A new class of thermionic electron emitters: Cesium tungsten bronzes, CsxWO3

A polycrystalline sample of Cs0.305WO3 was heated in the temperature range 390–630 °C in a UHV chamber. The values for the work function and thermionic constant are, respectively, 2.12±0.01 eV and 115 A/cm2 K2. The use of cesium tungsten bronzes as thermionic cathodes is limited to temperatures up to 630 °C, since at higher temperatures these materials deteriorate because of considerable loss of cesium. Tungsten bronzes, however, are suitable materials for systematic studies of the dependence of the work function on composition and structure.