Isotopes of dysprosium

Naturally occurring dysprosium (Dy) 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 (t_1/2 1.257 minutes), ^147mDy (t_1/2 55.7 seconds) and ^145mDy (t_1/2 13.6 seconds).

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.

Relative atomic mass: 162.500(1).

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)[1][n 1]	daughter isotope(s)[n 2]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^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 3]			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 4]			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 5]			0+	0.02329(18)
^161Dy	66	95	160.9269334(27)	Observationally Stable[n 6]			5/2+	0.18889(42)
^162Dy	66	96	161.9267984(27)	Observationally Stable[n 7]			0+	0.25475(36)
^163Dy	66	97	162.9287312(27)	Stable[n 8][n 9][2]			5/2−	0.24896(42)
^164Dy	66	98	163.9291748(27)	Stable[n 8]			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. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
3. Believed to undergo α decay to ¹⁵²Gd or β⁺β⁺ decay to ¹⁵⁶Gd with a half-life over 10¹⁸ years
4. Believed to undergo α decay to ¹⁵⁴Gd or β⁺β⁺ decay to ¹⁵⁸Gd
5. Believed to undergo α decay to ¹⁵⁶Gd
6. Believed to undergo α decay to ¹⁵⁷Gd
7. Believed to undergo α decay to ¹⁵⁸Gd
8. Theoretically capable of spontaneous fission
9. Can undergo bound-state β⁻ decay to ¹⁶³Ho with a half-life of 47 days when fully ionized

Notes

• Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

References

1. "Universal Nuclide Chart". nucleonica. (registration required (help)).
2. M. Jung; et al. (1992-10-12). "First observation of bound-state β⁻ decay". Physical Review Letters 69 (15): 2164–2167. doi:10.1103/PhysRevLett.69.2164. PMID 10046415.

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). 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:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylorr (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683.
  • M. E. Wieser (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. See editing notes on this article's talk page.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.