Tungsten has a small electron work function (4.5eV), and a strong electron emission capability at high temperatures. High hardness, high temperature performance, low resistivity, small expansion coefficient. The addition of rare earth oxides（REO） to Tungsten can excite the electronic work function of Tungsten, has better electrode arcing performance, the stability of the arc column is higher, and the burn loss rate of the electrode is lower.

Common rare earth additives include cerium oxide, lanthanum oxide, zirconium oxide, yttrium oxide and thorium oxide.