Orientation dependent work function of in situ annealed strontium titanate

We have used energy filtered x-ray photoelectron emission microscopy (XPEEM) and synchrotron radiation to measure the grain orientation dependence of the work function of a sintered niobium doped strontium titanate ceramic. A significant spread in work function values is found. Grain orientation and surface reducing/oxidizing conditions are the main factors in determining the work function. Energy filtered XPEEM looks ideally suited for analysis of other technologically interesting polycrystalline samples.