Last updated

Thulium, 69Tm
Thulium sublimed dendritic and 1cm3 cube.jpg
Pronunciation /ˈθjliəm/ (THEW-lee-əm)
Appearancesilvery gray
Standard atomic weight Ar°(Tm)
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
Group f-block groups (no number)
Period period 6
Block   f-block
Electron configuration [ Xe ] 4f13 6s2
Electrons per shell2, 8, 18, 31, 8, 2
Physical properties
Phase at  STP solid
Melting point 1818  K (1545 °C,2813 °F)
Boiling point 2223 K(1950 °C,3542 °F)
Density (at 20° C)9.320 g/cm3 [3]
when liquid (at  m.p.)8.56 g/cm3
Heat of fusion 16.84  kJ/mol
Heat of vaporization 191 kJ/mol
Molar heat capacity 27.03 J/(mol·K)
Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)1117123513811570(1821)(2217)
Atomic properties
Oxidation states 0, [4] +1, [5] +2, +3 (a  basic oxide)
Electronegativity Pauling scale: 1.25
Ionization energies
  • 1st: 596.7 kJ/mol
  • 2nd: 1160 kJ/mol
  • 3rd: 2285 kJ/mol
Atomic radius empirical:176  pm
Covalent radius 190±10 pm
Thulium spectrum visible.png
Spectral lines of thulium
Other properties
Natural occurrence primordial
Crystal structure hexagonal close-packed (hcp)(hP2)
Lattice constants
Hexagonal close packed.svg
a = 353.77 pm
c = 555.39 pm (at 20 °C) [3]
Thermal expansion poly: 13.3 µm/(m⋅K)(at r.t.)
Thermal conductivity 16.9 W/(m⋅K)
Electrical resistivity poly: 676 nΩ⋅m(at r.t.)
Magnetic ordering paramagnetic (at 300 K)
Molar magnetic susceptibility +25500×10−6 cm3/mol(291 K) [6]
Young's modulus 74.0 GPa
Shear modulus 30.5 GPa
Bulk modulus 44.5 GPa
Poisson ratio 0.213
Vickers hardness 470–650 MPa
Brinell hardness 470–900 MPa
CAS Number 7440-30-4
Namingafter Thule, a mythical region in Scandinavia
Discovery and first isolation Per Teodor Cleve (1879)
Isotopes of thulium
Main isotopes [7] Decay
abun­dance half-life (t1/2) mode pro­duct
167Tm synth 9.25 d ε 167Er
168Tmsynth93.1 d β+ 168Er
169Tm100% stable
170Tm synth128.6 d β 170Yb
171Tmsynth1.92 yβ 171Yb
Symbol category class.svg  Category: Thulium
| references

Thulium is a chemical element; it has symbol Tm and atomic number 69. It is the thirteenth element in the lanthanide series of metals. It is the second-least abundant lanthanide in the Earth's crust, after radioactively unstable promethium. 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 a dopant in solid-state lasers, and as the radiation source in some portable X-ray devices. It has no significant biological role and is not particularly toxic.


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

Like the other lanthanides, its most common oxidation state is +3, seen in its oxide, halides and other compounds. In aqueous solution, like compounds of other late lanthanides, soluble thulium compounds form coordination complexes with nine water molecules.


Physical properties

Pure thulium metal has a bright, silvery luster, which tarnishes on exposure to air. The metal can be cut with a knife, [8] as it has a Mohs hardness of 2 to 3; it is malleable and ductile. [9] Thulium is ferromagnetic below 32 K, antiferromagnetic between 32 and 56 K, and paramagnetic above 56 K. [10]

Thulium has two major allotropes: the tetragonal α-Tm and the more stable hexagonal β-Tm. [9]

Chemical properties

Thulium tarnishes slowly in air and burns readily at 150  °C to form thulium(III) oxide: [11]

