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Isotopes of hafnium

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
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
182Hf synth 8.9×106 y β 182Ta
Standard atomic weight Ar°(Hf)

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.[5]

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.

  1. ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ^ a b Belli, P.; Bernabei, R.; Cappella, F.; Caracciolo, V.; Cerulli, R.; Incicchitti, A.; Laubenstein, M.; Leoncini, A.; Merlo, V.; Nagorny, S.S.; Nahorna, V.V.; Nisi, S.; Wang, P. (January 2025). "A new measurement of 174Hf alpha decay". Nuclear Physics A. 1053: 122976. doi:10.1016/j.nuclphysa.2024.122976.
  3. ^ "Standard Atomic Weights: Hafnium". CIAAW. 2019.
  4. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  5. ^ Kleine T, Walker RJ (August 2017). "Tungsten Isotopes in Planets". Annual Review of Earth and Planetary Sciences. 45 (1): 389–417. Bibcode:2017AREPS..45..389K. doi:10.1146/annurev-earth-063016-020037. PMC 6398955. PMID 30842690.

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