Isotopes of hafnium

Natural hafnium (₇₂Hf) consists of five observationally stable isotopes (¹⁷⁶Hf, ¹⁷⁷Hf, ¹⁷⁸Hf, ¹⁷⁹Hf, and ¹⁸⁰Hf) and one very long-lived radioisotope, ¹⁷⁴Hf, with a half-life of 3.8×10¹⁶ years.^[2] In addition, there are 34 known synthetic radioisotopes, the most stable of which is ¹⁸²Hf with a half-life of 8.9×10⁶ years. This extinct radionuclide is used in hafnium–tungsten dating to study the chronology of planetary differentiation.^[6]

Isotopes of hafnium (₇₂Hf)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 172Hf synth 1.87 y ε 172Lu 174Hf 0.16% 3.8×1016 y[2] α 170Yb 175Hf synth 69.90 d[3] ε 175Lu 176Hf 5.26% stable 177Hf 18.6% stable 178Hf 27.3% stable 178m2Hf synth 31 y IT 178Hf 179Hf 13.6% stable 180Hf 35.1% stable 181Hf synth 42.39 d β− 181Ta 182Hf synth 8.9×106 y β− 182Ta
Standard atomic weight Ar°(Hf)
	178.486±0.006[4] 178.49±0.01 (abridged)[5]
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No other radioisotope has a half-life over 1.87 years. Most isotopes have half-lives under 1 minute. There are also at least 27 nuclear isomers, the most stable of which is ^178m2Hf with a half-life of 31 years. All isotopes of hafnium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da)[7] [n 2][n 3]	Half-life[1] [n 4][n 5]	Decay mode[1] [n 6]	Daughter isotope [n 7]	Spin and parity[1] [n 8][n 5]	Natural abundance (mole fraction)
	Excitation energy[n 5]							Normal proportion[1]	Range of variation
153Hf	72	81	152.97069(32)#	400# ms [>200 ns]			1/2+#
154Hf	72	82	153.96486(32)#	2(1) s	β+	154Lu	0+
					α (rare)	150Yb
154mHf	2721(50)# keV			9(4) μs	IT	154Hf	(10+)
155Hf	72	83	154.96317(32)#	843(30) ms	β+	155Lu	7/2−#
156Hf	72	84	155.95940(16)	23(1) ms	α	152Yb	0+
156mHf	1958.8(10) keV			480(40) μs	α	152Yb	(8+)
157Hf	72	85	156.95829(22)#	115(1) ms	α (94%)	153Yb	7/2−
					β+ (6%)	157Lu
158Hf	72	86	157.954801(19)	2.85(7) s	β+ (55.7%)	158Lu	0+
					α (44.3%)	154Yb
159Hf	72	87	158.953996(18)	5.20(10) s	β+ (65%)	159Lu	7/2−
					α (35%)	155Yb
160Hf	72	88	159.950683(10)	13.6(2) s	β+ (99.3%)	160Lu	0+
					α (0.7%)	156Yb
161Hf	72	89	160.950278(25)	18.4(4) s	β+ (99.71%)	161Lu	(7/2−)
					α (0.29%)	157Yb
161mHf	329.0(5) keV			4.8(2) μs	IT	161Hf	(13/2+)
162Hf	72	90	161.9472155(96)	39.4(9) s	β+ (99.99%)	162Lu	0+
					α (0.008%)	158Yb
163Hf	72	91	162.947107(28)	40.0(6) s	β+	163Lu	(5/2−)
164Hf	72	92	163.944371(17)	111(8) s	β+	164Lu	0+
165Hf	72	93	164.944567(30)	76(4) s	β+	165Lu	(5/2−)
166Hf	72	94	165.942180(30)	6.77(30) min	β+	166Lu	0+
167Hf	72	95	166.942600(30)	2.05(5) min	β+	167Lu	(5/2)−
168Hf	72	96	167.940568(30)	25.95(20) min	EC (98%)	168Lu	0+
					β+ (2%)	168Lu
169Hf	72	97	168.941259(30)	3.24(4) min	β+	169Lu	(5/2−)
170Hf	72	98	169.939609(30)	16.01(13) h	EC	170Lu	0+
171Hf	72	99	170.940492(31)	12.1(4) h	β+	171Lu	7/2+
171mHf	21.93(9) keV			29.5(9) s	IT	171Hf	1/2−
172Hf	72	100	171.939450(26)	1.87(3) y	EC	172Lu	0+
172mHf	2005.84(11) keV			163(3) ns	IT	172Hf	(8−)
173Hf	72	101	172.940513(30)	23.6(1) h	β+	173Lu	1/2−
173m1Hf	107.16(5) keV			180(8) ns	IT	173Hf	5/2−
173m2Hf	197.47(10) keV			160(40) ns	IT	173Hf	7/2+
174Hf[n 9]	72	102	173.9400484(24)	3.8+1.7 −0.9×1016 y[2]	α[n 10]	170Yb	0+	0.0016(12)
174m1Hf	1549.26(4) keV			138(4) ns	IT	174Hf	6+
174m2Hf	1797.59(7) keV			2.39(4) μs	IT	174Hf	8−
174m3Hf	3312.07(6) keV			3.7(2) μs	IT	174Hf	14+
175Hf	72	103	174.9415114(25)	69.90(7) d[3]	EC	175Lu	5/2−