4Tm + 3O2 → 2Tm2O3

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

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

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

2Tm(s) + 3F2(g) → 2TmF3(s) (white)
2Tm(s) + 3Cl2(g) → 2TmCl3(s) (yellow)
2Tm(s) + 3Br2(g) → 2TmBr3(s) (white)
2Tm(s) + 3I2(g) → 2TmI3(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: [12]

2Tm(s) + 3H2SO4(aq) → 2Tm3+(aq) + 3SO2−4(aq) + 3H2(aq)

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.[ citation needed ] Like most lanthanides, the +3 state is most common and is the only state observed in thulium solutions. [13] Thulium exists as a Tm3+ ion in solution. In this state, the thulium ion is surrounded by nine molecules of water. [8] Tm3+ ions exhibit a bright blue luminescence. [8] Because it occurs late in the series, the +2 oxidation state can also exist, stabilized by the nearly full 4f electron shell, but occurs only in solids.[ citation needed ]

Thulium's only known oxide is Tm2O3. This oxide is sometimes called "thulia". [14] 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. [15] Thulium dichloride reacts very vigorously with water. This reaction results in hydrogen gas and Tm(OH)3 exhibiting a fading reddish color.[ citation needed ] Combination of thulium and chalcogens results in thulium chalcogenides. [16]

Thulium reacts with hydrogen chloride to produce hydrogen gas and thulium chloride. With nitric acid it yields thulium nitrate, or Tm(NO3)3. [17]


The isotopes of thulium range from 144Tm to 183Tm. [7] [18] 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. [19]

Thulium-169 is thulium's only primordial isotope and is the only isotope of thulium that is thought to be stable; it is predicted to undergo alpha decay to holmium-165 with a very long half-life. [8] [20] The longest-lived radioisotopes 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. [21] In total, 40 isotopes and 26 nuclear isomers of thulium have been detected. [8] 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. [21]


Per Teodor Cleve, the scientist who discovered thulium as well as holmium. Per Teodor Cleve c1885.jpg
Per Teodor Cleve, the scientist who discovered thulium as well as holmium.

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). [22] Cleve started by removing all of the known contaminants of erbia ( Er 2 O 3). 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 initially Tu, but later[ when? ] changed to Tm.[ why? ] [8] [23] [24] [25] [26] [27] [28]

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, USA. 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. [29]

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 oscillated between US$4,600 and $13,300 in the period from 1959 to 1998 for 99.9% purity, and it was the second highest for the lanthanides behind lutetium. [30] [31]


Thulium is found in the mineral monazite Monazit - Madagaskar.jpg
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. [32] However, like many other lanthanides, 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. [33] Its abundance in the Earth's crust is 0.5 mg/kg by weight. [34] 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. [8] In the Solar System, thulium exists in concentrations of 200 parts per trillion by weight and 1 part per trillion by moles. [17] 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 the radioactive promethium. [8]


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. [8] In 1996, thulium oxide cost US$20 per gram, and in 2005, 99%-pure thulium metal powder cost US$70 per gram. [9]



Holmium-chromium-thulium triple-doped yttrium aluminium garnet (Ho:Cr:Tm:YAG, or Ho,Cr,Tm:YAG) is an active laser medium material with high efficiency. It lases at 2080 nm in the infrared and is widely used in military applications, medicine, and meteorology. Single-element thulium-doped YAG (Tm:YAG) lasers operate at 2010 nm. [35] 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. [36]

X-ray source

Despite its high cost, portable X-ray devices use thulium that has been bombarded with neutrons in a nuclear reactor to produce the isotope Thulium-170, having 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). These radioactive 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. [37] They are among the most popular radiation sources for use in industrial radiography. [38] Thulium-170 is gaining popularity as an X-ray source for cancer treatment via brachytherapy (sealed source radiation therapy). [39] [40]


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. [37] 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. [41] Because thulium fluoresces with a blue color when exposed to ultraviolet light, thulium is put into euro banknotes as a measure against counterfeiting. [42] The blue fluorescence of Tm-doped calcium sulfate has been used in personal dosimeters for visual monitoring of radiation. [8] Tm-doped halides in which Tm is in its 2+ oxidation state are luminescent materials that are proposed for electric power generating windows based on the principle of a luminescent solar concentrator. [43]

