Isotopes of erbium

Naturally occurring erbium (68Er) is composed of six stable isotopes, with 166Er being the most abundant (33.503% natural abundance). Thirty-nine radioisotopes have been characterized with between 74 and 112 neutrons, or 142 to 180 nucleons, with the most stable being 169Er with a half-life of 9.4 days, 172Er with a half-life of 49.3 hours, 160Er with a half-life of 28.58 hours, 165Er with a half-life of 10.36 hours, and 171Er with a half-life of 7.516 hours. All of the remaining radioactive isotopes have half-lives that are less than 3.5 hours, and the majority of these have half-lives that are less than 4 minutes. This element also has numerous meta states, with the most stable being 167mEr (t1/2 2.269 seconds).

The isotopes of erbium range in atomic weight from 141.9723 u (142Er) to 179.9644 u (180Er). The primary decay mode before the most abundant stable isotope, 166Er, is electron capture, and the primary mode after is beta decay. The primary decay products before 166Er are holmium isotopes, and the primary products after are thulium isotopes. All isotopes of erbium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.

List of isotopes

 * 142Er
 * style="text-align:right" | 68
 * style="text-align:right" | 74
 * 141.97002(54)#
 * 10# μs
 * p
 * 141Ho
 * 0+
 * rowspan=2| 143Er
 * style="text-align:right" rowspan=2| 68
 * style="text-align:right" rowspan=2| 75
 * rowspan=2| 142.96655(43)#
 * rowspan=2| 200# ms
 * β+
 * 143Ho
 * rowspan=2|9/2−#
 * rowspan=2|
 * rowspan=2|
 * β+, p
 * 142Dy
 * 144Er
 * style="text-align:right" | 68
 * style="text-align:right" | 76
 * 143.96070(21)#
 * 400# ms [>200 ns]
 * β+
 * 144Ho
 * 0+
 * rowspan=2| 145Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 77
 * rowspan=2| 144.95787(22)#
 * rowspan=2| 900(200) ms
 * β+
 * 145Ho
 * rowspan=2|1/2+#
 * rowspan=2|
 * rowspan=2|
 * β+, p (rare)
 * 144Dy
 * rowspan=3 style="text-indent:1em" | 145mEr
 * rowspan=3 colspan="3" style="text-indent:2em" | 205(4)# keV
 * rowspan=3| 1.0(3) s
 * β+
 * 145Ho
 * rowspan=3| (11/2-)
 * rowspan=3|
 * rowspan=3|
 * IT (rare)
 * 145Er
 * β+, p (rare)
 * 144Dy
 * rowspan=2|146Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 78
 * rowspan=2|145.952418(7)
 * rowspan=2|1.7(6) s
 * β+
 * 146Ho
 * rowspan=2|0+
 * rowspan=2|
 * rowspan=2|
 * β+, p (rare)
 * 145Dy
 * rowspan=2|147Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 79
 * rowspan=2|146.94996(4)#
 * rowspan=2|3.2(1.2) s
 * β+
 * 147Ho
 * rowspan=2|(1/2+)
 * rowspan=2|
 * rowspan=2|
 * β+, p (rare)
 * 146Dy
 * rowspan=2 style="text-indent:1em" | 147mEr
 * rowspan=2 colspan="3" style="text-indent:2em" | 100(50)# keV
 * rowspan=2| 1.6(2) s
 * β+
 * 147Ho
 * rowspan=2| (11/2−)
 * rowspan=2|
 * rowspan=2|
 * β+, p (rare)
 * 146Dy
 * rowspan=2|148Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 80
 * rowspan=2|147.944735(11)#
 * rowspan=2|4.6(2) s
