Scandia-doped tungsten bodies for Sc-type cathodes

We systematically investigated scandium oxide-doped (and with small amount of rhenium-doped) tungsten bodies for Scandate-type cathodes. Homogeneous microstructure and uniform distribution of scandia were found in these bodies. Sub-micron granular porous bodies with greatly uniformly dispersed scandia are obtained by sintering Sc2O3 and Re doped tungsten powder. Such bodies are thought to be beneficial for emission uniformity. For Scandate-type cathodes with such bodies, a slight decrease of scandia was observed by “in situ” AES analysis after ion sputtering, but it recovers completely on reheating. It is assumed that film-like Sc2O3 coating over tungsten grains but leaving porous areas for diffusion of barium to the surface leads to good emission properties and high resistance to ion bombardment. Reprocucibility has been proved for the body manufactering process. This offers the possibility of improving the performance of these cathodes in applications such as CRT’s.