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 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.
List of isotopes
|-id=Hafnium-152 | 152Hf | style="text-align:right" | 72 | style="text-align:right" | 80 | | style="text-align:center" | 2026
|-id=Hafnium-153 | 153Hf | style="text-align:right" | 72 | style="text-align:right" | 81 | 152.970692(322)# | style="text-align:center" | 2026 | 400# ms[>200 ns] | β+? | 153Lu | 1/2+#
|-id=Hafnium-154 | rowspan=2|154Hf | rowspan=2 style="text-align:right" | 72 | rowspan=2 style="text-align:right" | 82 | rowspan=2|153.96486(32)# | rowspan=2 style="text-align:center" | 1981 | rowspan=2|2(1) s | β+ | 154Lu | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (rare) | 150Yb |-id=Hafnium-154m | style="text-indent:1em" | 154mHf | colspan="3" style="text-indent:2em" | 2721(50)# keV | style="text-align:center" | 1989 | 9(4) μs | IT | 154Hf | (10+)
|-id=Hafnium-155 | 155Hf | style="text-align:right" | 72 | style="text-align:right" | 83 | 154.96317(32)# | style="text-align:center" | 1981 | 843(30) ms | β+ | 155Lu | 7/2−#
|-id=Hafnium-155m | style="text-indent:1em" | 155mHf | colspan="3" style="text-indent:2em" | 2.5815(10) keV | style="text-align:center" | 2024 | 510(30) ns | IT | 155Hf | 27/2-#
|-id=Hafnium-156 | 156Hf | style="text-align:right" | 72 | style="text-align:right" | 84 | 155.95940(16) | style="text-align:center" | 1979 | 23(1) ms | α | 152Yb | 0+
|-id=Hafnium-156m | style="text-indent:1em" | 156mHf | colspan="3" style="text-indent:2em" | 1958.8(10) keV | style="text-align:center" | 1989 | 480(40) μs | α | 152Yb | (8+)
|-id=Hafnium-157 | rowspan=2|157Hf | rowspan=2 style="text-align:right" | 72 | rowspan=2 style="text-align:right" | 85 | rowspan=2|156.95829(22)# | rowspan=2 style="text-align:center" | 1965 | rowspan=2|115(1) ms | α (94%) | 153Yb | rowspan=2|7/2− | rowspan=2| | rowspan=2| |- | β+ (6%) | 157Lu |-id=Hafnium-158 | rowspan=2|158Hf | rowspan=2 style="text-align:right" | 72 | rowspan=2 style="text-align:right" | 86 | rowspan=2|157.954801(19) | rowspan=2 style="text-align:center" | 1965 | rowspan=2|2.85(7) s | β+ (55.7%) | 158Lu | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (44.3%) | 154Yb |-id=Hafnium-159 | rowspan=2|159Hf | rowspan=2 style="text-align:right" | 72 | rowspan=2 style="text-align:right" | 87 | rowspan=2|158.953996(18) | rowspan=2 style="text-align:center" | 1973 | rowspan=2|5.20(10) s | β+ (65%) | 159Lu | rowspan=2|7/2− | rowspan=2| | rowspan=2| |- | α (35%) | 155Yb |-id=Hafnium-160 | rowspan=2|160Hf | rowspan=2 style="text-align:right" | 72 | rowspan=2 style="text-align:right" | 88 | rowspan=2|159.950683(10) | rowspan=2 style="text-align:center" | 1973 | rowspan=2|13.6(2) s | β+ (99.3%) | 160Lu | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (0.7%) | 156Yb |-id=Hafnium-161 | rowspan=2|161Hf | rowspan=2 style="text-align:right" | 72 | rowspan=2 style="text-align:right" | 89 | rowspan=2|160.950278(25) | rowspan=2 style="text-align:center" | 1973 | rowspan=2|18.4(4) s | β+ (99.71%) | 161Lu | rowspan=2|(7/2−) | rowspan=2| | rowspan=2| |- | α (0.29%) | 157Yb |-id=Hafnium-161m | style="text-indent:1em" | 161mHf | colspan="3" style="text-indent:2em" | 329.0(5) keV | style="text-align:center" | 2014 | 4.8(2) μs | IT | 161Hf | (13/2+)
|-id=Hafnium-162 | rowspan=2|162Hf | rowspan=2 style="text-align:right" | 72 | rowspan=2 style="text-align:right" | 90 | rowspan=2|161.9472155(96) | rowspan=2 style="text-align:center" | 1982 | rowspan=2|39.4(9) s | β+ (99.99%) | 162Lu | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (0.008%) | 158Yb |-id=Hafnium-163 | 163Hf | style="text-align:right" | 72 | style="text-align:right" | 91 | 162.947107(28) | style="text-align:center" | 1982 | 40.0(6) s | β+ | 163Lu | (5/2−)