 * β+ (99.85%)
 * 148Ho
 * rowspan=2|0+
 * rowspan=2|
 * rowspan=2|
 * β+, p (.15%)
 * 147Dy
 * style="text-indent:1em" | 148mEr
 * colspan="3" style="text-indent:2em" | 2.9132(4) MeV
 * 13(3) μs
 * IT
 * 148Er
 * (10+)
 * rowspan=2|149Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 81
 * rowspan=2|148.94231(3)
 * rowspan=2|4(2) s
 * β+ (92.8%)
 * 149Ho
 * rowspan=2|(1/2+)
 * rowspan=2|
 * rowspan=2|
 * β+, p (7.2%)
 * 148Dy
 * rowspan=3 style="text-indent:1em" | 149m1Er
 * rowspan=3 colspan="3" style="text-indent:2em" | 741.8(2) keV
 * rowspan=3|8.9(2) s
 * β+ (96.5%)
 * 149Ho
 * rowspan=3|(11/2−)
 * rowspan=3|
 * rowspan=3|
 * IT (3.5%)
 * 149Er
 * β+, p (.18%)
 * 148Dy
 * style="text-indent:1em" | 149m2Er
 * colspan="3" style="text-indent:2em" | 2.6111(3) MeV
 * 0.61(8) μs
 * IT
 * 149Er
 * (19/2+)
 * style="text-indent:1em" | 149m3Er
 * colspan="3" style="text-indent:2em" | 3.302(7) MeV
 * 4.8(1) μs
 * IT
 * 149Er
 * (27/2−)
 * 150Er
 * style="text-align:right" | 68
 * style="text-align:right" | 82
 * 149.937916(18)
 * 18.5(7) s
 * β+
 * 150Ho
 * 0+
 * style="text-indent:1em" | 150mEr
 * colspan="3" style="text-indent:2em" | 2.7965(5) MeV
 * 2.55(10) μs
 * IT
 * 150Er
 * 10+
 * 151Er
 * style="text-align:right" | 68
 * style="text-align:right" | 83
 * 150.937449(18)
 * 23.5(20) s
 * β+
 * 151Ho
 * (7/2−)
 * rowspan=2 style="text-indent:1em" | 151m1Er
 * rowspan=2 colspan="3" style="text-indent:2em" | 2.5860(5) MeV
 * rowspan=2|580(20) ms
 * IT (95.3%)
 * 151Er
 * rowspan=2|(27/2−)
 * rowspan=2|
 * rowspan=2|
 * β+ (4.7%)
 * 151Ho
 * style="text-indent:1em" | 151m2Er
 * colspan="3" style="text-indent:2em" | 10.2866(10) MeV
 * 0.42(5) μs
 * IT
 * 151Er
 * (65/2-, 61/2+)
 * rowspan=2|152Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 84
 * rowspan=2|151.935050(9)
 * rowspan=2|10.3(1) s
 * α (90%)
 * 148Dy
 * rowspan=2|0+
 * rowspan=2|
 * rowspan=2|
 * β+ (10%)
 * 152Ho
 * rowspan=2|153Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 85
 * rowspan=2|152.935086(10)
 * rowspan=2|37.1(2) s
 * α (53%)
 * 149Dy
 * rowspan=2|7/2(−)
 * rowspan=2|
 * rowspan=2|
 * β+ (47%)
 * 153Ho
 * style="text-indent:1em" | 153m1Er
 * colspan="3" style="text-indent:2em" | 2.7982(10) MeV
 * 373(9) ns
 * IT
 * 153Er
 * (27/2-)
 * style="text-indent:1em" | 153m2Er
 * colspan="3" style="text-indent:2em" | 5.2481(10) MeV
 * 248(32) ns
 * IT
 * 153Er
 * (41/2-)
 * rowspan=2|154Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 86
 * rowspan=2|153.932791(5)
 * rowspan=2|3.73(9) min
 * β+ (99.53%)
 * 154Ho
 * rowspan=2|0+
 * rowspan=2|
 * rowspan=2|
 * α (.47%)
 * 150Dy
 * rowspan=2|155Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 87
 * rowspan=2|154.933216(7)
 * rowspan=2|5.3(3) min
 * β+ (99.978%)
 * 155Ho
 * rowspan=2|7/2−
 * rowspan=2|
 * rowspan=2|
 * α (.022%)
 * 151Dy
 * rowspan=2| 156Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 88
