Temperature Dependence of the Work Function of Metals (Mo,Ni)

The temperature coefficient of the work function (TCWF) of polycrystalline Mo and Ni has been measured in the temperature ranges 600-1100°K and 475-1025°K, respectively, using the electron beam method (EBM). Special precautions have been taken in order to avoid systematic errors due to the effect of residual gases, of stray magnetic fields, of incorrect temperature measurement, of cathode temperature variations, etc. During determinations made upon Ni surfaces, the terrestrial magnetic field has been compensated. Random error sources have been like-wise reduced as much as possible. The main results obtained on surfaces outgassed for many thousands of hours at pressures of 1-3×${10}^{-9\mathrm{}}$ torr are ${〈〉\left(\left(\frac{d{\Psi }_{\mathrm{Mo}}}{\mathrm{dT}}\right)\right)}_{\mathrm{av}}=(7.84\mathrm{}\pm 0.07)\times {10}^{-5\mathrm{}}\mathrm{ev}/°\mathrm{K},$ ${〈〉\left({\left(\frac{d{\Psi }_{\mathrm{Ni}}}{\mathrm{dT}}\right)}_{T>\mathrm{}{\theta }_{\mathrm{Curie}}}\right)}_{\mathrm{av}}=(-3.12\mathrm{}\pm 0.05)\times {10}^{-5\mathrm{}}\mathrm{ev}/°\mathrm{K}.$