Electrical conductivity and lattice defects in nanocrystalline cerium oxide thin films

The results of the electrical conductivity and Raman scattering measurement s of CeO2 thin films obtained by a polymeric precursor spin-coating techniq ue are presented. The electrical conductivity has been studied as a functio n of temperature and oxygen activity and correlated with the grain size. Wh en compared with microcrystalline samples, nanocrystalline materials show e nhanced electronic conductivity. The transition from extrinsic to intrinsic type of conductivity has been observed as the grain size decreases to < 10 0 nm, which appears to be related to a decrease in the enthalpy of oxygen v acancy formation in CeO2. Raman spectroscopy has been used to analyze the c rystalline quality as a function of grain size. A direct comparison has bee n made between the defect concentration calculated from coherence length an d nonstoichiometry determined from electrical measurements.