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Facts About Terbium

Atomic Number: 65
Atomic Symbol: Tb
Atomic Weight: 158.92535

Melting Point: 2,473 F (1,356 C)
Boiling Point: 5,846 F (3,230 C)

Word origin: Terbium was named for the village of Ytterby, Sweden (as was yttrium, erbium and ytterbium).

Discovery: Swedish chemist Carl Gustaf Mosander separated the mineral gadolinite into three materials, which he called yttria, erbia and terbia, in 1843. From two of these substances, he discovered erbium and terbium.

Properties of terbium

Terbium is a member of the lanthanide or rare earth group of elements. [See Periodic Table of the Elements]

The silver-gray metal, which is relatively stable in air, is malleable and can be cut with a knife. Two crystal modifications, with a transformation temperature of 2,352 F (1,289 C), are known.

The oxide is a dark maroon or chocolate color, and 21 isotopes with atomic masses ranging from 145 to 165 are recognized. The oxide form is chocolate or dark maroon.

Terbium
Three grams of pure terbium, about 1 cm.
Credit: Images of elements

There is scant information on the toxicity of terbium, so it must be handled carefully.

Sources of terbium

Along with other rare earth elements, terbium can be found in minerals, including cerite and gadolinite. The element can be extracted from monazite, in which it is present to the extent of 0.03 percent; from euxenite, a complex oxide containing 1 percent or more of terbia; and xenotime.

Recent advances ion-exchange techniques for separating the rare earth elements have enabled the isolation of terbium. One method for producing the rare earth metal is by reducing the anhydrous chloride or fluoride with calcium, although other methods of isolation are available. Vacuum remelting can remove calcium and tantalum impurities.

Uses of terbium

While there are not many commercial uses for terbium, sodium terbium borate is used in solid-state devices. When combined with zirconium dioxide (ZrO2), it can act as a crystal stabilizer of elevated-temperature fuel cells.

(Source: Los Alamos National Laboratory)

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