 * rowspan=2| 155.931066(26)
 * rowspan=2| 19.5(10) min
 * β+
 * 156Ho
 * rowspan=2| 0+
 * rowspan=2|
 * rowspan=2|
 * α (1.2%)
 * 152Dy
 * 157Er
 * style="text-align:right" | 68
 * style="text-align:right" | 89
 * 156.931923(28)
 * 18.65(10) min
 * β+
 * 157Ho
 * 3/2−
 * style="text-indent:1em" | 157mEr
 * colspan="3" style="text-indent:2em" | 155.4(3) keV
 * 76(6) ms
 * IT
 * 157Er
 * (9/2+)
 * 158Er
 * style="text-align:right" | 68
 * style="text-align:right" | 90
 * 157.929893(27)
 * 2.29(6) h
 * EC
 * 158Ho
 * 0+
 * 159Er
 * style="text-align:right" | 68
 * style="text-align:right" | 91
 * 158.930691(4)
 * 36(1) min
 * β+
 * 159Ho
 * 3/2−
 * style="text-indent:1em" | 159m1Er
 * colspan="3" style="text-indent:2em" | 182.602(24) keV
 * 337(14) ns
 * IT
 * 159Er
 * 9/2+
 * style="text-indent:1em" | 159m2Er
 * colspan="3" style="text-indent:2em" | 429.05(3) keV
 * 590(60) ns
 * IT
 * 159Er
 * 11/2−
 * 160Er
 * style="text-align:right" | 68
 * style="text-align:right" | 92
 * 159.929077(26)
 * 28.58(9) h
 * EC
 * 160Ho
 * 0+
 * 161Er
 * style="text-align:right" | 68
 * style="text-align:right" | 93
 * 160.930004(9)
 * 3.21(3) h
 * β+
 * 161Ho
 * 3/2−
 * style="text-indent:1em" | 161mEr
 * colspan="3" style="text-indent:2em" | 396.44(4) keV
 * 7.5(7) μs
 * IT
 * 161Er
 * 11/2−
 * 162Er
 * style="text-align:right" | 68
 * style="text-align:right" | 94
 * 161. 9287873(8)
 * colspan=3 align=center|Observationally Stable
 * 0+
 * 0.00139(5)
 * style="text-indent:1em" | 162mEr
 * colspan="3" style="text-indent:2em" | 2.02601(13) MeV
 * 88(16) ns
 * IT
 * 162Er
 * (7-)
 * 163Er
 * style="text-align:right" | 68
 * style="text-align:right" | 95
 * 162.930040(5)
 * 75.0(4) min
 * β+
 * 163Ho
 * 5/2−
 * style="text-indent:1em" | 163mEr
 * colspan="3" style="text-indent:2em" | 445.5(6) keV
 * 580(100) ns
 * IT
 * 163Er
 * (11/2−)
 * 164Er
 * style="text-align:right" | 68
 * style="text-align:right" | 96
 * 163.9292077(8)
 * colspan=3 align=center|Observationally Stable '''
 * 0+
 * 0.01601(3)
 * 165Er
 * style="text-align:right" | 68
 * style="text-align:right" | 97
 * 164.9307335(10)
 * 10.36(4) h
 * EC
 * 165Ho
 * 5/2−
 * style="text-indent:1em" | 165m1Er
 * colspan="3" style="text-indent:2em" | 551.3(6) keV
 * 250(30)ns
 * IT
 * 165Er
 * 11/2-
 * style="text-indent:1em" | 165m2Er
 * colspan="3" style="text-indent:2em" | 1.8230(6) MeV
 * 370(40)ns
 * IT
 * 165Er
 * (19/2)
 * 166Er
 * style="text-align:right" | 68
 * style="text-align:right" | 98
 * 165.9303011(4)
 * colspan=3 align=center|Observationally Stable
 * 0+
 * 0.33503(36)
 * 167Er
 * style="text-align:right" | 68
 * style="text-align:right" | 99
 * 166.9320562(3)
 * colspan=3 align=center|Observationally Stable
 * 7/2+
 * 0.22869(9)
 * style="text-indent:1em" | 167mEr
 * colspan="3" style="text-indent:2em" | 207.801(5) keV
 * 2.269(6) s
 * IT
 * 167Er
 * 1/2−
 * 168Er
 * style="text-align:right" | 68
