Oxygen nonstoichiometry, defect structure and oxygen diffusion in the double perovskite GdBaCo2O6−δ

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 43; no. 42; pp. 15937 - 15943
• Main Authors: Tsvetkov, D. S, Ananjev, M. V, Eremin, V. A, Zuev, A. Yu, Kurumchin, E. Kh
• Format: Journal Article
• Language: English
• Published: England 14.11.2014
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c4dt01486c

Oxygen nonstoichiometry of GdBaCo 2 O 6− δ was studied by means of the thermogravimetric technique in the temperature range 600-1000 °C. The defect structure model based on the simple cubic perovskite GdCoO 3− δ was shown to be valid for GdBaCo 2 O 6− δ up to temperatures as low as 600 °C. Two independent methods, namely dc-polarization with the YSZ microelectrode and 18 O-isotope exchange with gas phase analysis, were used to determine the oxygen self-diffusion coefficient in the double perovskite GdBaCo 2 O 6− δ . All measurements were carried out using ceramic samples identically prepared from the same single phase powder of GdBaCo 2 O 6− δ . The experimental data on oxygen nonstoichiometry of GdBaCo 2 O 6− δ allowed a precise calculation of the oxygen interphase exchange rate and the oxygen tracer diffusion coefficient on the basis of the isotope exchange measurements. The values of the oxygen self-diffusion coefficient measured by the dc-polarization technique were found to be in very good agreement with the ones of the oxygen tracer diffusion coefficient. The values of the oxygen self-diffusion coefficient measured by the dc-polarization technique completely coincide with those of the oxygen tracer diffusion coefficient.