Biological role and precautions

Soluble thulium salts are mildly toxic, but insoluble thulium salts are completely nontoxic. [8] 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. [44] [45] 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 matter of vegetables usually contains one part per billion of thulium. [8] Thulium dust and powder are toxic upon inhalation or ingestion and can cause explosions.[ citation needed ]

See also

Related Research Articles

<span class="mw-page-title-main">Dysprosium</span> Chemical element, symbol Dy and atomic number 66

Dysprosium is a chemical element; it has symbol Dy and atomic number 66. It is a rare-earth element in the lanthanide series with a metallic silver luster. Dysprosium is never found in nature as a free element, though, like other lanthanides, it is found in various minerals, such as xenotime. Naturally occurring dysprosium is composed of seven isotopes, the most abundant of which is 164Dy.

<span class="mw-page-title-main">Europium</span> Chemical element, symbol Eu and atomic number 63

Europium is a chemical element; it has symbol Eu and atomic number 63. Europium is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. It is the most chemically reactive, least dense, and softest of the lanthanide elements. It is soft enough to be cut with a knife. Europium was isolated in 1901 and named after the continent of Europe. Europium usually assumes the oxidation state +3, like other members of the lanthanide series, but compounds having oxidation state +2 are also common. All europium compounds with oxidation state +2 are slightly reducing. Europium has no significant biological role and is relatively non-toxic compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds. Europium is one of the rarest of the rare-earth elements on Earth.

<span class="mw-page-title-main">Erbium</span> Chemical element, symbol Er and atomic number 68

Erbium is a chemical element; it has 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, Sweden, which is the source of the element's name.

<span class="mw-page-title-main">Holmium</span> Chemical element, symbol Ho and atomic number 67

Holmium is a chemical element; it has symbol Ho and atomic number 67. It is a rare-earth element and the eleventh member of the lanthanide series. It is a relatively soft, silvery, fairly corrosion-resistant and malleable metal. Like many other lanthanides, holmium is too reactive to be found in native form, as pure holmium slowly forms a yellowish oxide coating when exposed to air. When isolated, holmium is relatively stable in dry air at room temperature. However, it reacts with water and corrodes readily, and also burns in air when heated.

<span class="mw-page-title-main">Lanthanum</span> Chemical element, symbol La and atomic number 57

Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. Lanthanum is traditionally counted among the rare earth elements. Like most other rare earth elements, the usual oxidation state is +3, although some compounds are known with an oxidation state of +2. Lanthanum has no biological role in humans but is essential to some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity.

<span class="mw-page-title-main">Lutetium</span> Chemical element, symbol Lu and atomic number 71

Lutetium is a chemical element; it has symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted among the rare earth elements; it can also be classified as the first element of the 6th-period transition metals.

The lanthanide or lanthanoid series of chemical elements comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals. Lutetium is also sometimes considered a lanthanide, despite being a d-block element and a transition metal.

<span class="mw-page-title-main">Neodymium</span> Chemical element, symbol Nd and atomic number 60

Neodymium is a chemical element; it has symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth metals. It is a hard, slightly malleable, silvery metal that quickly tarnishes in air and moisture. When oxidized, neodymium reacts quickly producing pink, purple/blue and yellow compounds in the +2, +3 and +4 oxidation states. It is generally regarded as having one of the most complex spectra of the elements. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach, who also discovered praseodymium. It is present in significant quantities in the minerals monazite and bastnäsite. Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Neodymium is fairly common—about as common as cobalt, nickel, or copper—and is widely distributed in the Earth's crust. Most of the world's commercial neodymium is mined in China, as is the case with many other rare-earth metals.

