Thulium

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Thulium is a chemical element with the element symbol Tm and atomic number 69 in the periodic table it is in the group of lanthanides and also making it one of the metals of the rare earths.

History

Thulium (named after Thule, the mythical island on the edge of the world) in 1879 by the Swedish chemist Per Teodor Cleve together with holmium in Erbia ( erbium oxide ) discovered (see research history of holmium ).

Occurrence

In nature, thulium occurs only in compounds. Thuliumhaltige minerals low concentration are:

  • Monazite (Ce, La, Th, Nd, Y) PO4 (Tm content < 0.01%)
  • Gadolinit (Tm content is about 0.25%)

Production and representation

After an extensive separation of the other Thuliumbegleiter the oxide is reduced to metallic lanthanum- thulium. Then the thulium is removed by sublimation.

Properties

The silver-gray rare earth metal is very soft, stretchable and malleable.

In dry air Thulium is quite stable in moist air it runs in gray. At higher temperatures it burns to the sesquioxide.

With water it reacts with evolution of hydrogen to the hydroxide. In mineral acids it dissolves with evolution of hydrogen.

In its compounds it is in the 3 oxidation state, the Tm3 ions form in water pastel bluish- green solutions.

Use

Thulium is the rarest of rare earth metal, but is still common in the earth's crust than gold or platinum. In addition to a minimum use in television sets ( for activation of the phosphors on the screen surface ), there are few commercial applications:

  • From nuclear reactors outsourced 170Tm serves as X-ray source ( gamma emitters in materials testing )
  • Thuliumdotiertes yttrium or lanthanum ( LaOBr ) is used as a scintillator in the X-ray intensifying screens or fluorescent screens in the X-ray technology
  • Thuliumdotiertes calcium sulfate is used as a detector in personal dosimeters to measure low doses
  • Thuliumkristalle can be used as the active medium in the diode-pumped solid state lasers ( wavelength of 2 microns ), with an overall efficiency of up to 10 % at a maximum of 60 W light power.
  • Thuliumdotiertes silica glass as the active medium in the fiber laser ( wavelength of 2 microns ) was operated with a differential efficiency of 53.2 % at an output of> 1000 W.

Safety

Thulium and Thuliumverbindungen are of low toxicity. Thuliumstäube are fire and explosion hazard.

Compounds

  • Thulium (III ) oxide Tm2O3
  • Thulium (III ) fluoride TmF3
  • Thulium (III ) chloride TmCl3
  • Thulium (III ) bromide TmBr3
  • Thulium (III ) iodide TmI3
  • Thulium (III ) sulphate Tm2 (SO4) 3 · 8 H2O
  • Thulium (III ) nitrate Tm ( NO3) 3 · 5H 2 O
Beryllium Fluorine Sodium Magnesium Aluminium Chlorine Argon Titanium Chromium Manganese Cobalt Nickel Zinc Germanium Arsenic Selenium Bromine Rubidium Zirconium Ruthenium Palladium Cadmium Indium Antimony Tellurium Barium Praseodymium Neodymium Samarium Europium Gadolinium Terbium Dysprosium Tantalum Tungsten Rhenium Osmium Iridium Lead Bismuth Polonium Astatine Francium Radium Actinium Neptunium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Dubnium Bohrium Darmstadtium Copernicium Group (periodic table) Period (periodic table) Block (periodic table) Period 6 element Color CAS registry number Covalent radius Half-life Decay energy Dangerous Substances Directive (67/548/EEC) Rare earth element Gadolinite Electronic visual display Thulium(III) oxide Thulium(III) chloride Digital Object Identifier Integrated Authority File
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