EELS and photoemission study of antimony-doped Cd2SnO4 ceramics

Abstract

Ceramic samples of antimony-doped dicadmium stannate Cd₂Sn_{1 –x}Sb_xO₄ prepared in air by standard solid-state synthetic procedures have been studied over the range 0 ⩽x⩽ 0.05 by electron energy loss spectroscopy (EELS) and ultraviolet and X-ray photoemission spectroscopy (UPS and XPS). The maximum plasmon energy for doped samples is about 0.6 eV, corresponding to a carrier concentration of 2.4 × 10²⁰ cm^–3. The carrier concentration probed by EELS always exceeds the nominal doping level by about 4.0 × 10¹⁹ cm^–3. UPS shows a well defined conduction band feature, whose intensity increases with antimony concentration. The shape of the conduction band conforms tolerably well to a parabolic free-electron-like profile. The width of the conduction band of highly doped samples is in good agreement with that expected from a free electron model. A pronounced segregation of Sb to surface is evident from XPS and is discussed in detail.