Notation. Nuclides are written with the mass number as a left superscript (e.g., ¹⁶⁵Dy).
Columns. Stable? refers to the ground state; a few notable isomers follow afterward. Half‑life and Decay mode(s) are evaluated values; Daughter is the immediate product. Radiation summarizes emissions (β⁺/β⁻/α; X/γ from EC/IT; “p” = β‑delayed proton). Origin sketches a typical production path. Uses flags M (medical), I (industrial), R (research).
Data spine. Ground‑state half‑lives, branches and daughters come from the consolidated Isotopes of dysprosium table (NUBASE/ENSDF/AME based). Natural isotopic composition is from CIAAW. Medical use of ¹⁶⁵Dy is documented in nuclear‑medicine literature. Capture cross‑section context is from evaluated Dy‑isotope datasets. (Wikipedia, CIAAW, tech.snmjournals.org, ScienceDirect)
Dysprosium — ground states (key isomers follow)
| Isotope | Z | A | Stable? | Half‑life | Decay mode(s) (main) | Daughter | Radiation | Origin | Typical uses / notes |
|---|---|---|---|---|---|---|---|---|---|
| ¹³⁹Dy | 66 | 139 | No | ~0.6 s | β⁺ (~89%); β⁺p (~11%) | ¹³⁹Tb; ¹³⁸Gd | β⁺; p | Synthetic (p‑rich) | R. (Wikipedia) |
| ¹⁴⁰Dy | 66 | 140 | No | ~0.7 s (#) | β⁺ (±p?) | ¹⁴⁰Tb (± ¹³⁹Gd) | β⁺ (p) | Synthetic (p‑rich) | R. (Wikipedia) |
| ¹⁴¹Dy | 66 | 141 | No | 0.90 s | β⁺ (±p?) | ¹⁴¹Tb (± ¹⁴⁰Gd) | β⁺ (p) | Synthetic | R. (Wikipedia) |
| ¹⁴²Dy | 66 | 142 | No | 2.3 s | β⁺ (90%); EC (10%); β⁺p (0.06%) | ¹⁴²Tb; ¹⁴¹Gd | β⁺; X/γ (EC); p | Synthetic | R. (Wikipedia) |
| ¹⁴³Dy | 66 | 143 | No | 5.6 s | β⁺ (±p?) | ¹⁴³Tb (± ¹⁴²Gd) | β⁺ (p) | Synthetic | R. (Wikipedia) |
| ¹⁴⁴Dy | 66 | 144 | No | 9.1 s | β⁺ (±p?) | ¹⁴⁴Tb (± ¹⁴³Gd) | β⁺ (p) | Synthetic | R. (Wikipedia) |
| ¹⁴⁵Dy | 66 | 145 | No | 9.5 s | β⁺ (±p?) | ¹⁴⁵Tb (± ¹⁴⁴Gd) | β⁺ (p) | Synthetic | R. (Wikipedia) |
| ¹⁴⁶Dy | 66 | 146 | No | 33.2 s | β⁺ | ¹⁴⁶Tb | β⁺ | Activation/Synth. | R. (Wikipedia) |
| ¹⁴⁷Dy | 66 | 147 | No | 67 s | β⁺ (99.95%); β⁺p (0.05%) | ¹⁴⁷Tb; ¹⁴⁶Gd | β⁺; p | Activation/Synth. | R. (Wikipedia) |
| ¹⁴⁸Dy | 66 | 148 | No | 3.3 min | β⁺ | ¹⁴⁸Tb | β⁺ | Activation/Synth. | R. (Wikipedia) |
| ¹⁴⁹Dy | 66 | 149 | No | 4.20 min | β⁺ | ¹⁴⁹Tb | β⁺ | Activation/Synth. | R. (Wikipedia) |
| ¹⁵⁰Dy | 66 | 150 | No | 7.17 min | β⁺ (66.4%); α (33.6%) | ¹⁵⁰Tb; ¹⁴⁶Gd | β⁺; α | Activation/Synth. | R; rare sizable α branch. (Wikipedia) |
| ¹⁵¹Dy | 66 | 151 | No | 17.9 min | β⁺ (94.4%); α (5.6%) | ¹⁵¹Tb; ¹⁴⁷Gd | β⁺; α | Activation/Synth. | R. (Wikipedia) |
| ¹⁵²Dy | 66 | 152 | No | 2.38 h | EC (99.90%); α (0.10%) | ¹⁵²Tb; ¹⁴⁸Gd | X/γ (EC); α | Activation | R; parent of ¹⁵²Tb (PET). (Wikipedia) |
| ¹⁵³Dy | 66 | 153 | No | 6.4 h | β⁺ (≈100%); α (0.009%) | ¹⁵³Tb; ¹⁴⁹Gd | β⁺; α | Activation | R. (Wikipedia) |
