Thulium is a chemical element with symbol Tm and atomic number 69. It is the thirteenth and third-last element in the lanthanide series. Like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other compounds; because it occurs so late in the series, however, the +2 oxidation state is also stabilized by the nearly full 4f shell that results. In aqueous solution, like compounds of other late lanthanides, soluble thulium compounds form coordination complexes with nine water molecules.

In 1879, the Swedish chemist Per Teodor Cleve separated from the rare earth oxide erbia another two previously unknown components, which he called holmia and thulia; these were the oxides of holmium and thulium, respectively. A relatively pure sample of thulium metal was first obtained in 1911.

Thulium is the second-least abundant of the lanthanides, after radioactively unstable promethium which is only found in trace quantities on Earth. It is an easily workable metal with a bright silvery-gray luster. It is fairly soft and slowly tarnishes in air. Despite its high price and rarity, thulium is used as the radiation source in portable X-ray devices, and in some solid-state lasers. It has no significant biological role and is not particularly toxic.

Thulium,  69Tm
Thulium sublimed dendritic and 1cm3 cube
Pronunciation/ˈθjuːliəm/ (THEW-lee-əm)
Appearancesilvery gray
Standard atomic weight Ar, std(Tm)168.934218(6)[1]
Thulium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


Atomic number (Z)69
Groupgroup n/a
Periodperiod 6
Element category  lanthanide
Electron configuration[Xe] 4f13 6s2
Electrons per shell
2, 8, 18, 31, 8, 2
Physical properties
Phase at STPsolid
Melting point1818 K ​(1545 °C, ​2813 °F)
Boiling point2223 K ​(1950 °C, ​3542 °F)
Density (near r.t.)9.32 g/cm3
when liquid (at m.p.)8.56 g/cm3
Heat of fusion16.84 kJ/mol
Heat of vaporization191 kJ/mol
Molar heat capacity27.03 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1117 1235 1381 1570 (1821) (2217)
Atomic properties
Oxidation states+2, +3 (a basic oxide)
ElectronegativityPauling scale: 1.25
Ionization energies
  • 1st: 596.7 kJ/mol
  • 2nd: 1160 kJ/mol
  • 3rd: 2285 kJ/mol
Atomic radiusempirical: 176 pm
Covalent radius190±10 pm
Color lines in a spectral range
Spectral lines of thulium
Other properties
Natural occurrenceprimordial
Crystal structurehexagonal close-packed (hcp)
Hexagonal close packed crystal structure for thulium
Thermal expansionpoly: 13.3 µm/(m·K) (at r.t.)
Thermal conductivity16.9 W/(m·K)
Electrical resistivitypoly: 676 nΩ·m (at r.t.)
Magnetic orderingparamagnetic (at 300 K)
Magnetic susceptibility+25,500·10−6 cm3/mol (291 K)[2]
Young's modulus74.0 GPa
Shear modulus30.5 GPa
Bulk modulus44.5 GPa
Poisson ratio0.213
Vickers hardness470–650 MPa
Brinell hardness470–900 MPa
CAS Number7440-30-4
Namingafter Thule, a mythical region in Scandinavia
Discovery and first isolationPer Teodor Cleve (1879)
Main isotopes of thulium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
167Tm syn 9.25 d ε 167Er
168Tm syn 93.1 d ε 168Er
169Tm 100% stable
170Tm syn 128.6 d β 170Yb
171Tm syn 1.92 y β 171Yb


Physical properties

Pure thulium metal has a bright, silvery luster, which tarnishes on exposure to air. The metal can be cut with a knife,[3] as it has a Mohs hardness of 2 to 3; it is malleable and ductile.[4] Thulium is ferromagnetic below 32 K, antiferromagnetic between 32 and 56 K, and paramagnetic above 56 K.[5]

Thulium has two major allotropes: the tetragonal α-Tm and the more stable hexagonal β-Tm.[4]

Chemical properties

Thulium tarnishes slowly in air and burns readily at 150 °C to form thulium(III) oxide:

4 Tm + 3 O2 → 2 Tm2O3

Thulium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form thulium hydroxide:

2 Tm (s) + 6 H2O (l) → 2 Tm(OH)3 (aq) + 3 H2 (g)

Thulium reacts with all the halogens. Reactions are slow at room temperature, but are vigorous above 200 °C:

2 Tm (s) + 3 F2 (g) → 2 TmF3 (s) (white)
2 Tm (s) + 3 Cl2 (g) → 2 TmCl3 (s) (yellow)
2 Tm (s) + 3 Br2 (g) → 2 TmBr3 (s) (white)
2 Tm (s) + 3 I2 (g) → 2 TmI3 (s) (yellow)

Thulium dissolves readily in dilute sulfuric acid to form solutions containing the pale green Tm(III) ions, which exist as [Tm(OH2)9]3+ complexes:[6]

2 Tm (s) + 3 H2SO4 (aq) → 2 Tm3+ (aq) + 3 SO2−
(aq) + 3 H2 (g)

Thulium reacts with various metallic and non-metallic elements forming a range of binary compounds, including TmN, TmS, TmC2, Tm2C3, TmH2, TmH3, TmSi2, TmGe3, TmB4, TmB6 and TmB12. In those compounds, thulium exhibits valence states +2 and +3, however, the +3 state is most common and only this state has been observed in thulium solutions.[7] Thulium exists as a Tm3+ ion in solution. In this state, the thulium ion is surrounded by nine molecules of water.[3] Tm3+ ions exhibit a bright blue luminescence.[3]

Thulium's only known oxide is Tm2O3. This oxide is sometimes called "thulia".[8] Reddish-purple thulium(II) compounds can be made by the reduction of thulium(III) compounds. Examples of thulium(II) compounds include the halides (except the fluoride). Some hydrated thulium compounds, such as TmCl3·7H2O and Tm2(C2O4)3·6H2O are green or greenish-white.[9] Thulium dichloride reacts very vigorously with water. This reaction results in hydrogen gas and Tm(OH)3 exhibiting a fading reddish color. Combination of thulium and chalcogens results in thulium chalcogenides.[10]

Thulium reacts with hydrogen chloride to produce hydrogen gas and thulium chloride. With nitric acid it yields thulium nitrate, or Tm(NO3)3.[11]


The isotopes of thulium range from 145Tm to 179Tm. The primary decay mode before the most abundant stable isotope, 169Tm, is electron capture, and the primary mode after is beta emission. The primary decay products before 169Tm are element 68 (erbium) isotopes, and the primary products after are element 70 (ytterbium) isotopes.[12]

Thulium-169 is thulium's longest-lived and most abundant isotope. It is the only isotope of thulium that is thought to be stable, although it is predicted to undergo alpha decay to holmium-165 with a very long half-life.[3] After thulium-169, the next-longest-lived isotopes are thulium-171, which has a half-life of 1.92 years, and thulium-170, which has a half-life of 128.6 days. Most other isotopes have half-lives of a few minutes or less.[13] Thirty-five isotopes and 26 nuclear isomers of thulium have been detected.[3] Most isotopes of thulium lighter than 169 atomic mass units decay via electron capture or beta-plus decay, although some exhibit significant alpha decay or proton emission. Heavier isotopes undergo beta-minus decay.[13]


Thulium was discovered by Swedish chemist Per Teodor Cleve in 1879 by looking for impurities in the oxides of other rare earth elements (this was the same method Carl Gustaf Mosander earlier used to discover some other rare earth elements).[14] Cleve started by removing all of the known contaminants of erbia (Er2O3). Upon additional processing, he obtained two new substances; one brown and one green. The brown substance was the oxide of the element holmium and was named holmia by Cleve, and the green substance was the oxide of an unknown element. Cleve named the oxide thulia and its element thulium after Thule, an Ancient Greek place name associated with Scandinavia or Iceland. Thulium's atomic symbol was once Tu, but this was changed to Tm.[3][15]

Thulium was so rare that none of the early workers had enough of it to purify sufficiently to actually see the green color; they had to be content with spectroscopically observing the strengthening of the two characteristic absorption bands, as erbium was progressively removed. The first researcher to obtain nearly pure thulium was Charles James, a British expatriate working on a large scale at New Hampshire College in Durham. In 1911 he reported his results, having used his discovered method of bromate fractional crystallization to do the purification. He famously needed 15,000 purification operations to establish that the material was homogeneous.[16]