<span class="mw-page-title-main">Promethium</span> Chemical element, symbol Pm and atomic number 61

Promethium is a chemical element; it has symbol Pm and atomic number 61. All of its isotopes are radioactive; it is extremely rare, with only about 500–600 grams naturally occurring in Earth's crust at any given time. Promethium is one of only two radioactive elements that are followed in the periodic table by elements with stable forms, the other being technetium. Chemically, promethium is a lanthanide. Promethium shows only one stable oxidation state of +3.

<span class="mw-page-title-main">Scandium</span> Chemical element, symbol Sc and atomic number 21

Scandium is a chemical element; it has symbol Sc and atomic number 21. It is a silvery-white metallic d-block element. Historically, it has been classified as a rare-earth element, together with yttrium and the lanthanides. It was discovered in 1879 by spectral analysis of the minerals euxenite and gadolinite from Scandinavia.

<span class="mw-page-title-main">Terbium</span> Chemical element, symbol Tb and atomic number 65

Terbium is a chemical element; it has the symbol Tb and atomic number 65. It is a silvery-white, rare earth metal that is malleable, and ductile. The ninth member of the lanthanide series, terbium is a fairly electropositive metal that reacts with water, evolving hydrogen gas. Terbium is never found in nature as a free element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime and euxenite.

<span class="mw-page-title-main">Ytterbium</span> Chemical element, symbol Yb and atomic number 70

Ytterbium is a chemical element; it has symbol Yb and atomic number 70. It is a metal, the fourteenth and penultimate element in the lanthanide series, which is the basis of the relative stability of its +2 oxidation state. 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, melting point and boiling point are much lower than those of most other lanthanides.

A period 5 element is one of the chemical elements in the fifth row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fifth period contains 18 elements, beginning with rubidium and ending with xenon. As a rule, period 5 elements fill their 5s shells first, then their 4d, and 5p shells, in that order; however, there are exceptions, such as rhodium.

<span class="mw-page-title-main">Praseodymium</span> Chemical element, symbol Pr and atomic number 59

Praseodymium is a chemical element; it has symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for its magnetic, electrical, chemical, and optical properties. It is too reactive to be found in native form, and pure praseodymium metal slowly develops a green oxide coating when exposed to air.

<span class="mw-page-title-main">Group 3 element</span> Group of chemical elements

Group 3 is the first group of transition metals in the periodic table. This group is closely related to the rare-earth elements. It contains the four elements scandium (Sc), yttrium (Y), lutetium (Lu), and lawrencium (Lr). The group is also called the scandium group or scandium family after its lightest member.

<span class="mw-page-title-main">Holmium(III) oxide</span> Chemical compound

Holmium(III) oxide, or holmium oxide is a chemical compound of a rare-earth element holmium and oxygen with the formula Ho2O3. Together with dysprosium(III) oxide (Dy2O3), holmium oxide is one of the most powerfully paramagnetic substances known. The oxide, also called holmia, occurs as a component of the related erbium oxide mineral called erbia. Typically, the oxides of the trivalent lanthanides coexist in nature, and separation of these components requires specialized methods. Holmium oxide is used in making specialty colored glasses. Glass containing holmium oxide and holmium oxide solutions have a series of sharp optical absorption peaks in the visible spectral range. They are therefore traditionally used as a convenient calibration standard for optical spectrophotometers.

<span class="mw-page-title-main">Carl Axel Arrhenius</span> Swedish chemist (1757–1824)

Carl Axel Arrhenius was a Swedish military officer, amateur geologist, and chemist. He is best known for his discovery of the mineral ytterbite in 1787.

<span class="mw-page-title-main">Yttrium</span> Chemical element, symbol Y and atomic number 39

Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element. 89Y is the only stable isotope and the only isotope found in the Earth's crust.

<span class="mw-page-title-main">Cerium</span> Chemical element, symbol Ce and atomic number 58

Cerium is a chemical element; it has symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the oxidation state of +3 characteristic of the series, it also has a stable +4 state that does not oxidize water. It is also considered one of the rare-earth elements. Cerium has no known biological role in humans but is not particularly toxic, except with intense or continued exposure.

