X-RAY PHOTOEMISSION SPECTROSCOPY (XPS) ANALYSIS ON PLATINUM DOPED STANNIC OXIDE CERAMIC

Abstract

Pt-SnO₂ ceramics were fabricated by the dry pressing method and sintered at 1000 °C.  The XPS spectrum showed the Sn 4d, Sn 4p, Sn 4s, C 1s, Sn 3d_5/2, Sn 3d_3/2, O 1s, Sn 3p_1/2 and Sn 3s peaks.  The high resolution scan of revealed that the O 1s has a binding energy of 530.2 eV which indicates that there were oxygen vacancies in the doped material.  The FWHM XPS spectrum was broader than the pure SnO₂, which shows that there is a greater range of chemical environments and hence binding energies.  The asymmetry in the O 1s also shows that adsorbed oxygen exists on the surface of the sample in ambient atmosphere. The Sn 3d_5/2 peak was symmetric and has a small FWHM indicating that the compound has one component only.  The atomic ratio of oxygen and tin (ratio of O 1s and Sn 3d_5/2) is ~ 1.30:1, a deviation of stoichiometry which was caused by oxygen deficiency on the surface region.  The binding energies of both the Sn 3d_5/2 and Sn 3d_3/2 shifted by 0.01 eV with respect to the pure SnO₂ XPS spectrum sintered at the same temperature (1000 °C) and this is an indication that the chemical environment was changing due to the incorporation of Pt in SnO₂.  The Pt(2) which shows from the XPS spectrum was  probably an oxide layer on the Pt metal or possibly dissolved in the SnO₂.  The XPS analysis also showed that the Pt 4 f looks like mainly Pt(0) or Pt metal.