Isotopes of hafnium

Summary

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. 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.

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°(Hf)
  • 178.486±0.006
  • 178.49±0.01 (abridged)[1][2]

List of isotopesEdit

Nuclide
[n 1]
Z N Isotopic mass (Da)
[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+
This table header & footer:
  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. ^ "Standard Atomic Weights: Hafnium". CIAAW. 2019.
  2. ^ 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.
  • 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.
  • "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
  • Half-life, spin, and isomer data selected from the following sources.