J C Waerenborgh et al 2001 J. Phys.: Condens. Matter 13 8171 doi:10.1088/0953-8984/13/35/322
J C Waerenborgh1,5, F M Figueiredo2,3, J R Frade2, M T Colomer4 and J R Jurado4
Show affiliationsCaFexTi1-xO3-y (0.05≤x≤0.60) and SrFexTi1-xO3-y (0.20≤x≤0.60) perovskites were prepared by solid state reaction and subjected to different heat treatments in different atmospheres. Mössbauer spectroscopy of the CaFexTi1-xO3-y could detect Fe4+ in all the samples, even in those heated at 1000 °C in Ar atmosphere for 10 hours. Fe3+ coordinated by six, five and four anions were also identified and the estimated hyperfine parameters were consistent with those previously reported for the CaFexTi1-xO3-x/2 oxides where all the Fe cations were present as Fe3+. The Fe4+/Fe3+ ratios estimated from Mössbauer data are in agreement with coulometric titration data. The absence of tetracoordinated Fe3+ in SrFexTi1-xO3-y suggests that in contrast to CaFexTi1-xO3-y no ordering of anion vacancies takes place even for x = 0.60 and explains the differences in the Fe concentration dependence of the electric transport properties of these materials.
76.80.+y Mössbauer effect; other γ-ray spectroscopy
Issue 35 (3 September 2001)
Received 18 April 2001
Published 16 August 2001
J C Waerenborgh et al 2001 J. Phys.: Condens. Matter 13 8171
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