|-id=Hafnium-164 | 164Hf | style="text-align:right" | 72 | style="text-align:right" | 92 | 163.944371(17) | style="text-align:center" | 1981 | 111(8) s | β+ | 164Lu | 0+
|-id=Hafnium-165 | 165Hf | style="text-align:right" | 72 | style="text-align:right" | 93 | 164.944567(30) | style="text-align:center" | 1981 | 76(4) s | β+ | 165Lu | (5/2−)
|-id=Hafnium-166 | 166Hf | style="text-align:right" | 72 | style="text-align:right" | 94 | 165.942180(30) | style="text-align:center" | 1965 | 6.77(30) min | β+ | 166Lu | 0+
|-id=Hafnium-167 | 167Hf | style="text-align:right" | 72 | style="text-align:right" | 95 | 166.942600(30) | style="text-align:center" | 1969 | 2.05(5) min | β+ | 167Lu | (5/2)−
|-id=Hafnium-168 | rowspan=2|168Hf | rowspan=2 style="text-align:right" | 72 | rowspan=2 style="text-align:right" | 96 | rowspan=2|167.940568(30) | rowspan=2 style="text-align:center" | 1961 | rowspan=2|25.95(20) min | EC (98%) | 168Lu | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β+ (2%) | 168Lu |-id=Hafnium-169 | 169Hf | style="text-align:right" | 72 | style="text-align:right" | 97 | 168.941259(30) | style="text-align:center" | 1969 | 3.24(4) min | β+ | 169Lu | (5/2−)
|-id=Hafnium-170 | 170Hf | style="text-align:right" | 72 | style="text-align:right" | 98 | 169.939609(30) | style="text-align:center" | 1961 | 16.01(13) h | EC | 170Lu | 0+
|-id=Hafnium-171 | 171Hf | style="text-align:right" | 72 | style="text-align:right" | 99 | 170.940492(31) | style="text-align:center" | 1951 | 12.1(4) h | β+ | 171Lu | 7/2+
|-id=Hafnium-171m | style="text-indent:1em" | 171mHf | colspan="3" style="text-indent:2em" | 21.93(9) keV | style="text-align:center" | 1997 | 29.5(9) s | IT | 171Hf | 1/2−
|-id=Hafnium-172 | 172Hf | style="text-align:right" | 72 | style="text-align:right" | 100 | 171.939450(26) | style="text-align:center" | 1951 | 1.87(3) y | EC | 172Lu | 0+
|-id=Hafnium-172m | style="text-indent:1em" | 172mHf | colspan="3" style="text-indent:2em" | 2005.84(11) keV | style="text-align:center" | 1977 | 163(3) ns | IT | 172Hf | (8−)
|-id=Hafnium-173 | 173Hf | style="text-align:right" | 72 | style="text-align:right" | 101 | 172.940513(30) | style="text-align:center" | 1951 | 23.6(1) h | β+ | 173Lu | 1/2−
|-id=Hafnium-173m1 | style="text-indent:1em" | 173m1Hf | colspan="3" style="text-indent:2em" | 107.16(5) keV | style="text-align:center" | 1973 | 180(8) ns | IT | 173Hf | 5/2−
|-id=Hafnium-173m2 | style="text-indent:1em" | 173m2Hf | colspan="3" style="text-indent:2em" | 197.47(10) keV | style="text-align:center" | 1973 | 160(40) ns | IT | 173Hf | 7/2+
|-id=Hafnium-174 | 174Hfprimordial radionuclide | style="text-align:right" | 72 | style="text-align:right" | 102 | 173.9400484(24) | style="text-align:center" | 1939 | | αTheorized to also undergo β+β+ decay to 174Yb | 170Yb | 0+ | 0.0016(12) | |-id=Hafnium-174m1 | style="text-indent:1em" | 174m1Hf | colspan="3" style="text-indent:2em" | 1549.26(4) keV | style="text-align:center" | 1973 | 138(4) ns | IT | 174Hf | 6+
|-id=Hafnium-174m2 | style="text-indent:1em" | 174m2Hf | colspan="3" style="text-indent:2em" | 1797.59(7) keV | style="text-align:center" | 1990 | 2.39(4) μs | IT | 174Hf | 8−
|-id=Hafnium-174m3 | style="text-indent:1em" | 174m3Hf | colspan="3" style="text-indent:2em" | 3312.07(6) keV | style="text-align:center" | 1990 | 3.7(2) μs | IT | 174Hf | 14+
|-id=Hafnium-175 | 175Hf | style="text-align:right" | 72 | style="text-align:right" | 103 | 174.9415114(25) | style="text-align:center" | 1949 | 69.90(7) d | EC | 175Lu | 5/2−
|-id=Hafnium-175m1 | style="text-indent:1em" | 175m1Hf | colspan="3" style="text-indent:2em" | 125.89(12) keV | style="text-align:center" | 1964 | 53.7(15) μs | IT | 175Hf | 1/2−