175m1Hf	125.89(12) keV			53.7(15) μs	IT	175Hf	1/2−
175m2Hf	1433.41(12) keV			1.10(8) μs	IT	175Hf	19/2+
175m3Hf	3015.6(4) keV			1.21(15) μs	IT	175Hf	35/2−
175m4Hf	4636.2(12) keV			1.9(1) μs	IT	175Hf	45/2+
176Hf[n 11]	72	104	175.9414098(16)	Observationally Stable[n 12]			0+	0.0526(70)
176m1Hf	1333.07(7) keV			9.6(3) μs	IT	176Hf	6+
176m2Hf	1559.31(9) keV			9.9(2) μs	IT	176Hf	8−
176m3Hf	2865.8(7) keV			401(6) μs	IT	176Hf	14−
176m4Hf	4863.6(9) keV			43(4) μs	IT	176Hf	22−
177Hf	72	105	176.9432302(15)	Observationally Stable[n 13]			7/2−	0.1860(16)
177m1Hf	1315.4502(8) keV			1.09(5) s	IT	177Hf	23/2+
177m2Hf	1342.4(10) keV			55.9(12) μs	IT	177Hf	(19/2−)
177m3Hf	2740.02(15) keV			51.4(5) min	IT	177Hf	37/2−
178Hf	72	106	177.9437083(15)	Observationally Stable[n 14]			0+	0.2728(28)
178m1Hf	1147.416(6) keV			4.0(2) s	IT	178Hf	8−
178m2Hf	2446.09(8) keV			31(1) y	IT	178Hf	16+
178m3Hf	2572.4(3) keV			68(2) μs	IT	178Hf	14−
179Hf	72	107	178.9458257(15)	Observationally Stable[n 15]			9/2+	0.1362(11)
179m1Hf	375.0352(25) keV			18.67(4) s	IT	179Hf	1/2−
179m2Hf	1106.412(33) keV			25.00(17) d	IT	179Hf	25/2−
179m3Hf	3775.2(21) keV			15(5) μs	IT	179Hf	(43/2+)
180Hf	72	108	179.9465595(15)	Observationally Stable[n 16]			0+	0.3508(33)
180m1Hf	1141.552(15) keV			5.53(2) h	IT (99.69%)	180Hf	8−
					β− (0.31%)	180m1Ta[8]
180m2Hf	1374.36(4) keV			570(20) μs	IT	180Hf	4−
180m3Hf	2485.5(5) keV			0.94(11) μs	IT	180Hf	12+
180m4Hf	3599.0(10) keV			90(10) μs	IT	180Hf	(18−)
181Hf	72	109	180.9491108(15)	42.39(6) d	β−	181Ta	1/2−
181m1Hf	595.27(4) keV			80(5) μs	IT	181Hf	(9/2+)
181m2Hf	1043.5(8) keV			~100 μs	IT	181Hf	(17/2+)
181m3Hf	1741.9(13) keV			1.5(5) ms	IT	181Hf	(25/2−)
182Hf[n 17]	72	110	181.9505637(66)	8.90(9)×106 y	β−	182Ta	0+
182m1Hf	1172.87(18) keV			61.5(15) min	β− (54%)	182Ta	8−
					IT (46%)	182Hf
182m2Hf	2571.3(12) keV			40(10) μs	IT	182Hf	(13+)
183Hf	72	111	182.953533(32)	1.018(2) h	β−	183Ta	(3/2−)
183mHf	1464(64) keV			40(30) s	IT	183Hf	27/2−#
184Hf	72	112	183.955449(43)	4.12(5) h	β−	184Ta	0+
184m1Hf	1272.2(4) keV			48(10) s	IT	184Hf	8−
184m2Hf	2477(10) keV			16(7) min			15+#
185Hf	72	113	184.958862(69)	3.5(6) min	β−	185Ta	(9/2−)
186Hf	72	114	185.960897(55)	2.6(12) min	β−	186Ta	0+
186mHf	2968(43) keV			>20 s			17+#
187Hf	72	115	186.96457(22)#	14# s [>300 ns]			9/2−#
187mHf	500(300)# keV			270(80) ns	IT	187Hf	3/2−#
188Hf	72	116	187.96690(32)#	7# s [>300 ns]			0+
189Hf	72	117	188.97085(32)#	400# ms [>300 ns]			3/2−#
190Hf	72	118	189.97338(43)#	600# ms [>300 ns]			0+
191Hf[9]	72	119
192Hf[9]	72	120					0+
This table header & footer: view

1. ^mHf – 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. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition

7. Bold symbol as daughter – Daughter product is stable.
8. ( ) spin value – Indicates spin with weak assignment arguments.
9. primordial radionuclide
10. Theorized to also undergo β⁺β⁺ decay to ¹⁷⁴Yb
11. Used in lutetium-hafnium dating
12. Believed to undergo α decay to ¹⁷²Yb
13. Believed to undergo α decay to ¹⁷³Yb with a half-life over 1.3×10¹⁸ y.
14. Believed to undergo α decay to ¹⁷⁴Yb
15. Believed to undergo α decay to ¹⁷⁵Yb
16. Believed to undergo α decay to ¹⁷⁶Yb
17. Extinct radionuclide, used in hafnium–tungsten dating^[6]

See also

Daughter products other than hafnium

• Isotopes of tantalum
• Isotopes of lutetium
• Isotopes of ytterbium