| ¹⁵⁴Dy | 66 | 154 | No | 1.40(8)×10⁶ y | α | ¹⁵⁰Gd | α | Primordial (extinct in practice) | Early‑Solar‑System chronometer work. (Wikipedia) |
| ¹⁵⁵Dy | 66 | 155 | No | 9.9 h | β⁺ | ¹⁵⁵Tb | β⁺ | Activation | R. (Wikipedia) |
| ¹⁵⁶Dy | 66 | 156 | Obs.-stable | — | (rare α/ββ predicted) | — | — | Natural | Minor natural isotope. (CIAAW) |
| ¹⁵⁷Dy | 66 | 157 | No | 8.14 h | β⁺ | ¹⁵⁷Tb | β⁺ | Activation | R. (Wikipedia) |
| ¹⁵⁸Dy | 66 | 158 | Obs.-stable | — | — | — | — | Natural | Minor natural isotope. (CIAAW) |
| ¹⁵⁹Dy | 66 | 159 | No | 144.4 d | EC | ¹⁵⁹Tb | X/γ (EC) | Activation | Long‑lived tracer; γ standard sets. (Wikipedia) |
| ¹⁶⁰Dy | 66 | 160 | Obs.-stable | — | — | — | — | Natural | Natural Dy. (CIAAW) |
| ¹⁶¹Dy | 66 | 161 | Obs.-stable | — | — | — | — | Natural | NMR‑active (I=5/2). (Wikipedia) |
| ¹⁶²Dy | 66 | 162 | Obs.-stable | — | — | — | — | Natural | Natural Dy. (CIAAW) |
| ¹⁶³Dy | 66 | 163 | Stable | — | — | — | — | Natural | Heaviest “theoretically stable” nuclide; fully‑ionized ¹⁶³Dy can bound‑state β⁻ → ¹⁶³Ho (T½≈47 d). (Wikipedia) |
| ¹⁶⁴Dy | 66 | 164 | Stable | — | — | — | — | Natural (most abundant) | High thermal n‑absorption. (Wikipedia, ScienceDirect) |
| ¹⁶⁵Dy | 66 | 165 | No | 2.332 h | β⁻ | ¹⁶⁵Ho | β⁻; γ (weak) | Activation: ¹⁶⁴Dy(n,γ) | M: radiation synovectomy (¹⁶⁵Dy‑HMA/FHMA). (Wikipedia, tech.snmjournals.org, PubMed) |
| ¹⁶⁶Dy | 66 | 166 | No | 81.6 h | β⁻ | ¹⁶⁶Ho | β⁻ | Activation | R (decay‑data, cross‑section studies). (Wikipedia) |
| ¹⁶⁷Dy | 66 | 167 | No | 6.20 min | β⁻ | ¹⁶⁷Ho | β⁻ | Neutron‑rich FP / activation | R. (Wikipedia) |
| ¹⁶⁸Dy | 66 | 168 | No | 8.7 min | β⁻ | ¹⁶⁸Ho | β⁻ | Neutron‑rich FP | R. (Wikipedia) |
| ¹⁶⁹Dy | 66 | 169 | No | 39 s | β⁻ | ¹⁶⁹Ho | β⁻ | Neutron‑rich FP | R. (Wikipedia) |
| ¹⁷⁰Dy | 66 | 170 | No | 54.9 s | β⁻ | ¹⁷⁰Ho | β⁻ | In‑flight fission | R. (Wikipedia) |
| ¹⁷¹Dy | 66 | 171 | No | 4.07 s | β⁻ | ¹⁷¹Ho | β⁻ | In‑flight fission | R. (Wikipedia) |
| ¹⁷²Dy | 66 | 172 | No | 3.4 s | β⁻ | ¹⁷²Ho | β⁻ | In‑flight fission | R. (Wikipedia) |
| ¹⁷³Dy | 66 | 173 | No | 1.43 s | β⁻ (± β−,n?) | ¹⁷³Ho (± ¹⁷²Ho) | β⁻; n | In‑flight fission | R. (Wikipedia) |
| ¹⁷⁴Dy | 66 | 174 | No | ~1 s | β⁻? (± β−,n?) | ¹⁷⁴Ho (± ¹⁷³Ho) | β⁻; n | In‑flight fission | R. (Wikipedia) |
| ¹⁷⁵Dy | 66 | 175 | No | ~0.39 s | β⁻? (± β−,n?) | ¹⁷⁵Ho (± ¹⁷⁴Ho) | β⁻; n | In‑flight fission | R. (Wikipedia) |
| ¹⁷⁶Dy | 66 | 176 | No | ~0.44 s | β⁻? (± β−,n?) | ¹⁷⁶Ho (± ¹⁷⁵Ho) | β⁻; n | In‑flight fission | R. (Wikipedia) |
Primary table source: evaluated dysprosium isotope list with half‑lives/branches/daughters. Values marked # indicate trend‑assisted evaluations where direct measurements are sparse. (Wikipedia)
Selected isomers (applied/diagnostic interest)
