Naturally occurring terbium (65Tb) is composed of 1 stable isotope, 159Tb. Thirty-six radioisotopes have been characterized, with the most stable being 158Tb with a half-life of 180 years, 157Tb with a half-life of 71 years, and 160Tb with a half-life of 72.3 days. All of the remaining radioactive isotopes have half-lives that are less than 6.907 days, and the majority of these have half-lives that are less than 24 seconds. This element also has 27 meta states, with the most stable being 156m1Tb (t1/2 24.4 hours), 154m2Tb (t1/2 22.7 hours) and 154m1Tb (t1/2 9.4 hours).
The primary decay mode before the most abundant stable isotope, 159Tb, is electron capture, and the primary mode behind is beta decay. The primary decay products before 159Tb are element Gd (gadolinium) isotopes, and the primary products behind are element Dy (dysprosium) isotopes.
|Main isotopes of terbium (65Tb)|
|Standard atomic weight Ar, standard(Tb)|
isotopic mass (u)
|range of natural|
|138Tb||65||73||137.95316(43)#||800# ms [>200 ns]||β+||138Gd|
|140Tb||65||75||139.94581(86)||2.4(2) s||β+ (99.74%)||140Gd||5|
|β+, p (.26%)||139Eu|
|141mTb||0(200)# keV||7.9(6) s||β+||141Gd||11/2−#|
|142m1Tb||280.2(10) keV||303(17) ms||IT (99.5%)||142Tb||(5−)|
|142m2Tb||621.4(11) keV||15(4) µs|
|143mTb||0(100)# keV||<21 s||β+||143Gd||5/2+#|
|β+, p (rare)||143Eu|
|144m1Tb||396.9(5) keV||4.25(15) s||IT (66%)||144Tb||(6−)|
|β+, p (<1%)||143Eu|
|144m2Tb||476.2(5) keV||2.8(3) µs||(8−)|
|144m3Tb||517.1(5) keV||670(60) ns||(9+)|
|144m4Tb||544.5(6) keV||<300 ns||(10+)|
|145mTb||0(100)# keV||30.9(7) s||β+||145Gd||(11/2−)|
|146m1Tb||150(100)# keV||24.1(5) s||β+||146Gd||5−|
|146m2Tb||930(100)# keV||1.18(2) ms||(10+)|
|147mTb||50.6(9) keV||1.87(5) min||β+||147Gd||(11/2)−|
|148m1Tb||90.1(3) keV||2.20(5) min||β+||148Gd||(9)+|
|148m2Tb||8618.6(10) keV||1.310(7) µs||(27+)|
|149Tb||65||84||148.923246(5)||4.118(25) h||β+ (83.3%)||149Gd||1/2+|
|149mTb||35.78(13) keV||4.16(4) min||β+ (99.97%)||149Gd||11/2−|
|150Tb||65||85||149.923660(8)||3.48(16) h||β+ (99.95%)||150Gd||(2−)|
|150mTb||457(29) keV||5.8(2) min||β+||150Gd||9+|
|151Tb||65||86||150.923103(5)||17.609(1) h||β+ (99.99%)||151Gd||1/2(+)|
|151mTb||99.54(6) keV||25(3) s||IT (93.8%)||151Tb||(11/2−)|
|152m1Tb||342.15(16) keV||0.96 µs||5−|
|152m2Tb||501.74(19) keV||4.2(1) min||IT (78.8%)||152Tb||8+|
|153mTb||163.175(5) keV||186(4) µs||11/2−|
|154Tb||65||89||153.92468(5)||21.5(4) h||β+ (99.9%)||154Gd||0(+#)|
|154m1Tb||12(7) keV||9.4(4) h||β+ (78.2%)||154Gd||3−|
|154m2Tb||200(150)# keV||22.7(5) h||7−|
|154m3Tb||0+Z keV||513(42) ns|
|156m1Tb||54(3) keV||24.4(10) h||IT||156Tb||(7−)|
|156m2Tb||88.4(2) keV||5.3(2) h||(0+)|
|158Tb||65||93||157.9254131(28)||180(11) y||β+ (83.4%)||158Gd||3−|
|158m1Tb||110.3(12) keV||10.70(17) s||IT (99.39%)||158Tb||0−|
|158m2Tb||388.37(15) keV||0.40(4) ms||7−|
|161Tb[n 3]||65||96||160.9275699(28)||6.906(19) d||β−||161Dy||3/2+|
Gadolinium is a chemical element with symbol Gd and atomic number 64. Gadolinium is silvery-white metal when oxidation is removed. It is only slightly malleable and is a ductile rare-earth metal. Gadolinium reacts with atmospheric oxygen or moisture slowly to form a black coating. Gadolinium below its Curie point of 20 °C (68 °F) is ferromagnetic, with an attraction to a magnetic field higher than that of Nickel. Above this temperature it is the most paramagnetic element. It is found in nature only in an oxidized form. When separated, it usually has impurities of the other rare-earths because of their similar chemical properties.
Gadolinium was discovered in 1880 by Jean Charles de Marignac, who detected its oxide by using spectroscopy. It is named after the mineral gadolinite, one of the minerals in which gadolinium is found, itself named for the chemist Johan Gadolin. Pure gadolinium was first isolated by the chemist Paul Emile Lecoq de Boisbaudran around 1886.
Gadolinium possesses unusual metallurgical properties, to the extent that as little as 1% of gadolinium can significantly improve the workability and resistance to oxidation at high temperatures of iron, chromium, and related metals. Gadolinium as a metal or a salt absorbs neutrons and is, therefore, used sometimes for shielding in neutron radiography and in nuclear reactors.
Like most of the rare earths, gadolinium forms trivalent ions with fluorescent properties, and salts of gadolinium(III) are used as phosphors in various applications.
The kinds of gadolinium(III) ions occurring in water-soluble salts are toxic to mammals. However, chelated gadolinium(III) compounds are far less toxic because they carry gadolinium(III) through the kidneys and out of the body before the free ion can be released into the tissues. Because of its paramagnetic properties, solutions of chelated organic gadolinium complexes are used as intravenously administered gadolinium-based MRI contrast agents in medical magnetic resonance imaging.Terbium
Terbium is a chemical element with symbol Tb and atomic number 65. It is a silvery-white, rare earth metal that is malleable, ductile, and soft enough to be cut with a knife. 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.
Swedish chemist Carl Gustaf Mosander discovered terbium as a chemical element in 1843. He detected it as an impurity in yttrium oxide, Y2O3. Yttrium and terbium are named after the village of Ytterby in Sweden. Terbium was not isolated in pure form until the advent of ion exchange techniques.
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. As a component of Terfenol-D (an alloy that expands and contracts when exposed to magnetic fields more than any other alloy), terbium is of use in actuators, in naval sonar systems and in sensors.
Most of the world's terbium supply is used in green phosphors. Terbium oxide is in fluorescent lamps and television and monitor cathode ray tubes (CRTs). Terbium green phosphors are combined with divalent europium blue phosphors and trivalent europium red phosphors to provide trichromatic lighting technology, a high-efficiency white light used for standard illumination in indoor lighting.