High-purity thulium oxide was first offered commercially in the late 1950s, as a result of the adoption of ion-exchange separation technology. Lindsay Chemical Division of American Potash & Chemical Corporation offered it in grades of 99% and 99.9% purity. The price per kilogram has oscillated between US$4,600 and $13,300 in the period from 1959 to 1998 for 99.9% purity, and it was second highest for lanthanides behind lutetium.[17][18]


Monazit - Madagaskar
Thulium is found in the mineral monazite

The element is never found in nature in pure form, but it is found in small quantities in minerals with other rare earths. Thulium is often found with minerals containing yttrium and gadolinium. In particular, thulium occurs in the mineral gadolinite.[19] However, thulium also occurs in the minerals monazite, xenotime, and euxenite. Thulium has not been found in prevalence over the other rare earths in any mineral yet.[20] Its abundance in the Earth's crust is 0.5 mg/kg by weight and 50 parts per billion by moles. Thulium makes up approximately 0.5 parts per million of soil, although this value can range from 0.4 to 0.8 parts per million. Thulium makes up 250 parts per quadrillion of seawater.[3] In the solar system, thulium exists in concentrations of 200 parts per trillion by weight and 1 part per trillion by moles.[11] Thulium ore occurs most commonly in China. However, Australia, Brazil, Greenland, India, Tanzania, and the United States also have large reserves of thulium. Total reserves of thulium are approximately 100,000 tonnes. Thulium is the least abundant lanthanide on earth except for promethium.[3]


Thulium is principally extracted from monazite ores (~0.007% thulium) found in river sands, through ion-exchange. Newer ion-exchange and solvent-extraction techniques have led to easier separation of the rare earths, which has yielded much lower costs for thulium production. The principal sources today are the ion adsorption clays of southern China. In these, where about two-thirds of the total rare-earth content is yttrium, thulium is about 0.5% (or about tied with lutetium for rarity). The metal can be isolated through reduction of its oxide with lanthanum metal or by calcium reduction in a closed container. None of thulium's natural compounds are commercially important. Approximately 50 tonnes per year of thulium oxide are produced.[3] In 1996, thulium oxide cost US$20 per gram, and in 2005, 99%-pure thulium metal powder cost US$70 per gram.[4]


Thulium has a few applications:


Holmium-chromium-thulium triple-doped yttrium aluminum garnet (Ho:Cr:Tm:YAG, or Ho,Cr,Tm:YAG) is an active laser medium material with high efficiency. It lases at 2080 nm and is widely used in military applications, medicine, and meteorology. Single-element thulium-doped YAG (Tm:YAG) lasers operate at 2,01 μm.[21] The wavelength of thulium-based lasers is very efficient for superficial ablation of tissue, with minimal coagulation depth in air or in water. This makes thulium lasers attractive for laser-based surgery.[22]

X-ray source

Despite its high cost, portable X-ray devices use thulium that has been bombarded in a nuclear reactor as a radiation source. These sources have a useful life of about one year, as tools in medical and dental diagnosis, as well as to detect defects in inaccessible mechanical and electronic components. Such sources do not need extensive radiation protection – only a small cup of lead.[23]

Thulium-170 is gaining popularity as an X-ray source for cancer treatment via brachytherapy.[24] This isotope has a half-life of 128.6 days and five major emission lines of comparable intensity (at 7.4, 51.354, 52.389, 59.4 and 84.253 keV).[25] Thulium-170 is one of the four most popular radioisotopes for use in industrial radiography.[26]


Thulium has been used in high-temperature superconductors similarly to yttrium. Thulium potentially has use in ferrites, ceramic magnetic materials that are used in microwave equipment.[23] Thulium is also similar to scandium in that it is used in arc lighting for its unusual spectrum, in this case, its green emission lines, which are not covered by other elements.[27] Because thulium fluoresces with a blue color when exposed to ultraviolet light, thulium is put into euro banknotes as a measure against counterfeiting.[28] The blue fluorescence of Tm-doped calcium sulfate has been used in personal dosimeters for visual monitoring of radiation.[3] Tm-doped halides in which Tm is in its 2+ valence state, are promising luminescent materials that can make efficient electricity generating windows based on the principle of a luminescent solar concentrator, possible.[29]

