Isotopes of terbium

Naturally occurring terbium (₆₅Tb) is composed of one stable isotope, ¹⁵⁹Tb. Thirty-seven radioisotopes have been characterized, with the most stable being ¹⁵⁸Tb with a half-life of 180 years, ¹⁵⁷Tb with a half-life of 71 years, and ¹⁶⁰Tb with a half-life of 72.3 days. All of the remaining radioactive isotopes have half-lives that are less than one week, and the majority of these have half-lives that are less than 24 seconds. This element also has 27 meta states, with the most stable being ^156m2Tb (t_1/2 = 24.4 hours), ^154m2Tb (t_1/2 = 22.7 hours) and ^154m1Tb (t_1/2 = 21.5 hours).

The primary decay mode before the most abundant stable isotope, ¹⁵⁹Tb, is electron capture to gadolinium isotopes, and the primary mode after is beta decay to dysprosium isotopes.

List of isotopes

|-id=Terbium-135 | ¹³⁵Tb | style="text-align:right" | 65 | style="text-align:right" | 70 | 134.96452(43)# | 1.01(28)&nbsp;ms | p | ¹³⁴Gd | (7/2−) | |-id=Terbium-136 | ¹³⁶Tb | style="text-align:right" | 65 | style="text-align:right" | 71 | 135.96146(54)# | 200#&nbsp;ms<br>[>310&nbsp;ns] | | | 5−# | |-id=Terbium-137 | ¹³⁷Tb | style="text-align:right" | 65 | style="text-align:right" | 72 | 136.95602(43)# | 600#&nbsp;ms<br>[>310&nbsp;ns] | | | 3/2+# | |-id=Terbium-138 | ¹³⁸Tb | style="text-align:right" | 65 | style="text-align:right" | 73 | 137.95319(32)# | 800#&nbsp;ms<br>[>310&nbsp;ns] | | | 2+# | |-id=Terbium-139 | ¹³⁹Tb | style="text-align:right" | 65 | style="text-align:right" | 74 | 138.94833(32)# | 1.6(2)&nbsp;s | β⁺ | ¹³⁹Gd | 5/2−# | |-id=Terbium-140 | rowspan=3|¹⁴⁰Tb | rowspan=3 style="text-align:right" | 65 | rowspan=3 style="text-align:right" | 75 | rowspan=3|139.94581(86) | rowspan=3|2.29(15)&nbsp;s | β⁺ (99.74%) | ¹⁴⁰Gd | rowspan=3|(7+) | rowspan=3| |- | EC (<3%) | ¹⁴⁰Gd |- | β⁺, p (0.26%) | ¹³⁹Eu |-id=Terbium-141 | ¹⁴¹Tb | style="text-align:right" | 65 | style="text-align:right" | 76 | 140.94145(11) | 3.5(2)&nbsp;s | β⁺ | ¹⁴¹Gd | (5/2−) | |-id=Terbium-141m | style="text-indent:1em" | ^141mTb | colspan="3" style="text-indent:2em" | 0(200)#&nbsp;keV | 7.9(6)&nbsp;s | β⁺ | ¹⁴¹Gd | 11/2−# | |-id=Terbium-142 | rowspan=3|¹⁴²Tb | rowspan=3 style="text-align:right" | 65 | rowspan=3 style="text-align:right" | 77 | rowspan=3|141.93928(75) | rowspan=3|597(17)&nbsp;ms | β⁺ (96.8%) | ¹⁴²Gd | rowspan=3|1+ | rowspan=3| |- | EC (3.2%) | ¹⁴²Gd |- | β⁺, p (0.0022%) | ¹⁴¹Eu |-id=Terbium-142m1 | style="text-indent:1em" | ^142m1Tb | colspan="3" style="text-indent:2em" | 279.7(4)&nbsp;keV | 303(17)&nbsp;ms | IT | ¹⁴²Tb | 5− | |-id=Terbium-142m2 | style="text-indent:1em" | ^142m2Tb | colspan="3" style="text-indent:2em" | 652.1(6)&nbsp;keV | 26(1)&nbsp;μs | IT | ¹⁴²Tb | 8+ | |-id=Terbium-143 | ¹⁴³Tb | style="text-align:right" | 65 | style="text-align:right" | 78 | 142.935137(55) | 12(1)&nbsp;s | β⁺ | ¹⁴³Gd | (11/2−) | |-id=Terbium-143m | style="text-indent:1em" | ^143mTb | colspan="3" style="text-indent:2em" | 0(100)#&nbsp;keV | 17(4)&nbsp;s | | | 5/2+# | |-id=Terbium-144 | ¹⁴⁴Tb | style="text-align:right" | 65 | style="text-align:right" | 79 | 143.933045(30) | ~1&nbsp;s | β⁺ | ¹⁴⁴Gd | 1+ | |-id=Terbium-144m1 | rowspan=2 style="text-indent:1em" | ^144m1Tb | rowspan=2 colspan="3" style="text-indent:2em" | 396.9(5)&nbsp;keV | rowspan=2|4.25(15)&nbsp;s | IT (66%) | ¹⁴⁴Tb | rowspan=2|6− | rowspan=2| |- | β⁺ (34%) | ¹⁴⁴Gd |-id=Terbium-144m2 | style="text-indent:1em" | ^144m2Tb | colspan="3" style="text-indent:2em" | 476.2(5)&nbsp;keV | 2.8(3)&nbsp;μs | IT | ¹⁴⁴Tb | (8−) | |-id=Terbium-144m3 | style="text-indent:1em" | ^144m3Tb | colspan="3" style="text-indent:2em" | 517.1(5)&nbsp;keV | 670(60)&nbsp;ns | IT | ¹⁴⁴Tb | (9+) | |-id=Terbium-144m4 | style="text-indent:1em" | ^144m4Tb | colspan="3" style="text-indent:2em" | 544.5(6)&nbsp;keV | <300&nbsp;ns | IT | ¹⁴⁴Tb | (10+) | |-id=Terbium-145 | ¹⁴⁵Tb | style="text-align:right" | 65 | style="text-align:right" | 80 | 144.92872(12) | 30.9(6)&nbsp;s | β⁺ | ¹⁴⁵Gd | (11/2−) | |-id=Terbium-145m | style="text-indent:1em" | ^145mTb | colspan="3" style="text-indent:2em" | 860(230)&nbsp;keV | | | | (3/2+) | |-id=Terbium-146 | ¹⁴⁶Tb | style="text-align:right" | 65 | style="text-align:right" | 81 | 145.927253(48) | 8(4)&nbsp;s | β⁺ | ¹⁴⁶Gd | 1+ | |-id=Terbium-146m1 | style="text-indent:1em" | ^146m1Tb | colspan="3" style="text-indent:2em" | 150(100)#&nbsp;keV | 24.1(5)&nbsp;s | β⁺ | ¹⁴⁶Gd | 5− | |-id=Terbium-146m2 | style="text-indent:1em" | ^146m2Tb | colspan="3" style="text-indent:2em" | 930(100)#&nbsp;keV | 1.18(2)&nbsp;ms | IT | ¹⁴⁶Tb | 10+ | |-id=Terbium-147 | ¹⁴⁷Tb | style="text-align:right" | 65 | style="text-align:right" | 82 | 146.9240546(87) | 1.64(3)&nbsp;h | β⁺ | ¹⁴⁷Gd | (1/2+) | |-id=Terbium-147m | style="text-indent:1em" | ^147mTb | colspan="3" style="text-indent:2em" | 50.6(9)&nbsp;keV | 1.87(5)&nbsp;min | β⁺ | ¹⁴⁷Gd | (11/2−) | |-id=Terbium-148 | ¹⁴⁸Tb | style="text-align:right" | 65 | style="text-align:right" | 83 | 147.924275(13) | 60(1)&nbsp;min | β⁺ | ¹⁴⁸Gd | 2− | |-id=Terbium-148m1 | style="text-indent:1em" | ^148m1Tb | colspan="3" style="text-indent:2em" | 90.1(3)&nbsp;keV | 2.20(5)&nbsp;min | β⁺ | ¹⁴⁸Gd | (9)+ | |-id=Terbium-148m2 | style="text-indent:1em" | ^148m2Tb | colspan="3" style="text-indent:2em" | 8618.6(10)&nbsp;keV | 1.310(7)&nbsp;μs | IT | ¹⁴⁸Tb | (27+) | |-id=Terbium-149 | rowspan=2|¹⁴⁹Tb | rowspan=2 style="text-align:right" | 65 | rowspan=2 style="text-align:right" | 84 | rowspan=2|148.9232538(39) | rowspan=2|4.118(25)&nbsp;h | β⁺ (83.3%) | ¹⁴⁹Gd | rowspan=2|1/2+ | rowspan=2| |- | α (16.7%) | ¹⁴⁵Eu |-id=Terbium-149m | rowspan=2 style="text-indent:1em" | ^149mTb | rowspan=2 colspan="3" style="text-indent:2em" | 35.78(13)&nbsp;keV | rowspan=2|4.16(4)&nbsp;min | β⁺ (99.98%) | ¹⁴⁹Gd | rowspan=2|11/2− | rowspan=2| |- | α (0.022%) | ¹⁴⁵Eu |-id=Terbium-150 | ¹⁵⁰Tb | style="text-align:right" | 65 | style="text-align:right" | 85 | 149.9236648(79) | 3.48(16)&nbsp;h | β⁺ | ¹⁵⁰Gd | (2)− | |-id=Terbium-150m | style="text-indent:1em" | ^150mTb | colspan="3" style="text-indent:2em" | 461(27)&nbsp;keV | 5.8(2)&nbsp;min | β⁺ | ¹⁵⁰Gd | 9+ | |-id=Terbium-151 | rowspan=2|¹⁵¹Tb | rowspan=2 style="text-align:right" | 65 | rowspan=2 style="text-align:right" | 86 | rowspan=2|150.9231090(44) | rowspan=2|17.609(1)&nbsp;h | β⁺ (99.99%) | ¹⁵¹Gd | rowspan=2|1/2+ | rowspan=2| |- | α (0.0095%) | ¹⁴⁷Eu |-id=Terbium-151m | rowspan=2 style="text-indent:1em" | ^151mTb | rowspan=2 colspan="3" style="text-indent:2em" | 99.53(5)&nbsp;keV | rowspan=2|25(3)&nbsp;s | IT (93.4%) | ¹⁵¹Tb | rowspan=2|11/2− | rowspan=2| |- | β⁺ (6.6%) | ¹⁵¹Gd |-id=Terbium-152 | rowspan=3|¹⁵²Tb | rowspan=3 style="text-align:right" | 65 | rowspan=3 style="text-align:right" | 87 | rowspan=3|151.924082(43) | rowspan=3|17.8784(95)&nbsp;h | EC (83%) | rowspan=2|¹⁵²Gd | rowspan=3|2− | rowspan=3| |- | β⁺ (17%) |- | α (<7×10^{−7}%) | ¹⁴⁸Eu |-id=Terbium-152m1 | style="text-indent:1em" | ^152m1Tb | colspan="3" style="text-indent:2em" | 342.15(16)&nbsp;keV | 960(10)&nbsp;ns | IT | ¹⁵²Tb | 5− | |-id=Terbium-152m2 | rowspan=2 style="text-indent:1em" | ^152m2Tb | rowspan=2 colspan="3" style="text-indent:2em" | 501.74(19)&nbsp;keV | rowspan=2|4.2(1)&nbsp;min | IT (78.9%) | ¹⁵²Tb | rowspan=2|8+ | rowspan=2| |- | β⁺ (21.1%) | ¹⁵²Gd |-id=Terbium-153 | ¹⁵³Tb | style="text-align:right" | 65 | style="text-align:right" | 88 | 152.9234417(42) | 2.34(1)&nbsp;d | β⁺ | ¹⁵³Gd | 5/2+ | |-id=Terbium-153m | style="text-indent:1em" | ^153mTb | colspan="3" style="text-indent:2em" | 163.175(5)&nbsp;keV | 186(4)&nbsp;μs | IT | ¹⁵³Tb | 11/2− | |-id=Terbium-154 | ¹⁵⁴Tb | style="text-align:right" | 65 | style="text-align:right" | 89 | 153.924684(49) | 9.994(39)&nbsp;h | β⁺ | ¹⁵⁴Gd | 3− | |-id=Terbium-154m1 | style="text-indent:1em" | ^154m1Tb | colspan="3" style="text-indent:2em" | 