 * style="text-align:right" | 100
 * 167.93237828(28)
 * colspan=3 align=center|Observationally Stable
 * 0+
 * 0.26978(18)
 * style="text-indent:1em" | 168mEr
 * colspan="3" style="text-indent:2em" | 1.0940383(16) MeV
 * 109.0(7) ns
 * IT
 * 168Er
 * 4-
 * 169Er
 * style="text-align:right" | 68
 * style="text-align:right" | 101
 * 168.9345984(3)
 * 9.392(18) d
 * β−
 * 169Tm
 * 1/2−
 * style="text-indent:1em" | 169m1Er
 * colspan="3" style="text-indent:2em" | 92.05(10) keV
 * 285(20) ns
 * IT
 * 169Er
 * (5/2-)
 * style="text-indent:1em" | 169m2Er
 * colspan="3" style="text-indent:2em" | 243.69(17) keV
 * 200(10) ns
 * IT
 * 169Er
 * 7/2+
 * 170Er
 * style="text-align:right" | 68
 * style="text-align:right" | 102
 * 169.9354719(15)
 * colspan=3 align=center|Observationally Stable
 * 0+
 * 0.14910(36)
 * 171Er
 * style="text-align:right" | 68
 * style="text-align:right" | 103
 * 170.93803746(15)
 * 7.516(2) h
 * β−
 * 171Tm
 * 5/2−
 * style="text-indent:1em" | 171mEr
 * colspan="3" style="text-indent:2em" | 198.61(9) keV|
 * 210(10) ns
 * IT
 * 171Er
 * 1/2−
 * 172Er
 * style="text-align:right" | 68
 * style="text-align:right" | 104
 * 171.939363(4)
 * 49.3(5) h
 * β−
 * 172Tm
 * 0+
 * style="text-indent:1em" | 172mEr
 * colspan="3" style="text-indent:2em" | 1.5009(3) MeV
 * 579(62) ns
 * IT
 * 172Er
 * (6+)
 * 173Er
 * style="text-align:right" | 68
 * style="text-align:right" | 105
 * 172.94240(21)#
 * 1.434(17) min
 * β−
 * 173Tm
 * (7/2−)
 * 174Er
 * style="text-align:right" | 68
 * style="text-align:right" | 106
 * 173.94423(32)#
 * 3.2(2) min
 * β−
 * 174Tm
 * 0+
 * style="text-indent:1em" | 174mEr
 * colspan="3" style="text-indent:2em" | 1.1115(7) MeV
 * 3.9(3) s
 * IT
 * 174Er
 * 8-
 * 175Er
 * style="text-align:right" | 68
 * style="text-align:right" | 107
 * 174.94777(43)#
 * 1.2(3) min
 * β−
 * 175Tm
 * 9/2+#
 * 176Er
 * style="text-align:right" | 68
 * style="text-align:right" | 108
 * 175.94994(43)#
 * 12# s (>300 ns)
 * β−
 * 176Tm
 * 0+
 * 177Er
 * style="text-align:right" | 68
 * style="text-align:right" | 109
 * 176.95399(54)#
 * 8# s (>300 ns)
 * β−
 * 177Tm
 * 1/2−#
 * 178Er
 * style="text-align:right" | 68
 * style="text-align:right" | 110
 * 177.95678(64)#
 * 4# s (>300 ns)
 * β−
 * 178Tm
 * 0+
 * rowspan=2| 179Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 111
 * rowspan=2| 178.96127(54)#
 * rowspan=2| 3# s (>550 ns)
 * β−
 * 179Tm
 * rowspan=2| 3/2−#
 * rowspan=2|
 * rowspan=2|
 * β−, n
 * 178Tm
 * rowspan=2| 180Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 112
 * rowspan=2| 179.96438(54)#
 * rowspan=2| 2# s (>550 ns)
 * β−
 * 180Tm
 * rowspan=2| 0+
 * rowspan=2|
 * rowspan=2|
 * β−, n
 * 179Tm
 * 169Tm
 * 1/2−
 * style="text-indent:1em" | 169m1Er
 * colspan="3" style="text-indent:2em" | 92.05(10) keV
 * 285(20) ns
 * IT
 * 169Er
 * (5/2-)
 * style="text-indent:1em" | 169m2Er
 * colspan="3" style="text-indent:2em" | 243.69(17) keV
