|Stockholm—Carl Gustaf Mosander elements|
Mosander found two impurities, both oxides, in his oxide of yttrium—one rosy and the other yellow. Having named yttrium from the first syllable of the village where it was found, Ytterby, he named the second after the second syllable, terb. And guess what he called the third one. Mosander named the rose oxide terbia, and the yellow oxide erbia, but Nils Johan Berlin couldn’t find the yellow oxide, so he named terbia erbia.
Atomic number 65
Terbium phosphors give the green color in TV tubes, LCD screens, and “trichromatic” lighting. Shine an ultraviolet light on a euro banknote to cause green fluorescence from terbium. Terfenol-D, an alloy of terbium, dysprosium, and iron, expands and contracts in a magnetic field. Terbium, neodymium, and dysprosium alloys make strong magnets for electric motors and wind turbines. Terbium is used as a dopant in solid state devices and as a crystal stabilizer of high-temperature fuel cells.
Tweedledum and Tweedledee
Terbium and erbium walked into a bar, where they met yttrium, and ordered oxygen-potassium cocktails. They asked for the senior discount. The bartender said OK, OK, but not for your friend yttrium; we know he’s only 39.