Local structure distortion evaluation of Ba0.5Sr0.5Fe1-xCuxZr0.05O3-δ facing physical properties alteration
SUASMORO S. 1, FITRIANA F. 2, KLUSYUBUN W. 3, KATO M. 4
1 Institut Teknologi 'Sepuluh Nopember' Surabaya, Surabaya, Indonesia; 2 Dept. of Physics, Universitas Negri Surabaya, Surabaya 60231, Indonesia, Surabaya, Indonesia; 3 Synchroton Light Research Institute (Public Organisation), 111 University Avenue, Muang, Nakhon Ratchasima 30000, Thailand, Nakhon Ratchasima, Thailand; 4 Department of Applied Physics, Tohoku University, 6-6-05, Aoba, Aramaki, Aoba-Ku, Sendai 980-8579, Japan, Sendai, Japan
The composition Ba0.5Sr0.5Fe1-xCuxZr0.05O3-δ (BSFCZ, x=0-0.15) was successfully synthesized by the sol-gel self-combustion method using starting materials of the associated metals and citric acid as fuel combustion. Their structure, local structure, electric and magnetic properties are investigated. The XRD measurements revealed that all the oxides exhibit a cubic structure, with space group Pm3m and lattice parameter increases with x, a = 3.9230 Å for x=0 up to a = 3.9474 Å for x = 0.15. The X-ray absorption data are discussed in detail concerning Fe, and Cu K-edge shift was related to Fe and Cu’s oxidation state (OS). The OS of Fe was 3.49 for the BSFZ sample and became 3.6 and 3.4 for x=0.05 and x=0.15, respectively; correspondently, the OS of Cu was 2.12 and 2.28. The local lattice distortion was evaluated through EXAFS data. The Fourier transforms simulation of scattering contributions from the first neighbor oxygen shell was used to assess the Fe-O and Cu-O bond length. The substitution of iron by copper and zirconium leads to a corresponding increase of the iron valence state and, thus, the formation of the Jahn-Teller effect Fe4+ ion. The nonstoichiometric δ-value (3-δ) measured by iodometric titration is consistent with X-ray absorption data leading to oxygen vacancy Vo.. defect. The electrical conductivity increases significantly after substituting Fe and Zr with Cu up to 60 Scm-1, a potential used as a SOFC cathode. Furthermore, the magnetic properties show that all the oxides exhibit paramagnetic.