|-id=Hafnium-175m2 | style="text-indent:1em" | 175m2Hf | colspan="3" style="text-indent:2em" | 1433.41(12) keV | style="text-align:center" | 1980 | 1.10(8) μs | IT | 175Hf | 19/2+
|-id=Hafnium-175m3 | style="text-indent:1em" | 175m3Hf | colspan="3" style="text-indent:2em" | 3015.6(4) keV | style="text-align:center" | 1980 | 1.21(15) μs | IT | 175Hf | 35/2−
|-id=Hafnium-175m4 | style="text-indent:1em" | 175m4Hf | colspan="3" style="text-indent:2em" | 4636.2(12) keV | style="text-align:center" | 1990 | 1.9(1) μs | IT | 175Hf | 45/2+
|-id=Hafnium-176 | 176HfUsed in lutetium-hafnium dating | style="text-align:right" | 72 | style="text-align:right" | 104 | 175.9414098(16) | style="text-align:center" | 1934 | colspan=3 align=center|Observationally StableBelieved to undergo α decay to 172Yb | 0+ | 0.0526(70) | |-id=Hafnium-176m1 | style="text-indent:1em" | 176m1Hf | colspan="3" style="text-indent:2em" | 1333.07(7) keV | style="text-align:center" | 1964 | 9.6(3) μs | IT | 176Hf | 6+
|-id=Hafnium-176m2 | style="text-indent:1em" | 176m2Hf | colspan="3" style="text-indent:2em" | 1559.31(9) keV | style="text-align:center" | 1967 | 9.9(2) μs | IT | 176Hf | 8−
|-id=Hafnium-176m3 | style="text-indent:1em" | 176m3Hf | colspan="3" style="text-indent:2em" | 2865.8(7) keV | style="text-align:center" | 1975 | 401(6) μs | IT | 176Hf | 14−
|-id=Hafnium-176m4 | style="text-indent:1em" | 176m4Hf | colspan="3" style="text-indent:2em" | 4863.6(9) keV | style="text-align:center" | 1976 | 43(4) μs | IT | 176Hf | 22−
|-id=Hafnium-177 | 177Hf | style="text-align:right" | 72 | style="text-align:right" | 105 | 176.9432302(15) | style="text-align:center" | 1934 | colspan=3 align=center|Observationally StableBelieved to undergo α decay to 173Yb with a half-life over 1.3×1018 y. | 7/2− | 0.1860(16) | |-id=Hafnium-177m1 | style="text-indent:1em" | 177m1Hf | colspan="3" style="text-indent:2em" | 1315.4502(8) keV | style="text-align:center" | 1966 | 1.09(5) s | IT | 177Hf | 23/2+
|-id=Hafnium-177m2 | style="text-indent:1em" | 177m2Hf | colspan="3" style="text-indent:2em" | 1342.4(10) keV | style="text-align:center" | 1998 | 55.9(12) μs | IT | 177Hf | (19/2−)
|-id=Hafnium-177m3 | style="text-indent:1em" | 177m3Hf | colspan="3" style="text-indent:2em" | 2740.02(15) keV | style="text-align:center" | 1971 | 51.4(5) min | IT | 177Hf | 37/2−
|-id=Hafnium-178 | 178Hf | style="text-align:right" | 72 | style="text-align:right" | 106 | 177.9437083(15) | style="text-align:center" | 1934 | colspan=3 align=center|Observationally StableBelieved to undergo α decay to 174Yb | 0+ | 0.2728(28) | |-id=Hafnium-178m1 | style="text-indent:1em" | 178m1Hf | colspan="3" style="text-indent:2em" | 1147.416(6) keV | style="text-align:center" | 1958 | 4.0(2) s | IT | 178Hf | 8−
|-id=Hafnium-178m2 | style="text-indent:1em" | 178m2Hf | colspan="3" style="text-indent:2em" | 2446.09(8) keV | style="text-align:center" | 1968 | 31(1) y | IT | 178Hf | 16+
|-id=Hafnium-178m3 | style="text-indent:1em" | 178m3Hf | colspan="3" style="text-indent:2em" | 2572.4(3) keV | style="text-align:center" | 1977 | 68(2) μs | IT | 178Hf | 14−
|-id=Hafnium-179 | 179Hf | style="text-align:right" | 72 | style="text-align:right" | 107 | 178.9458257(15) | style="text-align:center" | 1934 | colspan=3 align=center|Observationally StableBelieved to undergo α decay to 175Yb | 9/2+ | 0.1362(11) | |-id=Hafnium-179m1 | style="text-indent:1em" | 179m1Hf | colspan="3" style="text-indent:2em" | 375.0352(25) keV | style="text-align:center" | 1951 | 18.67(4) s | IT | 179Hf | 1/2−
|-id=Hafnium-179m2 | style="text-indent:1em" | 179m2Hf | colspan="3" style="text-indent:2em" | 1106.412(33) keV | style="text-align:center" | 1970 | 25.00(17) d | IT | 179Hf | 25/2−
|-id=Hafnium-179m3 | style="text-indent:1em" | 179m3Hf