Isotopes of hafnium

Isotopes of hafnium (72Hf)
Main isotopes Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
172Hf synth 1.87 y ε 172Lu
174Hf 0.16% 3.8×1016 y α 170Yb
175Hf synth 69.90 d 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)

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. 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.

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.

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