Isotopes of dysprosium

Naturally occurring dysprosium (₆₆Dy) is composed of 7 stable isotopes, ¹⁵⁶Dy, ¹⁵⁸Dy, ¹⁶⁰Dy, ¹⁶¹Dy, ¹⁶²Dy, ¹⁶³Dy and ¹⁶⁴Dy, with ¹⁶⁴Dy being the most abundant (28.18% natural abundance). Twenty-nine radioisotopes have been characterized, with the most stable being ¹⁵⁴Dy with a half-life of 3.0 million years, ¹⁵⁹Dy with a half-life of 144.4 days, and ¹⁶⁶Dy with a half-life of 81.6 hours. All of the remaining radioactive isotopes have half-lives that are less than 10 hours, and the majority of these have half-lives that are less than 30 seconds. This element also has 12 meta states, with the most stable being ^165mDy (half-life 1.257 minutes), ^147mDy (half-life 55.7 seconds) and ^145mDy (half-life 13.6 seconds).

Main isotopes of dysprosium (₆₆Dy)

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct ^154Dy syn 3.0×10^6 y α ^150Gd ^156Dy 0.056% stable ^158Dy 0.095% stable ^160Dy 2.329% stable ^161Dy 18.889% stable ^162Dy 25.475% stable ^163Dy 24.896% stable ^164Dy 28.260% stable
Standard atomic weight Ar, standard(Dy)	162.500(1)[1]

The primary decay mode before the most abundant stable isotope, ¹⁶⁴Dy, is electron capture, and the primary mode after is beta decay. The primary decay products before ¹⁶⁴Dy are terbium isotopes, and the primary products after are holmium isotopes.

¹⁶⁴Dy is the heaviest theoretically stable nuclide, all heavier beta-stable nuclides are theorized to undergo alpha decay.