Erbium compounds are compounds containing the element erbium (Er). These compounds are usually dominated by erbium in the +3 oxidation state, although the +2, +1 and 0 oxidation states have also been reported.


  1. "Standard Atomic Weights: Thulium". CIAAW. 2021.
  2. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN   1365-3075.
  3. 1 2 Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN   978-1-62708-155-9.
  4. Yttrium and all lanthanides except Ce and Pm have been observed in the oxidation state 0 in bis(1,3,5-tri-t-butylbenzene) complexes, see Cloke, F. Geoffrey N. (1993). "Zero Oxidation State Compounds of Scandium, Yttrium, and the Lanthanides". Chem. Soc. Rev. 22: 17–24. doi:10.1039/CS9932200017. and Arnold, Polly L.; Petrukhina, Marina A.; Bochenkov, Vladimir E.; Shabatina, Tatyana I.; Zagorskii, Vyacheslav V.; Cloke (2003-12-15). "Arene complexation of Sm, Eu, Tm and Yb atoms: a variable temperature spectroscopic investigation". Journal of Organometallic Chemistry. 688 (1–2): 49–55. doi:10.1016/j.jorganchem.2003.08.028.
  5. La(I), Pr(I), Tb(I), Tm(I), and Yb(I) have been observed in MB8 clusters; see Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng (2021). "Monovalent lanthanide(I) in borozene complexes". Nature Communications. 12 (1): 6467. doi:10.1038/s41467-021-26785-9. PMC   8578558 . PMID   34753931.
  6. Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN   0-8493-0464-4.
  7. 1 2 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  8. 1 2 3 4 5 6 7 8 9 10 11 12 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.
  9. 1 2 3 Hammond, C. R. (2000). "The Elements". Handbook of Chemistry and Physics (81st ed.). CRC press. ISBN   0-8493-0481-4.
  10. Jackson, M. (2000). "Magnetism of Rare Earth" (PDF). The IRM Quarterly. 10 (3): 1.
  11. Catherine E. Housecroft; Alan G. Sharpe (2008). "Chapter 25: The f-block metals: lanthanoids and actinoids". Inorganic Chemistry, 3rd Edition. Pearson. p. 864. ISBN   978-0-13-175553-6.
  12. "Chemical reactions of Thulium". Webelements. Retrieved 2009-06-06.
  13. Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. p. 934. ISBN   0-07-049439-8.
  14. Krebs, Robert E (2006). The History and Use of Our Earth's Chemical Elements: A Reference Guide. Greenwood Publishing. ISBN   978-0-313-33438-2.
  15. Eagleson, Mary (1994). Concise Encyclopedia Chemistry. Walter de Gruyter. p. 1105. ISBN   978-3-11-011451-5.
  16. Emeléus, H. J.; Sharpe, A. G. (1977). Advances in Inorganic Chemistry and Radiochemistry. Academic Press. ISBN   978-0-08-057869-9.
  17. 1 2 "Thulium". Retrieved 2023-03-10.
  18. Tarasov, O. B.; Gade, A.; Fukushima, K.; et al. (2024). "Observation of New Isotopes in the Fragmentation of 198Pt at FRIB". Physical Review Letters. 132 (072501). doi:10.1103/PhysRevLett.132.072501.
  19. 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.
  20. Belli, P.; Bernabei, R.; Danevich, F. A.; et al. (2019). "Experimental searches for rare alpha and beta decays". European Physical Journal A. 55 (8): 140–1–140–7. arXiv: 1908.11458 . Bibcode:2019EPJA...55..140B. doi:10.1140/epja/i2019-12823-2. ISSN   1434-601X. S2CID   201664098.
  21. 1 2 Sonzogni, Alejandro. "Untitled". National Nuclear Data Center . Retrieved 2013-02-20.
  22. 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.