Biological role and precautions

Soluble thulium salts are mildly toxic, but insoluble thulium salts are completely nontoxic.[3] When injected, thulium can cause degeneration of the liver and spleen and can also cause hemoglobin concentration to fluctuate. Liver damage from thulium is more prevalent in male mice than female mice. Despite this, thulium has a low level of toxicity. In humans, thulium occurs in the highest amounts in the liver, kidneys and bones. Humans typically consume several micrograms of thulium per year. The roots of plants do not take up thulium, and the dry weight of vegetables usually contains one part per billion of thulium.[3] Thulium dust and powder are toxic upon inhalation or ingestion and can cause explosions.

See also

  • Thulium compounds


  1. ^ Meija, J.; 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. ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
  3. ^ a b c d e f g h i j k l Emsley, John (2001). Nature's building blocks: an A-Z guide to the elements. US: Oxford University Press. pp. 442–443. ISBN 0-19-850341-5.
  4. ^ a b c Hammond, C. R. (2000). "The Elements". Handbook of Chemistry and Physics (81st ed.). CRC press. ISBN 0-8493-0481-4.
  5. ^ Jackson, M. (2000). "Magnetism of Rare Earth" (PDF). The IRM quarterly. 10 (3): 1.
  6. ^ "Chemical reactions of Thulium". Webelements. Retrieved 2009-06-06.
  7. ^ Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. p. 934. ISBN 0-07-049439-8.
  8. ^ Krebs, Robert E (2006). The History and Use of Our Earth's Chemical Elements: A Reference Guide. ISBN 978-0-313-33438-2.
  9. ^ Eagleson, Mary (1994). Concise Encyclopedia Chemistry. Walter de Gruyter. p. 1105. ISBN 978-3-11-011451-5.
  10. ^ Emeléus, H. J.; Sharpe, A. G. (1977). Advances in Inorganic Chemistry and Radiochemistry. Academic Press. ISBN 978-0-08-057869-9.
  11. ^ a b Thulium. Retrieved on 2013-03-29.
  12. ^ Lide, David R. (1998). "Section 11, Table of the Isotopes". Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0594-2.
  13. ^ a b Sonzogni, Alejandro. "Untitled". National Nuclear Data Center. Retrieved 2013-02-20.
  14. ^ See:
    • Cleve, P. T. (1879). "Sur deux nouveaux éléments dans l'erbine" [Two new elements in the oxide of erbium]. Comptes rendus (in French). 89: 478–480. Cleve named thulium on p. 480: "Pour le radical de l'oxyde placé entre l'ytterbine et l'erbine, qui est caractérisé par la bande x dans la partie rouge du spectre, je propose la nom de thulium, dérivé de Thulé, le plus ancien nom de la Scandinavie." (For the radical of the oxide located between the oxides of ytterbium and erbium, which is characterized by the x band in the red part of the spectrum, I propose the name of "thulium", [which is] derived from Thule, the oldest name of Scandinavia.)
    • Cleve, P. T. (1879). "Sur l'erbine" [On the oxide of erbium]. Comptes rendus (in French). 89: 708–709.
    • Cleve, P. T. (1880). "Sur le thulium" [On thulium]. Comptes rendus (in French). 91: 328–329.
  15. ^ Eagleson, Mary (1994). Concise Encyclopedia Chemistry. Walter de Gruyter. p. 1061. ISBN 978-3-11-011451-5.
  16. ^ James, Charles (1911). "Thulium I". Journal of the American Chemical Society. 33 (8): 1332–1344. doi:10.1021/ja02221a007.
  17. ^ Hedrick, James B. "Rare-Earth Metals" (PDF). U.S. Geological Survey. Retrieved 2009-06-06.
  18. ^ Castor, Stephen B. & Hedrick, James B. "Rare Earth Elements" (PDF). Retrieved 2009-06-06.
  19. ^ Walker, Perrin & Tarn, William H. (2010). CRC Handbook of Metal Etchants. CRC Press. pp. 1241–. ISBN 978-1-4398-2253-1.
  20. ^ Hudson Institute of Mineralogy (1993–2018). "". Retrieved 14 January 2018.
  21. ^ Koechner, Walter (2006). Solid-state laser engineering. Springer. p. 49. ISBN 0-387-29094-X.
  22. ^ Duarte, Frank J. (2008). Tunable laser applications. CRC Press. p. 214. ISBN 1-4200-6009-0.
  23. ^ a b Gupta, C. K. & Krishnamurthy, Nagaiyar (2004). Extractive metallurgy of rare earths. CRC Press. p. 32. ISBN 0-415-33340-7.
  24. ^ Krishnamurthy, Devan; Vivian Weinberg; J. Adam M. Cunha; I-Chow Hsu; Jean Pouliot (2011). "Comparison of high–dose rate prostate brachytherapy dose distributions with iridium-192, ytterbium-169, and thulium-170 sources". Brachytherapy. 10 (6): 461–465. doi:10.1016/j.brachy.2011.01.012. PMID 21397569.
  25. ^ Ayoub, Amal Hwaree et al. Development of New Tm-170 Radioactive Seeds for Brachytherapy, Department of Biomedical Engineering, Ben-Gurion University of the Negev
  26. ^ Raj, Baldev; Venkataraman, Balu (2004). Practical Radiography. ISBN 978-1-84265-188-9.
  27. ^ Gray, Theodore W. & Mann, Nick (2009). The Elements: A Visual Exploration of Every Known Atom In The Universe. Black Dog & Leventhal Publishers. p. 159. ISBN 978-1-57912-814-2.
  28. ^ Wardle, Brian (2009-11-06). Principles and Applications of Photochemistry. p. 75. ISBN 978-0-470-71013-5.
  29. ^ ten Kate, O.M.; Krämer, K.W.; van der Kolk, E. (2015). "Efficient luminescent solar concentrators based on self-absorption free, Tm2+ doped halides". Solar Energy Materials & Solar Cells. 140: 115–120. doi:10.1016/j.solmat.2015.04.002.