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life [n 4]	Decay mode [n 5]	Daughter isotope [n 6]	Spin and parity [n 7][n 4]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
^138Dy	66	72	137.96249(64)#	200# ms			0+
^139Dy	66	73	138.95954(54)#	600(200) ms			7/2+#
^140Dy	66	74	139.95401(54)#	700# ms	β^+	^140Tb	0+
^140mDy	2166.1(5) keV			7.0(5) μs			(8−)
^141Dy	66	75	140.95135(32)#	0.9(2) s	β^+	^141Tb	(9/2−)
					β^+, p (rare)	^140Gd
^142Dy	66	76	141.94637(39)#	2.3(3) s	β^+ (99.94%)	^142Tb	0+
					β^+, p (.06%)	^141Gd
^143Dy	66	77	142.94383(21)#	5.6(10) s	β^+	^143Tb	(1/2+)
					β^+, p (rare)	^142Gd
^143mDy	310.7(6) keV			3.0(3) s			(11/2−)
^144Dy	66	78	143.93925(3)	9.1(4) s	β^+	^144Tb	0+
					β^+, p (rare)	^143Gd
^145Dy	66	79	144.93743(5)	9.5(10) s	β^+	^145Tb	(1/2+)
					β^+, p (rare)	^144Gd
^145mDy	118.2(2) keV			14.1(7) s	β^+	^145Tb	(11/2−)
^146Dy	66	80	145.932845(29)	33.2(7) s	β^+	^146Tb	0+
^146mDy	2935.7(6) keV			150(20) ms	IT	^146Dy	(10+)#
^147Dy	66	81	146.931092(21)	40(10) s	β^+ (99.95%)	^147Tb	1/2+
					β^+, p (.05%)	^146Tb
^147m1Dy	750.5(4) keV			55(1) s	β^+ (65%)	^147Tb	11/2−
					IT (35%)	^147Dy
^147m2Dy	3407.2(8) keV			0.40(1) μs			(27/2−)
^148Dy	66	82	147.927150(11)	3.3(2) min	β^+	^148Tb	0+
^149Dy	66	83	148.927305(9)	4.20(14) min	β^+	^149Tb	7/2(−)
^149mDy	2661.1(4) keV			490(15) ms	IT (99.3%)	^149Dy	(27/2−)
					β^+ (.7%)	^149Tb
^150Dy	66	84	149.925585(5)	7.17(5) min	β^+ (64%)	^150Tb	0+
					α (36%)	^146Gd
^151Dy	66	85	150.926185(4)	17.9(3) min	β^+ (94.4%)	^151Tb	7/2(−)
					α (5.6%)	^147Gd
^152Dy	66	86	151.924718(6)	2.38(2) h	EC (99.9%)	^152Tb	0+
					α (.1%)	^148Gd
^153Dy	66	87	152.925765(5)	6.4(1) h	β^+ (99.99%)	^153Tb	7/2(−)
					α (.00939%)	^149Gd
^154Dy	66	88	153.924424(8)	3.0(15)×10^6 y	α	^150Gd	0+
					β^+β^+ (rare)	^154Gd
^155Dy	66	89	154.925754(13)	9.9(2) h	β^+	^155Tb	3/2−
^155mDy	234.33(3) keV			6(1) μs			11/2−
^156Dy	66	90	155.924283(7)	Observationally Stable[n 8]			0+	5.6(3)×10^−4
^157Dy	66	91	156.925466(7)	8.14(4) h	β^+	^157Tb	3/2−
^157m1Dy	161.99(3) keV			1.3(2) μs			9/2+
^157m2Dy	199.38(7) keV			21.6(16) ms	IT	^157Dy	11/2−
^158Dy	66	92	157.924409(4)	Observationally Stable[n 9]			0+	9.5(3)×10^−4
^159Dy	66	93	158.9257392(29)	144.4(2) d	EC	^159Tb	3/2−
^159mDy	352.77(14) keV			122(3) μs			11/2−
^160Dy	66	94	159.9251975(27)	Observationally Stable[n 10]			0+	0.02329(18)
^161Dy	66	95	160.9269334(27)	Observationally Stable[n 11]			5/2+	0.18889(42)
^162Dy	66	96	161.9267984(27)	Observationally Stable[n 12]			0+	0.25475(36)
^163Dy	66	97	162.9287312(27)	Stable[n 13][2]			5/2−	0.24896(42)
^164Dy	66	98	163.9291748(27)	Stable[n 14]			0+	0.28260(54)
^165Dy	66	99	164.9317033(27)	2.334(1) h	β^−	^165Ho	7/2+
^165mDy	108.160(3) keV			1.257(6) min	IT (97.76%)	^165Dy	1/2−
					β^− (2.24%)	^165Ho
^166Dy	66	100	165.9328067(28)	81.6(1) h	β^−	^166Ho	0+
^167Dy	66	101	166.93566(6)	6.20(8) min	β^−	^167Ho	(1/2−)
^168Dy	66	102	167.93713(15)	8.7(3) min	β^−	^168Ho	0+
^169Dy	66	103	168.94031(32)	39(8) s	β^−	^169Ho	(5/2−)
^170Dy	66	104	169.94239(21)#	30# s	β^−	^170Ho	0+
^171Dy	66	105	170.94620(32)#	6# s	β^−	^171Ho	7/2−#
^172Dy	66	106	171.94876(43)#	3# s	β^−	^172Ho	0+
^173Dy	66	107	172.95300(54)#	2# s	β^−	^173Ho	9/2+#

1. ^mDy – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition
   p:	Proton emission

6. Bold symbol as daughter – Daughter product is stable.
7. ( ) spin value – Indicates spin with weak assignment arguments.
8. Believed to undergo α decay to ¹⁵²Gd or β⁺β⁺ decay to ¹⁵⁶Gd with a half-life over 10¹⁸ years
9. Believed to undergo α decay to ¹⁵⁴Gd or β⁺β⁺ decay to ¹⁵⁸Gd
10. Believed to undergo α decay to ¹⁵⁶Gd
11. Believed to undergo α decay to ¹⁵⁷Gd
12. Believed to undergo α decay to ¹⁵⁸Gd
13. Can undergo bound-state β⁻ decay to ¹⁶³Ho with a half-life of 47 days when fully ionized
14. Heaviest theoretically stable nuclide

• Geologically exceptional samples are found associated with the Oklo natural nuclear fission reactor, in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.

Dysprosium-165

Radiopharmaceutical.

References

1. Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
2. M. Jung; et al. (1992-10-12). "First observation of bound-state β⁻ decay". Physical Review Letters. 69 (15): 2164–2167. Bibcode:1992PhRvL..69.2164J. doi:10.1103/PhysRevLett.69.2164. PMID 10046415.

• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.