Effects of activation time and temperature on electrical conductivity of novel cermet oxide cathodes for CRT applications

A new generation of oxide cermet cathodes was activated at 850 and 1150 deg. C for various lengths of time. The grain boundaries in the oxide layer increased with activation time for the cathodes activated at 850 deg. C. The growth of interfacial Al2O3 and WO3 layers and the concentration of free Ba on the surface for activation at 850 deg. C for a period less than 3 h were found to be different from the ones observed for longer than 3 h. This type of behaviour was not observed for the cathodes at 1150 deg. C. The conductivity measured at low temperatures on a cathode activated at 850 deg. C was much higher for long activation than for a short period of activation. Activation at 1150 deg. C for a period longer than 2 h produced a disruptive effect of low conductivity and high activation energy