- ¹⁶⁵ᵐDy — 1.257 min, IT (97.8%) → ¹⁶⁵Dy / β⁻ (2.2%) → ¹⁶⁵Ho; appears with medical ¹⁶⁵Dy preparations. (Wikipedia)
- ¹⁴⁷ᵐDy — 55.2 s, mixed β⁺/IT; long‑lived p‑rich isomer used in level‑scheme timing. (Wikipedia)
- ¹⁷²ᵐDy — 710 ms, IT (81%) → ¹⁷²Dy / β⁻ (19%) → ¹⁷²Ho; high‑spin doorway at the n‑rich edge. (Wikipedia)
- ¹⁷⁰ᵐDy — 0.99 µs, prompt IT; fast‑timing calibrant in heavy‑ion work. (Wikipedia)
Natural isotopic composition (terrestrial Dy — CIAAW)
Amount fractions: ¹⁵⁶Dy 0.00056(3), ¹⁵⁸Dy 0.00095(3), ¹⁶⁰Dy 0.02329(18), ¹⁶¹Dy 0.18889(42), ¹⁶²Dy 0.25475(36), ¹⁶³Dy 0.24896(42), ¹⁶⁴Dy 0.28260(54).
Standard atomic weight: Aᵣ(Dy) = 162.500(1). (Dy is unusual in that ¹⁶³Dy and ¹⁶⁴Dy are considered theoretically stable, not just observationally stable.) (CIAAW, Wikipedia)
Applied & research highlights (Dy)
- Intra‑articular therapy (synovectomy). ¹⁶⁵Dy (2.332 h, β⁻), prepared as Dy hydroxide or ferric‑hydroxide macroaggregates (HMA/FHMA), has been used for radiation synovectomy of the knee; its short half‑life reduces leakage risk compared with older ⁹⁰Y or ¹⁹⁸Au colloids. Production is straightforward via ¹⁶⁴Dy(n,γ)¹⁶⁵Dy. (Wikipedia, tech.snmjournals.org, PubMed)
- Neutron capture and control materials. Natural Dy (especially ¹⁶⁴Dy) has a large thermal capture cross‑section (order ~2.6 kb), supporting its use (often alloyed) in control rods and neutron‑absorbing components; evaluated cross‑section sets cover ¹⁵⁶, ¹⁵⁸, ¹⁶⁰–¹⁶⁴Dy. (ScienceDirect, ResearchGate)
- Rare‑decay physics. ¹⁶³Dy can undergo bound‑state β⁻ decay only when fully ionized (storage‑ring conditions), a textbook example of environment‑enabled decay. (Wikipedia)
Totals — Dysprosium (Z = 66)
- Ground‑state isotopes listed: 38 (A = 139–176; edge entries include evaluated # values).
- Stable (ground states): 7 (¹⁵⁶, ¹⁵⁸, ¹⁶⁰, ¹⁶¹, ¹⁶², ¹⁶³, ¹⁶⁴; the first four of these are “observationally stable”).
- Unstable (ground states): 31 (includes long‑lived ¹⁵⁴Dy and ¹⁵⁹Dy).
(Counts reflect the current evaluated table.) (Wikipedia)
Running cumulative totals (through Dy): add +38 total / +7 stable / +31 unstable to your ledger (after Gd: ≥1952 total, 191 stable, ≥1761 unstable) → ≥1990 total, 198 stable, ≥1792 unstable.
Sources (load‑bearing)
- Comprehensive isotope list & decay data (table above): Isotopes of dysprosium (NUBASE/ENSDF/AME compiled; updated 2025). (Wikipedia)
- Natural isotopic composition (fractions & remarks): CIAAW — Atomic Weight of Dysprosium. (CIAAW)
- ¹⁶⁵Dy medical use / synovectomy: J. Nucl. Med. Tech. review on Dy‑165 FHMA; PubMed report on Dy‑HMA formulation. (tech.snmjournals.org, PubMed)
- Neutron‑capture context: Evaluations of Dy‑isotope thermal capture (e.g., ¹⁶⁴Dy ≈ 2.6 kb). (ScienceDirect, ResearchGate)
Next element: Holmium — Ho (Z = 67).