Isotopes of hafnium

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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] The next most stable radioisotope is 182Hf with a half-life of 8.90 million years, an extinct radionuclide used in hafnium–tungsten dating to study the chronology of planetary differentiation.[6]

Quick facts Main isotopes, Decay ...
Isotopes of hafnium (72Hf)
Main isotopes[1] Decay
Isotope 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 8.90×106 y β− 182Ta
Standard atomic weight Ar°(Hf)
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Other isotopes have been synthesized running from 153Hf to 192Hf, but none of the 33 others has a half-life over 1.87 years, and most have half-lives under five minutes. There are also at least 41 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


More information Nuclide, Z ...
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:
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  1. [1]
    mHf – Excited nuclear isomer.
  2. [2]
    ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. [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]
    Bold half-life – nearly stable, half-life longer than age of universe.
  5. [5]
    # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  6. [6]
    Modes of decay:
    EC:Electron capture
    IT:Isomeric transition
  7. [7]
    Bold symbol as daughter – Daughter product is stable.
  8. [8]
    ( ) spin value – Indicates spin with weak assignment arguments.
  9. [9]
    primordial radionuclide
  10. [10]
    Theorized to also undergo β+β+ decay to 174Yb
  11. [11]
    Used in lutetium-hafnium dating
  12. [12]
    Believed to undergo α decay to 172Yb
  13. [13]
    Believed to undergo α decay to 173Yb with a half-life over 1.3×1018 y.
  14. [14]
    Believed to undergo α decay to 174Yb
  15. [15]
    Believed to undergo α decay to 175Yb
  16. [16]
    Believed to undergo α decay to 176Yb
  17. [17]
    Extinct radionuclide, used in hafnium–tungsten dating[6]

See also

Daughter products other than hafnium

References

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