External links

Anything But Joey

Anything But Joey was a pop-rock band from the Kansas City area. For the majority of its existence, the band was made up of high school friends Matt Groebe (lead vocals), Drew Scofield (bass/backing vocals), Jeff Polaschek (drums), and Bryan Chesen (guitar).


Erbium is a chemical element with symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements. It is a lanthanide, a rare earth element, originally found in the gadolinite mine in Ytterby in Sweden, from which it got its name.

Erbium's principal uses involve its pink-colored Er3+ ions, which have optical fluorescent properties particularly useful in certain laser applications. Erbium-doped glasses or crystals can be used as optical amplification media, where Er3+ ions are optically pumped at around 980 or 1480 nm and then radiate light at 1530 nm in stimulated emission. This process results in an unusually mechanically simple laser optical amplifier for signals transmitted by fiber optics. The 1550 nm wavelength is especially important for optical communications because standard single mode optical fibers have minimal loss at this particular wavelength.

In addition to optical fiber amplifier-lasers, a large variety of medical applications (i.e. dermatology, dentistry) rely on the erbium ion's 2940 nm emission (see Er:YAG laser) when lit at another wavelength, which is highly absorbed in water in tissues, making its effect very superficial. Such shallow tissue deposition of laser energy is helpful in laser surgery, and for the efficient production of steam which produces enamel ablation by common types of dental laser.


Fraxel Laser Treatment is a line of non-surgical lasers for facial rejuvenation developed by Solta Medical in 2000 with the help of Dr. Cameron Rokhsar in New York.

Fraxel lasers cause fractional photothermolysis for skin resurfacing to treat a range of skin conditions. Different fraxel systems use 10,600 nm CO2, 1550 nm Erbium, and 1927 nm Thulium lasers.

Inorganic compounds by element

This is a list of common inorganic and organometallic compounds of each element. Compounds are listed alphabetically by their chemical element name rather than by symbol, as in list of inorganic compounds.

Isotopes of erbium

Naturally occurring erbium (68Er) is composed of 6 stable isotopes, with 166Er being the most abundant (33.503% natural abundance). Thirty radioisotopes have been characterized with between 74 and 108 neutrons, or 142 to 177 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 13 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 176.9541 u (177Er). 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.