 * 200(10) ns
 * IT
 * 169Er
 * 7/2+
 * 170Er
 * style="text-align:right" | 68
 * style="text-align:right" | 102
 * 169.9354719(15)
 * colspan=3 align=center|Observationally Stable
 * 0+
 * 0.14910(36)
 * 171Er
 * style="text-align:right" | 68
 * style="text-align:right" | 103
 * 170.93803746(15)
 * 7.516(2) h
 * β−
 * 171Tm
 * 5/2−
 * style="text-indent:1em" | 171mEr
 * colspan="3" style="text-indent:2em" | 198.61(9) keV|
 * 210(10) ns
 * IT
 * 171Er
 * 1/2−
 * 172Er
 * style="text-align:right" | 68
 * style="text-align:right" | 104
 * 171.939363(4)
 * 49.3(5) h
 * β−
 * 172Tm
 * 0+
 * style="text-indent:1em" | 172mEr
 * colspan="3" style="text-indent:2em" | 1.5009(3) MeV
 * 579(62) ns
 * IT
 * 172Er
 * (6+)
 * 173Er
 * style="text-align:right" | 68
 * style="text-align:right" | 105
 * 172.94240(21)#
 * 1.434(17) min
 * β−
 * 173Tm
 * (7/2−)
 * 174Er
 * style="text-align:right" | 68
 * style="text-align:right" | 106
 * 173.94423(32)#
 * 3.2(2) min
 * β−
 * 174Tm
 * 0+
 * style="text-indent:1em" | 174mEr
 * colspan="3" style="text-indent:2em" | 1.1115(7) MeV
 * 3.9(3) s
 * IT
 * 174Er
 * 8-
 * 175Er
 * style="text-align:right" | 68
 * style="text-align:right" | 107
 * 174.94777(43)#
 * 1.2(3) min
 * β−
 * 175Tm
 * 9/2+#
 * 176Er
 * style="text-align:right" | 68
 * style="text-align:right" | 108
 * 175.94994(43)#
 * 12# s (>300 ns)
 * β−
 * 176Tm
 * 0+
 * 177Er
 * style="text-align:right" | 68
 * style="text-align:right" | 109
 * 176.95399(54)#
 * 8# s (>300 ns)
 * β−
 * 177Tm
 * 1/2−#
 * 178Er
 * style="text-align:right" | 68
 * style="text-align:right" | 110
 * 177.95678(64)#
 * 4# s (>300 ns)
 * β−
 * 178Tm
 * 0+
 * rowspan=2| 179Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 111
 * rowspan=2| 178.96127(54)#
 * rowspan=2| 3# s (>550 ns)
 * β−
 * 179Tm
 * rowspan=2| 3/2−#
 * rowspan=2|
 * rowspan=2|
 * β−, n
 * 178Tm
 * rowspan=2| 180Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 112
 * rowspan=2| 179.96438(54)#
 * rowspan=2| 2# s (>550 ns)
 * β−
 * 180Tm
 * rowspan=2| 0+
 * rowspan=2|
 * rowspan=2|
 * β−, n
 * 179Tm
 * style="text-align:right" | 68
 * style="text-align:right" | 109
 * 176.95399(54)#
 * 8# s (>300 ns)
 * β−
 * 177Tm
 * 1/2−#
 * 178Er
 * style="text-align:right" | 68
 * style="text-align:right" | 110
 * 177.95678(64)#
 * 4# s (>300 ns)
 * β−
 * 178Tm
 * 0+
 * rowspan=2| 179Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 111
 * rowspan=2| 178.96127(54)#
 * rowspan=2| 3# s (>550 ns)
 * β−
 * 179Tm
 * rowspan=2| 3/2−#
 * rowspan=2|
 * rowspan=2|
 * β−, n
 * 178Tm
 * rowspan=2| 180Er
 * rowspan=2 style="text-align:right" | 68
 * rowspan=2 style="text-align:right" | 112
 * rowspan=2| 179.96438(54)#
 * rowspan=2| 2# s (>550 ns)
 * β−
 * 180Tm
 * rowspan=2| 0+
 * rowspan=2|
 * rowspan=2|
 * β−, n
 * 179Tm
 * rowspan=2| 2# s (>550 ns)
 * β−
 * 180Tm
 * rowspan=2| 0+
 * rowspan=2|
 * rowspan=2|
 * β−, n
 * 179Tm
 * 179Tm