Neutron structural characterization and transport properties of the oxidized and reduced LaCo0.5Ti0.5O3 perovskite oxide

6th Meeting of the Spanish Neutron Scattering Association

Martinez-Coronado, R.^1 ; Aguadero, A.^2 ; Alonso, J.A.^1 ; Perez-Coll, D.^3 ; Fernandez-Díaz, M.T.^4

Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco

E-28049, Spain^1

CIC Energigune, Albert Einstein 48, Alava

01510, Spain^2

Instituto de Cerámica y Vidrio-CSIC, Cantoblanco, Madrid

28049, Spain^3

Institut Laue Langevin, BP 156X, Grenoble

F-38042, France^4

关键词: Octahedral sites;    Oxygen stoichiometry;    Partial reduction;    Perovskite oxides;    Semiconductor like behaviors;    SOFC electrolyte;    Structural characterization;    Thermal expansion coefficients;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/549/1/012022/pdf
DOI  :  10.1088/1742-6596/549/1/012022

来源: IOP

【 摘 要 】

Polycrystalline oxygen-stoichiometric LaCo0.5Ti0.5O3perovskite oxide has been prepared by soft-chemistry procedures followed by annealing in air at 800°C. A new reduced LaCo0.5Ti0.5O3-δ specimen has been obtained by topotactical oxygen removal in an H2/N2 (5%/95%) flow at 600°C. The structural characterization has been conducted from neutron powder diffraction (NPD) data, very sensitive to the contrast between Co and Ti and the oxygen stoichiometry. Both perovskites (oxidized and reduced) crystallize in the orthorhombic Pbnm, space group. The partial reduction of Ti4+to Ti3+in the reduced phase is accompanied with the occurrence of oxygen vacancies, located at the axial octahedral sites, and it is expected to support the ionic conductivity, as usually observed in oxygen-defective perovskites. Thermogravimetric analysis (TGA) substantiates the oxygen stoichiometry and the stability range of the reduced sample. All the samples in study display a semiconductor-like behavior with values that not reach below to 0.5 Scm-1for all the phases. Moreover, the measured thermal expansion coefficients perfectly match with the values usually displayed by SOFC electrolytes.