235.690(20) keV			3.61(3) d	IT (94.4%)	^95Nb	1/2−
					β^− (5.6%)	^95Mo
^96Nb	41	55	95.908101(4)	23.35(5) h	β^−	^96Mo	6+
^97Nb	41	56	96.9080986(27)	72.1(7) min	β^−	^97Mo	9/2+
^97mNb	743.35(3) keV			52.7(18) s	IT	^97Nb	1/2−
^98Nb	41	57	97.910328(6)	2.86(6) s	β^−	^98Mo	1+
^98mNb	84(4) keV			51.3(4) min	β^− (99.9%)	^98Mo	(5+)
					IT (.1%)	^98Nb
^99Nb	41	58	98.911618(14)	15.0(2) s	β^−	^99Mo	9/2+
^99mNb	365.29(14) keV			2.6(2) min	β^− (96.2%)	^99Mo	1/2−
					IT (3.8%)	^99Nb
^100Nb	41	59	99.914182(28)	1.5(2) s	β^−	^100Mo	1+
^100mNb	470(40) keV			2.99(11) s	β^−	^100Mo	(4+, 5+)
^101Nb	41	60	100.915252(20)	7.1(3) s	β^−	^101Mo	(5/2#)+
^102Nb	41	61	101.91804(4)	1.3(2) s	β^−	^102Mo	1+
^102mNb	130(50) keV			4.3(4) s	β^−	^102Mo	high
^103Nb	41	62	102.91914(7)	1.5(2) s	β^−	^103Mo	(5/2+)
^104Nb	41	63	103.92246(11)	4.9(3) s	β^− (99.94%)	^104Mo	(1+)
					β^−, n (.06%)	^103Mo
^104mNb	220(120) keV			940(40) ms	β^− (99.95%)	^104Mo	high
					β^−, n (.05%)	^103Mo
^105Nb	41	64	104.92394(11)	2.95(6) s	β^− (98.3%)	^105Mo	(5/2+)#
					β^−, n (1.7%)	^104Mo
^106Nb	41	65	105.92797(21)#	920(40) ms	β^− (95.5%)	^106Mo	2+#
					β^−, n (4.5%)	^105Mo
^107Nb	41	66	106.93031(43)#	300(9) ms	β^− (94%)	^107Mo	5/2+#
					β^−, n (6%)	^106Mo
^108Nb	41	67	107.93484(32)#	0.193(17) s	β^− (93.8%)	^108Mo	(2+)
					β^−, n (6.2%)	^107Mo
^109Nb	41	68	108.93763(54)#	190(30) ms	β^− (69%)	^109Mo	5/2+#
					β^−, n (69%)	^108Mo
^110Nb	41	69	109.94244(54)#	170(20) ms	β^− (60%)	^110Mo	2+#
					β^−, n (40%)	^109Mo
^111Nb	41	70	110.94565(54)#	80# ms [>300 ns]			5/2+#
^112Nb	41	71	111.95083(75)#	60# ms [>300 ns]			2+#
^113Nb	41	72	112.95470(86)#	30# ms [>300 ns]			5/2+#

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. # – 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
   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.

Niobium-92

Niobium-92 is an extinct radionuclide[2] 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.[2][3] This isotope, along with ⁹⁴Nb, has been detected in refined samples of terrestrial niobium and may originate from bombardment by cosmic ray muons in Earth's crust.[4]

References

1. Meija, Juris; 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. 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. arXiv:1602.00966. Bibcode:2016E&PSL.439..172I. doi:10.1016/j.epsl.2016.02.005.
3. Hibiya, Y; Iizuka, T; Enomoto, H (2019). THE INITIAL ABUNDANCE OF NIOBIUM-92 IN THE OUTER SOLAR SYSTEM (PDF). Lunar and Planetary Science Conference (50th ed.). Retrieved 7 September 2019.
4. 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.

• 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. Lay summary.
• 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.