Isotopes of thulium

Naturally occurring thulium (69Tm) is composed of 1 stable isotope, 169Tm (100% natural abundance). Thirty-four radioisotopes have been characterized, with the most stable being 171Tm with a half-life of 1.92 years, 170Tm with a half-life of 128.6 days, 168Tm with a half-life of 93.1 days, and 167Tm with a half-life of 9.25 days. All of the remaining radioactive isotopes have half-lives that are less than 64 hours, and the majority of these have half-lives that are less than 2 minutes. This element also has 26 meta states, with the most stable being 164mTm (t1/2 5.1 minutes), 160mTm (t1/2 74.5 seconds) and 155mTm (t1/2 45 seconds).

The isotopes of thulium range in atomic weight from 144.97007 u (145Tm) to 178.95534 u (179Tm). The primary decay mode before the most abundant stable isotope, 169Tm, is electron capture, and the primary mode after is beta emission. The primary decay products before 169Tm are erbium isotopes, and the primary products after are ytterbium isotopes.

Isotopes of ytterbium

Naturally occurring Ytterbium (70Yb) is composed of 7 stable isotopes, 168Yb, 170Yb, 171Yb, 172Yb, 173Yb, 174Yb, and 176Yb, with 174Yb being the most abundant (31.83% natural abundance). Twenty-seven radioisotopes have been characterized, with the most stable being 169Yb with a half-life of 32.026 days, 175Yb with a half-life of 4.185 days, and 166Yb with a half-life of 56.7 hours. All of the remaining radioactive isotopes have half-lives that are less than 2 hours, and the majority of these have half-lives that are less than 20 minutes. This element also has 12 meta states, with the most stable being 169mYb (t1/2 46 seconds).

The isotopes of ytterbium range in atomic weight from 147.967 u (148Yb) to 180.9562 u (181Yb). The primary decay mode before the most abundant stable isotope, 174Yb is electron capture, and the primary mode after is beta emission. The primary decay products before 174Yb are isotopes of thulium, and the primary products after are isotopes of lutetium. Of interest to modern quantum optics, the different ytterbium isotopes follow either Bose–Einstein statistics or Fermi–Dirac statistics, leading to interesting behavior in optical lattices.

Laser lithotripsy

Laser lithotripsy is a surgical procedure to remove stones from urinary tract, i.e., kidney, ureter, bladder, or urethra.

List of radioactive isotopes by half-life

This is a list of radioactive isotopes ordered by half-life from shortest to longest.

Major actinide

Major actinides is a term used in the nuclear power industry that refers to the plutonium and uranium present in used nuclear fuel, as opposed to the minor actinides neptunium, americium, curium, berkelium, and californium.


Mendelevium is a synthetic element with chemical symbol Md (formerly Mv) and atomic number 101. A metallic radioactive transuranic element in the actinide series, it is the first element that currently cannot be produced in macroscopic quantities through neutron bombardment of lighter elements. It is the third-to-last actinide and the ninth transuranic element. It can only be produced in particle accelerators by bombarding lighter elements with charged particles. A total of sixteen mendelevium isotopes are known, the most stable being 258Md with a half-life of 51 days; nevertheless, the shorter-lived 256Md (half-life 1.17 hours) is most commonly used in chemistry because it can be produced on a larger scale.

Mendelevium was discovered by bombarding einsteinium with alpha particles in 1955, the same method still used to produce it today. It was named after Dmitri Mendeleev, father of the periodic table of the chemical elements. Using available microgram quantities of the isotope einsteinium-253, over a million mendelevium atoms may be produced each hour. The chemistry of mendelevium is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts of produced mendelevium and all of its isotopes having relatively short half-lives, there are currently no uses for it outside basic scientific research.

Per Teodor Cleve

Per Teodor Cleve (10 February 1840 – 18 June 1905) was a Swedish chemist, biologist, mineralogist and oceanographer. He is best known for his discovery of the chemical elements holmium and thulium.Born in Stockholm in 1840, Cleve earned his BSc and PhD from Uppsala University in 1863 and 1868, respectively. After receiving his PhD, he became an assistant professor of chemistry at the university. He later became professor of general and agricultural chemistry. In 1874 he theorised that didymium was in fact two elements; this theory was confirmed in 1885 when Carl Auer von Welsbach discovered neodymium and praseodymium.

