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<p>(CeB<sub>6</sub>) are used as the coating of some high-current cathodes. Hexaborides show low work function, around 2.5 <a href="page.php?w=electronvolt">eV</a>. They are also resistant to poisoning. Cerium boride cathodes show lower evaporation rate at 1700 <a href="page.php?w=Kelvin">K</a> than lanthanum boride, but it becomes equal at 1850 K and higher. Cerium boride cathodes have one and a half times the lifetime of lanthanum boride, due to its higher resistance to carbon contamination. Boride cathodes are about ten times as "bright" as the</p><p>
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