© The Royal Society of Chemistry 2015. Stoichiometry and oxygen diffusion properties of La2-xSrxNiO4±δ with x = 0.2, 0.4, 0.6, and 0.8 prepared via a sol-gel method were investigated in this study. Iodometric titration and thermogravimetric analysis were used to determine the oxygen non-stoichiometry. Over the entire compositional range, the samples exhibit oxygen hyperstoichiometry with the minimum value δ = 0.14 at x = 0.4. Mixed effects of reduction of oxygen excess and increasing valence of Ni were found to serve as charge compensation mechanisms; the former dominated at a low level of substitution, x < 0.4, while the latter dominated at higher levels of Sr (0.4 < x < 0.8). The highest oxygen diffusion coefficient was found for the minimum amount of Sr substitution, x = 0.2, continuously decreasing with x until x = 0.6. An unusual increase in D∗ was observed when the Sr content increased up to x = 0.8.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was partially funded by the postgraduate education and research programs in Petroleum and Petrochemical Technology (PPT Consortium), Rachadapisake Sompote fund, Chulalongkorn University, the Development and Promotion of Science and Technology, Thailand project (DPST), National Metal and Materials Technology Center (MTEC), Thailand (P-0030259), a Marie Curie Intra European Fellowship within the seventh European Community Framework Programme (PIEFGA- 2009-252711) and from King Abdullah University of Science & Technology, Saudi Arabia (for M. B). The authors would like to thank Dr Sumittra Charojrochkul from MTEC, Thailand for useful discussion, and staff at the Department of Materials, Imperial College London for their support for the work performed at the Imperial College, London.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.