In 1879 Cleve discovered holmium and thulium. His other contributions to chemistry include the discovery of aminonaphthalenesulfonic acids, also known as Cleve's acids. From 1890 on he focused on biological studies. He developed a method of determining the age and order of late glacial and postglacial deposits from the types of diatom fossils in the deposits, and wrote a seminal text in the field of oceanography. He died in 1905 at age 65.

Proton emission

Proton emission (also known as proton radioactivity) is a rare type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state (or a low-lying isomer) of very proton-rich nuclei, in which case the process is very similar to alpha decay.

For a proton to escape a nucleus, the proton separation energy must be negative - the proton is therefore unbound, and tunnels out of the nucleus in a finite time. Proton emission is not seen in naturally occurring isotopes; proton emitters can be produced via nuclear reactions, usually using linear particle accelerators.

Although prompt (i.e. not beta-delayed) proton emission was observed from an isomer in cobalt-53 as early as 1969, no other proton-emitting states were found until 1981, when the proton radioactive ground states of lutetium-151 and thulium-147 were observed at experiments at the GSI in West Germany. Research in the field flourished after this breakthrough, and to date more than 25 isotopes have been found to exhibit proton emission. The study of proton emission has aided the understanding of nuclear deformation, masses, and structure, and it is a pure example of quantum tunneling.

In 2002, the simultaneous emission of two protons was observed from the nucleus iron-45 in experiments at GSI and GANIL (Grand Accélérateur National d'Ions Lourds at Caen). In 2005 it was experimentally determined (at the same facility) that zinc-54 can also undergo double proton decay.

Solid-state laser

A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid such as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class from solid-state lasers (see Laser diode).

Thulium(III) bromide

Thulium(III) bromide is a crystalline compound of one thulium atom and three bromine atoms. It is a white powder at room temperature. It is hygroscopic.

Thulium(III) chloride

Thulium(III) chloride or thulium trichloride is the chemical compound composed of thulium and chlorine with the formula TmCl3. It forms yellow crystals. Thulium(III) chloride has the YCl3 (AlCl3) layer structure with octahedral thulium ions.

Thulium(III) oxide

Thulium(III) oxide is a pale green solid compound, with the formula Tm2O3. It was first isolated in 1879 from an impure sample of erbia by Per Teodor Cleve, who named it thulia.

It can be prepared in the laboratory by burning thulium metal in air, or by decomposition of their oxoacid salts, such as thulium nitrate.


Ytterbium is a chemical element with symbol Yb and atomic number 70. It is the fourteenth and penultimate element in the lanthanide series, which is the basis of the relative stability of its +2 oxidation state. However, like the other lanthanides, its most common oxidation state is +3, as in its oxide, halides, and other compounds. In aqueous solution, like compounds of other late lanthanides, soluble ytterbium compounds form complexes with nine water molecules. Because of its closed-shell electron configuration, its density and melting and boiling points differ significantly from those of most other lanthanides.

In 1878, the Swiss chemist Jean Charles Galissard de Marignac separated from the rare earth "erbia" another independent component, which he called "ytterbia", for Ytterby, the village in Sweden near where he found the new component of erbium. He suspected that ytterbia was a compound of a new element that he called "ytterbium" (in total, four elements were named after the village, the others being yttrium, terbium and erbium). In 1907, the new earth "lutecia" was separated from ytterbia, from which the element "lutecium" (now lutetium) was extracted by Georges Urbain, Carl Auer von Welsbach, and Charles James. After some discussion, Marignac's name "ytterbium" was retained. A relatively pure sample of the metal was not obtained until 1953. At present, ytterbium is mainly used as a dopant of stainless steel or active laser media, and less often as a gamma ray source.

Natural ytterbium is a mixture of seven stable isotopes, which altogether are present at concentrations of 3 parts per million. This element is mined in China, the United States, Brazil, and India in form of the minerals monazite, euxenite, and xenotime. The ytterbium concentration is low because it is found only among many other rare earth elements; moreover, it is among the least abundant. Once extracted and prepared, ytterbium is somewhat hazardous as an eye and skin irritant. The metal is a fire and explosion hazard.

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