Effect of cationic order–disorder on the transport properties of LaBaCo2O6–δ and La0.5Ba0.5CoO3–δ perovskites

摘要: A-site cationic ordered LaBaCo2O6−δ and disordered La0.5Ba0.5CoO3−δ perovskite phases were obtained by solid state reaction. Their structural properties studied at room temperature 673 K, combining powder diffraction techniques, X-ray neutron with an independent determination of the oxygen content samples thermogravimetry. exhibits cubic symmetry cations randomly distributed, whereas shows tetragonal La3+ Ba2+ ions distributed in alternating layers. The data analyzed using Rietveld method different microstructural models. Bond valence Fourier methods used to determine bond distances neutron/electron density maps. a higher concentration vacancies than La0.5Ba0.5CoO3−δ, because O atom is weakly bonded LaO anisotropic atomic displacement distribution suggest two-dimensional O-migration path for three-dimensional La0.5Ba0.5CoO3−δ.The mechanism electrical conductivity via electron holes high mobilities (μLa0.5Ba0.5CoO3−δ = 2.49 cm2 V−1 s−1 μLaBaCo2O6−δ 1.48 cm2 V−1 s−1 temperature) low activation energy (EaLaBaCo2O6−δ  = 0.019 eV EaLa0.5Ba0.5CoO3−δ 0.030 eV). It has also been found that electronic ionic conductivities compared those are due dimensionality transport greater overlapping between Co 3d 2p orbitals.