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Nanocrystalline CeO2 samples were prepared via precipitation from aqueous cerium(IV) sulfate solution under a controlled pH. After being subjected to calcination at various temperatures to yield different particle sizes, the local structure around Ce atom was investigated by using EXAFS spectroscopy at Ce K-edge. The first shell Ce&z.sbnd;O distance was found to be slightly shorter with small CeO2 particles, indicating a contraction of the lattice. There exists a significant growth in coordination number of the second cell Ce&z.sbnd;Ce when the particle size became larger. In terms of Debye–Waller factor (σ2), the first three coordination shells showed a consistent trend, i.e. the degree of disorder increases with reduced particle size. Moreover, σ2 of the second shell was found to be smaller than that of the first shell for all samples. [ABSTRACT FROM AUTHOR]

The electronic and atomic structures of quasi-one-dimensional blue bronze K0.3MoO3 were investigated by polarization-dependent O K-edge x-ray absorption near-edge structure (XANES) and Mo K-edge extended x-ray absorption fine structure (EXAFS) measurements at various temperature and applied voltages. The O K-edge XANES spectra suggest that the number of unoccupied O 2p–Mo 4d hybridized states increases and decreases with temperature, respectively, below and above a critical temperature of 180 K. The along b-axis electric current measurements show a threshold applied voltage, beyond which the current increases rapidly. The Mo K-edge EXAFS measurements show that the Mo–O bond lengths are insensitive to the temperature even beyond 180 K. [ABSTRACT FROM AUTHOR]

The electronic and atomic structures of quasi-one-dimensional blue bronze K0.3MoO3 were investigated by polarization-dependent O K-edge x-ray absorption near-edge structure (XANES) and Mo K-edge extended x-ray absorption fine structure (EXAFS) measurements at various temperature and applied voltages. The O K-edge XANES spectra suggest that the number of unoccupied O 2p–Mo 4d hybridized states increases and decreases with temperature, respectively, below and above a critical temperature of 180 K. The along b-axis electric current measurements show a threshold applied voltage, beyond which the current increases rapidly. The Mo K-edge EXAFS measurements show that the Mo–O bond lengths are insensitive to the temperature even beyond 180 K. [ABSTRACT FROM AUTHOR]