Terbium

From Free net encyclopedia

Template:Elementbox header Template:Elementbox series Template:Elementbox periodblock Template:Elementbox appearance img Template:Elementbox atomicmass gpm Template:Elementbox econfig Template:Elementbox epershell Template:Elementbox section physicalprop Template:Elementbox phase Template:Elementbox density gpcm3nrt Template:Elementbox densityliq gpcm3mp Template:Elementbox meltingpoint Template:Elementbox boilingpoint Template:Elementbox heatfusion kjpmol Template:Elementbox heatvaporiz kjpmol Template:Elementbox heatcapacity jpmolkat25 Template:Elementbox vaporpressure katpa Template:Elementbox section atomicprop Template:Elementbox crystalstruct Template:Elementbox oxistates Template:Elementbox electroneg pauling Template:Elementbox ionizationenergies4 Template:Elementbox atomicradius pm Template:Elementbox atomicradiuscalc pm Template:Elementbox section miscellaneous Template:Elementbox magnetic Template:Elementbox eresist ohmm Template:Elementbox thermalcond wpmkat300k Template:Elementbox thermalexpansion umpmk Template:Elementbox speedofsound rodmpsat20 Template:Elementbox youngsmodulus gpa Template:Elementbox shearmodulus gpa Template:Elementbox bulkmodulus gpa Template:Elementbox poissonratio Template:Elementbox vickershardness mpa Template:Elementbox brinellhardness mpa Template:Elementbox cas number Template:Elementbox isotopes begin Template:Elementbox isotopes decay Template:Elementbox isotopes decay2 Template:Elementbox isotopes stable Template:Elementbox isotopes end Template:Elementbox footer

Terbium is a chemical element in the periodic table that has the symbol Tb and atomic number 65.

Contents 1 Notable characteristics 2 Applications 3 History 4 Occurrence 5 Compounds 6 Isotopes 7 Precautions 8 References 9 External links

Notable characteristics

Terbium is a silvery-white rare earth metal that is malleable, ductile and soft enough to be cut with a knife. It is reasonably stable in air, and two crystal allotropes exist, with a transformation temperature of 1289 °C.

Applications

Terbium is used to dope calcium fluoride, calcium tungstate and strontium molybdate, materials that are used in solid-state devices, and as a crystal stabilizer of fuel cells which operate at elevated temperatures, together with ZrO₂. Terbium is also used in alloys and in the production of electronic devices, its oxide is used in green phosphors in fluorescent lamps and color TV tubes. Sodium terbium borate is used in solid state devices.

History

Terbium was discovered in 1843 by Swedish chemist Carl Gustaf Mosander, who detected it as an impurity in Yttrium-oxide, Y₂O₃, and named after the village Ytterby in Sweden. It was not isolated in pure form until the recent advent of ion exchange techniques.

Occurrence

Terbium is never found in nature as the free element, but it is contained in many minerals, including cerite, gadolinite, monazite ((Ce,LaTh,Nd,Y)PO₄, which contains up to 0.03% of Terbium), xenotime (YPO₄) and euxenite ((Y,Ca,Er,La,Ce,U,Th)(Nb,Ta,Ti)₂O₆, which contains 1% or more of Terbium).

Compounds

Terbium compounds include:

• Fluorides
  • TbF₃
  • TbF₄
• Chlorides
  • TbCl₃
• Bromides
  • TbBr₃
• Iodides
  • TbI₃
• Oxides
  • Tb₂O₃
  • Tb₄O₇
• Sulfides
  • Tb₂S₃
• Nitrides
  • TbN

See also terbium compounds.

Isotopes

Naturally occurring Terbium is composed of 1 stable isotope, 159-Tb. 33 radioisotopes have been characterized, with the most stable being 158-Tb with a half-life of 180 years, 157-Tb with a half-life of 71 years, and 160-Tb with a half-life of 72.3 days. All of the remaining radioactive isotopes have half-lifes that are less than 6.907 days, and the majority of these have half lifes that are less than 24 seconds. This element also has 18 meta states, with the most stable being 156m1-Tb (t_½ 24.4 hours), 154m2-Tb (t_½ 22.7 hours) and 154m1-Tb (t_½ 9.4 hours).

The primary decay mode before the most abundant stable isotope, 159-Tb, is electron capture, and the primary mode after is beta minus decay. The primary decay products before 159-Tb are element Gd (Gadolinium) isotopes, and the primary products after are element Dy (Dysprosium) isotopes.

Precautions

As with the other lanthanides, terbium compounds are of low to moderate toxicity, although their toxicity has not been investigated in detail. Terbium has no known biological role.

References

• Los Alamos National Laboratory – Terbium

External links

Template:Commons Template:Wiktionary

• WebElements.com – Terbium
• It's Elemental – Terbiumca:Terbi

cs:Terbium de:Terbium et:Terbium es:Terbio eo:Terbio fr:Terbium ko:터븀 io:Terbio it:Terbio he:טרביום lt:Terbis hu:Terbium nl:Terbium ja:テルビウム no:Terbium nn:Terbium pl:Terb pt:Térbio ru:Тербий sl:Terbij sr:Тербијум fi:Terbium sv:Terbium th:เทอร์เบียม uk:Тербій zh:铽