Isotopes of hafnium

Natural hafnium (Hf) consists of five stable isotopes (¹⁷⁶Hf, ¹⁷⁷Hf, ¹⁷⁸Hf, ¹⁷⁹Hf, and ¹⁸⁰Hf) and one very long-lived radioisotope, ¹⁷⁴Hf, with a half-life of 2×10¹⁵ years. In addition, there are 30 other known radionuclides, the most stable of which is ¹⁸²Hf with a half-life of 8.9×10⁶ years. No other radioisotope has a half-life over 1.87 days. Most isotopes have half-lives under 1 minute. There are also 26 known nuclear isomers, the most stable of which is ^178m2Hf with a half-life of 31 years.

Relative atomic mass: 178.49(2).

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life[n 1]	decay mode(s)[1][n 2]	daughter isotope(s)[n 3]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^153Hf	72	81	152.97069(54)#	400# ms [>200 ns]			1/2+#
^153mHf	750(100)# keV			500# ms			11/2−#
^154Hf	72	82	153.96486(54)#	2(1) s	β^+	^154Lu	0+
					α (rare)	^150Yb
^155Hf	72	83	154.96339(43)#	890(120) ms	β^+	^155Lu	7/2−#
					α (rare)	^151Yb
^156Hf	72	84	155.95936(22)	23(1) ms	α (97%)	^152Yb	0+
					β^+ (3%)	^156Lu
^156mHf	1959.0(10) keV			480(40) µs			8+
^157Hf	72	85	156.95840(21)#	115(1) ms	α (86%)	^153Yb	7/2−
					β^+ (14%)	^157Lu
^158Hf	72	86	157.954799(19)	2.84(7) s	β^+ (55%)	^158Lu	0+
					α (45%)	^154Yb
^159Hf	72	87	158.953995(18)	5.20(10) s	β^+ (59%)	^159Lu	7/2−#
					α (41%)	^155Yb
^160Hf	72	88	159.950684(12)	13.6(2) s	β^+ (99.3%)	^160Lu	0+
					α (.7%)	^156Yb
^161Hf	72	89	160.950275(24)	18.2(5) s	β^+ (99.7%)	^161Lu	3/2−#
					α (.3%)	^157Yb
^162Hf	72	90	161.94721(1)	39.4(9) s	β^+ (99.99%)	^162Lu	0+
					α (.008%)	^158Yb
^163Hf	72	91	162.94709(3)	40.0(6) s	β^+	^163Lu	3/2−#
					α (10^−4%)	^159Yb
^164Hf	72	92	163.944367(22)	111(8) s	β^+	^164Lu	0+
^165Hf	72	93	164.94457(3)	76(4) s	β^+	^165Lu	(5/2−)
^166Hf	72	94	165.94218(3)	6.77(30) min	β^+	^166Lu	0+
^167Hf	72	95	166.94260(3)	2.05(5) min	β^+	^167Lu	(5/2)−
^168Hf	72	96	167.94057(3)	25.95(20) min	β^+	^168Lu	0+
^169Hf	72	97	168.94126(3)	3.24(4) min	β^+	^169Lu	(5/2)−
^170Hf	72	98	169.93961(3)	16.01(13) h	EC	^170Lu	0+
^171Hf	72	99	170.94049(3)	12.1(4) h	β^+	^171Lu	7/2(+)
^171mHf	21.93(9) keV			29.5(9) s	IT	^171Hf	1/2(−)
^172Hf	72	100	171.939448(26)	1.87(3) y	EC	^172Lu	0+
^172mHf	2005.58(11) keV			163(3) ns			(8−)
^173Hf	72	101	172.94051(3)	23.6(1) h	β^+	^173Lu	1/2−
^174Hf[n 4]	72	102	173.940046(3)	2.0(4)×10^15 y	α	^170Yb	0+	0.0016(1)	0.001619–0.001621
^174m1Hf	1549.3 keV			138(4) ns			(6+)
^174m2Hf	1797.5(20) keV			2.39(4) µs			(8−)
^174m3Hf	3311.7 keV			3.7(2) µs			(14+)
^175Hf	72	103	174.941509(3)	70(2) d	β^+	^175Lu	5/2−
^176Hf[n 5]	72	104	175.9414086(24)	Observationally Stable[n 6]			0+	0.0526(7)	0.05206–0.05271