  23. Eagleson, Mary (1994). Concise Encyclopedia Chemistry. Walter de Gruyter. p. 1061. ISBN   978-3-11-011451-5.
  24. Weeks, Mary Elvira (1956). The discovery of the elements (6th ed.). Easton, PA: Journal of Chemical Education.
  25. Weeks, Mary Elvira (1932). "The discovery of the elements: XVI. The rare earth elements". Journal of Chemical Education. 9 (10): 1751–1773. Bibcode:1932JChEd...9.1751W. doi:10.1021/ed009p1751.
  26. Marshall, James L. Marshall; Marshall, Virginia R. Marshall (2015). "Rediscovery of the elements: The Rare Earths–The Confusing Years" (PDF). The Hexagon: 72–77. Retrieved 30 December 2019.
  27. Piguet, Claude (2014). "Extricating erbium". Nature Chemistry. 6 (4): 370. Bibcode:2014NatCh...6..370P. doi: 10.1038/nchem.1908 . PMID   24651207.
  28. "Thulium". Royal Society of Chemistry. 2020. Retrieved 4 January 2020.
  29. James, Charles (1911). "Thulium I". Journal of the American Chemical Society. 33 (8): 1332–1344. doi:10.1021/ja02221a007.
  30. Hedrick, James B. "Rare-Earth Metals" (PDF). U.S. Geological Survey. Retrieved 2009-06-06.
  31. Castor, Stephen B. & Hedrick, James B. "Rare Earth Elements" (PDF). Retrieved 2009-06-06.
  32. Walker, Perrin & Tarn, William H. (2010). CRC Handbook of Metal Etchants. CRC Press. pp. 1241–. ISBN   978-1-4398-2253-1.
  33. Hudson Institute of Mineralogy (1993–2018). "". Retrieved 14 January 2018.
  34. ABUNDANCE OF ELEMENTS IN THE EARTH’S CRUST AND IN THE SEA, CRC Handbook of Chemistry and Physics, 97th edition (2016–2017), p. 14-17
  35. Koechner, Walter (2006). Solid-state laser engineering. Springer. p. 49. ISBN   0-387-29094-X.
  36. Duarte, Frank J. (2008). Tunable laser applications. CRC Press. p. 214. ISBN   978-1-4200-6009-6.
  37. 1 2 Gupta, C. K. & Krishnamurthy, Nagaiyar (2004). Extractive metallurgy of rare earths. CRC Press. p. 32. ISBN   0-415-33340-7.
  38. Raj, Baldev; Venkataraman, Balu (2004). Practical Radiography. Alpha Science Int'l. ISBN   978-1-84265-188-9.
  39. 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.
  40. Ayoub, Amal; Shani, Gad (2009). "Development of New Radioactive Seeds Tm-170 for Brachytherapy". In Dössel, Olaf; Schlegel, Wolfgang C. (eds.). World Congress on Medical Physics and Biomedical Engineering, September 7 - 12, 2009, Munich, Germany. IFMBE Proceedings. Vol. 25/1. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 1–4. doi:10.1007/978-3-642-03474-9_1. ISBN   978-3-642-03472-5 . Retrieved 2023-04-01.
  41. 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.
  42. Wardle, Brian (2009-11-06). Principles and Applications of Photochemistry. John Wiley & Sons. p. 75. ISBN   978-0-470-71013-5.
  43. Richards, Bryce S.; Howard, Ian A. (2023). "Luminescent solar concentrators for building integrated photovoltaics: opportunities and challenges". Energy & Environmental Science. 16 (8): 3214–3239. doi: 10.1039/D3EE00331K . ISSN   1754-5692.
  44. Ayres, D. C. (15 February 2022). Dictionary of environmentally important chemicals. Desmond Hellier (1st ed.). United States: CRC Press. p. 299. ISBN   978-1-315-14115-2. OCLC   1301431003.
  45. Jha, A. R. (2014). Rare Earth Materials : Properties and Applications. Boca Raton: CRC Press. p. 63. ISBN   978-1-4665-6403-9. OCLC   880825396.