abstract
A study of the structure of Fe-1V CaTi0.4Fe0.6O3-delta is presented and compared to data on the Fe-III counterparts. The powder XRD pattern was dominated by a simple cubic perovskite unit cell;, however, some small peaks indicated an orthorhombic distortion. All peaks could be indexed using a space group analogous to the Fe-III phase Ca3TiFe2O8. From HRTEM the strong cubic peaks are well explained by the Superposition of three equivalent and mutually perpendicular orthorhombic unit cells. TEM analysis further revealed a microdomain structure consisting of disordered intergrowths of CaTiO3- and Ca3TiFe2O8-like phases. Mossbauer spectra show that ca. 4% of the Fe cations are in the 4+ oxidation state. Results suggest that the Fe 4+ cations are associated with octahedral coordination and hence are associated with the CaTiO3-like regions, transition regions between the CaTiO3- and Ca3TiFe2O8 intergrown phases and the domain boundaries. Structural models for the intergrowths are proposed based on HRTEM image simulations. (C) 2004 Elsevier Inc. All rights reserved.
keywords
CALCIUM LANTHANUM FERRITES; OXYGEN VACANCIES; CAFE(X)TI1-XO3-X/2 PEROVSKITES; MOSSBAUER-SPECTROSCOPY; ELECTRON-MICROSCOPY; CRYSTAL-STRUCTURE; SHORT-RANGE; TEMPERATURE; CATI1-XFEXO3-DELTA; CAXLA1-XFEO3-Y
subject category
Chemistry
authors
Canales-Vazquez, J; Figueiredo, FM; Waerenborgh, JC; Zhou, WZ; Frade, JR; Irvine, JTS
our authors
Filipe Miguel H Lebre R Figueiredo
Principal Researcher