Abstract
We have measured the ac conductivity and dielectric spectra for La2-xYxMo2O9 (0.05 ≤ x ≤ 0.20) in wide temperature and frequency ranges. We have obtained the mean square displacement and the spatial extent of nonrandom sub-diffusive regions for oxygen ions by analyzing the ac conductivity and dielectric spectra respectively. The structure of the samples has been studied using X-ray photoelectron spectra, X-ray and electron diffraction. It is observed that the composition dependence of these characteristic lengths is correlated with the distance between oxygen ions obtained from structural studies.
Highlights
Oxide ion conductors, such as yttria stabilized zirconia, are of considerable interest due to their potential applications in solid oxide fuel cells, oxygen sensors and oxygen separation membranes.[1,2,3] Recently, a new oxide ion conductor based on La2Mo2O9 has been discovered.[4]
It has been reported that β−La2Mo2O9 exhibits higher oxide ion conductivity at 973 K than that of the yttria stabilized zirconia at the same temperature
X-ray diffraction and synchrotron studies of β−La2Mo2O9 show that O1 site is fully occupied, while O2 and O3 sites are partially (78%) occupied, resulting in a high concentration of intrinsic oxygen vacancy for β−La2Mo2O9.7 On the other hand, molecular dynamics simulation of β−La2Mo2O9 has confirmed that in the nanoscopic range, the time average cubic structure associated with La and Mo polyhedral units is energetically favorable for oxide ion conduction at high temperatures.[10]
Summary
Oxide ion conductors, such as yttria stabilized zirconia, are of considerable interest due to their potential applications in solid oxide fuel cells, oxygen sensors and oxygen separation membranes.[1,2,3] Recently, a new oxide ion conductor based on La2Mo2O9 has been discovered.[4]. We have established a correlation of the results of structural studies obtained using. X-ray photoelectron spectra, X-ray and electron diffractions for Y substituted La2Mo2O9 (0.05 ≤ x ≤ 0.20) conductors with the results of oxygen ion dynamics obtained from impedance spectra and linear response theory
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