130(50)#&nbsp;keV | 21.5(4)&nbsp;h | β⁺ | ¹⁵⁴Gd | 0− | |-id=Terbium-154m2 | style="text-indent:1em" | ^154m2Tb | colspan="3" style="text-indent:2em" | 200(150)#&nbsp;keV | 22.7(5)&nbsp;h | β⁺ | ¹⁵⁴Gd | 7− | |-id=Terbium-154m3 | style="text-indent:1em" | ^154m3Tb | colspan="3" style="text-indent:2em" | 405(150)#&nbsp;keV | 513(42)&nbsp;ns | IT | ¹⁵⁴Tb | | |-id=Terbium-155 | ¹⁵⁵Tb | style="text-align:right" | 65 | style="text-align:right" | 90 | 154.923510(11) | 5.2346(36)&nbsp;d | EC | ¹⁵⁵Gd | 3/2+ | |-id=Terbium-156 | ¹⁵⁶Tb | style="text-align:right" | 65 | style="text-align:right" | 91 | 155.9247542(40) | 5.35(10)&nbsp;d | β⁺ | ¹⁵⁶Gd | 3− | |-id=Terbium-156m1 | style="text-indent:1em" | ^156m1Tb | colspan="3" style="text-indent:2em" | 88.4(2)&nbsp;keV | 5.3(2)&nbsp;h | IT | ¹⁵⁶Tb | (0+) | |-id=Terbium-156m2 | style="text-indent:1em" | ^156m2Tb | colspan="3" style="text-indent:2em" | 100(50)#&nbsp;keV | 24.4(10)&nbsp;h | IT | ¹⁵⁶Tb | (7−) | |-id=Terbium-157 | ¹⁵⁷Tb | style="text-align:right" | 65 | style="text-align:right" | 92 | 156.9240319(11) | 71(7)&nbsp;y | EC | ¹⁵⁷Gd | 3/2+ | |-id=Terbium-158 | rowspan=2|¹⁵⁸Tb | rowspan=2 style="text-align:right" | 65 | rowspan=2 style="text-align:right" | 93 | rowspan=2|157.9254199(14) | rowspan=2|180(11)&nbsp;y | β⁺ (83.4%) | ¹⁵⁸Gd | rowspan=2|3− | rowspan=2| |- | β^− (16.6%) | ¹⁵⁸Dy |-id=Terbium-158m1 | style="text-indent:1em" | ^158m1Tb | colspan="3" style="text-indent:2em" | 110.3(12)&nbsp;keV | 10.70(17)&nbsp;s | IT | ¹⁵⁸Tb | 0− | |-id=Terbium-158m2 | style="text-indent:1em" | ^158m2Tb | colspan="3" style="text-indent:2em" | 388.39(11)&nbsp;keV | 0.40(4)&nbsp;ms | IT | ¹⁵⁸Tb | 7− | |-id=Terbium-159 | ¹⁵⁹Tb | style="text-align:right" | 65 | style="text-align:right" | 94 | 158.9253537(12) | colspan=3 align=center|Stable | 3/2+ | 1.0000 |-id=Terbium-160 | ¹⁶⁰Tb | style="text-align:right" | 65 | style="text-align:right" | 95 | 159.9271746(12) | 72.3(2)&nbsp;d | β^− | ¹⁶⁰Dy | 3− | |-id=Terbium-161 | ¹⁶¹Tb | style="text-align:right" | 65 | style="text-align:right" | 96 | 160.9275768(13) | 6.948(5)&nbsp;d | β^− | ¹⁶¹Dy | 3/2+ | |-id=Terbium-162 | ¹⁶²Tb | style="text-align:right" | 65 | style="text-align:right" | 97 | 161.9292754(22) | 7.60(15)&nbsp;min | β^− | ¹⁶²Dy | (1−) | |-id=Terbium-162m | style="text-indent:1em" | ^162mTb | colspan="3" style="text-indent:2em" | 286(3)&nbsp;keV | 10#&nbsp;min | | | 4−# | |-id=Terbium-163 | ¹⁶³Tb | style="text-align:right" | 65 | style="text-align:right" | 98 | 162.9306536(44) | 19.5(3)&nbsp;min | β^− | ¹⁶³Dy | 3/2+ | |-id=Terbium-164 | ¹⁶⁴Tb | style="text-align:right" | 65 | style="text-align:right" | 99 | 163.9333276(20) | 3.0(1)&nbsp;min | β^− | ¹⁶⁴Dy | (5+) | |-id=Terbium-164m | style="text-indent:1em" | ^164mTb | colspan="3" style="text-indent:2em" | 145(12)&nbsp;keV | 2#&nbsp;min | | | 2+# | |-id=Terbium-165 | ¹⁶⁵Tb | style="text-align:right" | 65 | style="text-align:right" | 100 | 164.9349552(17) | 2.11(10)&nbsp;min | β^− | ¹⁶⁵Dy | (3/2+) | |-id=Terbium-165m | style="text-indent:1em" | ^165mTb | colspan="3" style="text-indent:2em" | 207(5)&nbsp;keV | 0.81(8)&nbsp;μs | IT | ¹⁶⁵Tb | (7/2−) | |-id=Terbium-166 | ¹⁶⁶Tb | style="text-align:right" | 65 | style="text-align:right" | 101 | 165.9379397(16) | 27.1(15)&nbsp;s | β^− | ¹⁶⁶Dy | (1−) | |-id=Terbium-166m | style="text-indent:1em" | ^166mTb | colspan="3" style="text-indent:2em" | 159.0(15)&nbsp;keV | 3.5(4)&nbsp;μs | IT | ¹⁶⁶Tb | 4−# | |-id=Terbium-167 | ¹⁶⁷Tb | style="text-align:right" | 65 | style="text-align:right" | 102 | 166.9400070(21) | 18.9(16)&nbsp;s | β^− | ¹⁶⁷Dy | (3/2+) | |-id=Terbium-167m | style="text-indent:1em" | ^167mTb | colspan="3" style="text-indent:2em" | 200(6)&nbsp;keV | 1.2(1)&nbsp;μs | IT | ¹⁶⁷Tb | (7/2−) | |-id=Terbium-168 | ¹⁶⁸Tb | style="text-align:right" | 65 | style="text-align:right" | 103 | 167.9433371(45) | 9.4(4)&nbsp;s | β^− | ¹⁶⁸Dy | (4−) | |-id=Terbium-168m | style="text-indent:1em" | ^168mTb | colspan="3" style="text-indent:2em" | 211(1)&nbsp;keV | 0.71(3)&nbsp;μs | IT | ¹⁶⁸Tb | (6+) | |-id=Terbium-169 | ¹⁶⁹Tb | style="text-align:right" | 65 | style="text-align:right" | 104 | 168.94581(32)# | 5.13(32)&nbsp;s | β^− | ¹⁶⁹Dy | 3/2+# | |-id=Terbium-170 | ¹⁷⁰Tb | style="text-align:right" | 65 | style="text-align:right" | 105 | 169.94986(32)# | 960(78)&nbsp;ms | β^− | ¹⁷⁰Dy | 2−# | |-id=Terbium-171 | ¹⁷¹Tb | style="text-align:right" | 65 | style="text-align:right" | 106 | 170.95301(43)# | 1.23(10)&nbsp;s | β^− | ¹⁷¹Dy | 3/2+# | |-id=Terbium-172 | ¹⁷²Tb | style="text-align:right" | 65 | style="text-align:right" | 107 | 171.95739(54)# | 760(190)&nbsp;ms | β^− | ¹⁷²Dy | 6+# | |-id=Terbium-173 | ¹⁷³Tb | style="text-align:right" | 65 | style="text-align:right" | 108 | 172.96081(54)# | 400#&nbsp;ms<br>[>550&nbsp;ns] | | | 3/2+# | |-id=Terbium-174 | ¹⁷⁴Tb | style="text-align:right" | 65 | style="text-align:right" | 109 | 173.96568(54)# | 240#&nbsp;ms<br>[>550&nbsp;ns] | | | 2−# | |-id=Terbium-175 | ¹⁷⁵Tb | style="text-align:right" | 65 | style="text-align:right" | 110 | | | | | |

See also

Daughter products other than terbium

• Isotopes of dysprosium
• Isotopes of gadolinium
• Isotopes of europium

References