Heat-field treatment of tips made of tungsten-hafnium alloy

The combined effect of a high electric field and a high temperature on the morphology of W-Hf field-emission tips is studied. It is shown that, while the tip reconfiguration stages for this alloy are basically the same as for pure tungsten, they have a number of specific features due to the surface segregation of hafnium. The heat-field treatment of these emitters narrows the solid angle of emission significantly, improves the emissivity of the tips, and is accompanied by the high-temperature evaporation primarily of Hf atoms.