Surface potential of BaTiO3 single crystal near the Curie temperature

A shift in the binding energies in Ba 3d and Ti 2p core-level spectra was observed when the electronic properties of nonprepolarized and prepolarized BaTiO3 surfaces were studied using x-ray photoelectron spectroscopy during heating and cooling near the Curie temperature (T-C). From a comparison of this shift for nonprepolarized and prepolarized crystals, different magnitudes and directions were noted. The differences are not connected with chemical shifts induced by any new chemical bonds. The shift in binding energy is considered to be a change of surface potential due to surface charging caused by the heating of the ferroelectric crystal through T-C.