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Natural hafnium (72Hf) 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 years. 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.

Main isotopes of hafnium (72Hf)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
172Hf syn 1.87 y ε 172Lu
174Hf 0.16% 2×1015 y α 170Yb
176Hf 5.26% stable
177Hf 18.60% stable
178Hf 27.28% stable
178m2Hf syn 31 y IT 178Hf
179Hf 13.62% stable
180Hf 35.08% stable
182Hf syn 8.9×106 y β 182Ta
Standard atomic weight Ar, standard(Hf)

List of isotopesEdit

Nuclide
[n 1]
Z N Isotopic mass (u)
[n 2][n 3]
Half-life
[n 4][n 5]
Decay
mode

[n 6]
Daughter
isotope

[n 7]
Spin and
parity
[n 8][n 5]
Natural abundance (mole fraction)
Excitation energy[n 5] Normal proportion Range of variation
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 9] 72 102 173.940046(3) 2.0(4)×1015 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 10] 72 104 175.9414086(24) Observationally Stable[n 11] 0+ 0.0526(7) 0.05206–0.05271
177Hf 72 105 176.9432207(23) Observationally Stable[n 12] 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 13] 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 14] 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 15] 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 72 110 181.950554(7) 8.90(9)×106 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. ^ 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. ^ a b c # – 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. ^ Used in lutetium-hafnium dating
  11. ^ Believed to undergo α decay to 172Yb
  12. ^ Believed to undergo α decay to 173Yb
  13. ^ Believed to undergo α decay to 174Yb
  14. ^ Believed to undergo α decay to 175Yb
  15. ^ Believed to undergo α decay to 176Yb

ReferencesEdit

  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.