Work function changes in Hf/W(011) and Hf/W(001) adsorption systems

Work function changes for the Hf/W(011) and Hf/W(001) adsorption systems were investigated by the diode method. Hf dissolves at the W(001) substrate in the temperature range 600–1700 K. Up to 1700 K work function changes vs. annealing temperature have opposite courses for each of the adsorption systems. Work function increases for the Hf/W(011) and decreases for the Hf/W(001). The largest work function reduction measured for the Hf/W(001) amounts to 1.80 eV. The work function changes have been correlated with low energy electron diffraction patterns observed for the corresponding amounts of deposited adsorbate. Conclusions were drawn concerning the possibility of surface alloy formation in the Hf/W(001) system as a precursor for the intermetallic Laves phase HfW2.