^177Hf	72	105	176.9432207(23)	Observationally Stable[n 7]			7/2−	0.1860(9)	0.18593–0.18606
^177m1Hf	1315.4504(8) keV			1.09(5) s			23/2+
^177m2Hf	1342.38(20) keV			55.9(12) µs			(19/2−)
^177m3Hf	2740.02(15) keV			51.4(5) min			37/2−
^178Hf	72	106	177.9436988(23)	Observationally Stable[n 8]			0+	0.2728(7)	0.27278–0.27297
^178m1Hf	1147.423(5) keV			4.0(2) s			8−
^178m2Hf	2445.69(11) keV			31(1) y			16+
^178m3Hf	2573.5(5) keV			68(2) µs			(14−)
^179Hf	72	107	178.9458161(23)	Observationally Stable[n 9]			9/2+	0.1362(2)	0.13619–0.1363
^179m1Hf	375.0367(25) keV			18.67(4) s			1/2−
^179m2Hf	1105.84(19) keV			25.05(25) d			25/2−
^180Hf	72	108	179.9465500(23)	Observationally Stable[n 10]			0+	0.3508(16)	0.35076–0.351
^180m1Hf	1141.48(4) keV			5.47(4) h			8−
^180m2Hf	1374.15(4) keV			0.57(2) µs			(4−)
^180m3Hf	2425.8(10) keV			15(5) µs			(10+)
^180m4Hf	2486.3(9) keV			10(1) µs			12+
^180m5Hf	2538.3(12) keV			>10 µs			(14+)
^180m6Hf	3599.3(18) keV			90(10) µs			(18−)
^181Hf	72	109	180.9491012(23)	42.39(6) d	β^−	^181Ta	1/2−
^181m1Hf	595(3) keV			80(5) µs			(9/2+)
^181m2Hf	1040(10) keV			~100 µs			(17/2+)
^181m3Hf	1738(10) keV			1.5(5) ms			(27/2−)
^182Hf[n 11]	72	110	181.950554(7)	8.90(9)×10^6 y	β^−	^182Ta	0+
^182mHf	1172.88(18) keV			61.5(15) min	β^− (58%)	^182Ta	8−
					IT (42%)	^182Hf
^183Hf	72	111	182.95353(3)	1.067(17) h	β^−	^183Ta	(3/2−)
^184Hf	72	112	183.95545(4)	4.12(5) h	β^−	^184Ta	0+
^184mHf	1272.4(4) keV			48(10) s	β^−	^184Ta	8−
^185Hf	72	113	184.95882(21)#	3.5(6) min	β^−	^185Ta	3/2−#
^186Hf	72	114	185.96089(32)#	2.6(12) min	β^−	^186Ta	0+
^187Hf	72	115	186.96459(43)#	30# s [>300 ns]
^188Hf	72	116	187.96685(54)#	20# s [>300 ns]			0+

1. Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
2. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
3. Bold for stable isotopes
4. primordial radionuclide
5. Used in Lutetium-Hafnium dating
6. Believed to undergo α decay to ¹⁷²Yb
7. Believed to undergo α decay to ¹⁷³Yb
8. Believed to undergo α decay to ¹⁷⁴Yb
9. Believed to undergo α decay to ¹⁷⁵Yb
10. Believed to undergo α decay to ¹⁷⁶Yb
11. Believed to occur naturally after the α decay of ¹⁸⁶W (which is currently classified as stable)

Notes

• Evaluated isotopic composition is for most but not all commercial samples.
• 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

1. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). 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:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683.
  • M. E. Wieser (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. See editing notes on this article's talk page.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.