STUDY OF NONSTOICHIOMETRY AND PHYSICAL-PROPERTIES OF THE CAXEU1-XFEO3-Y SYSTEM

A series of samples of the CaxEu1-xFeO3-y(x = 0.00, 0.25, 0.50, 0.75, and 1.00) system has been prepared at 1,250-degrees-C under an atmosph eric air pressure. X-ray diffraction analysis of the solid solution as signs the structure of the compositions of x = 0.00, 0.25, 0.50, and 0 .75 to the orthoferrite-type orthorhombic system, and that of x = 1.00 to the brownmillerite-type orthorhombic one. The mole ratios of Fe4ion in the solid solutions or tau values were determined by the Mohr's salt analysis and nonstoichiometric chemical formulas of the system w ere formulated from x, tau, and y values. From the result of the Mossb auer spectroscopy, the coordination and magnetic property of the iron ion are discussed. The electrical conductivities are measured as a fun ction of temperature. The activation energy is minimum at the composit ion of x = 0.25. The conduction mechanism can be explained by the hopp ing of electrons between the mixed valences of Fe3+ and Fe4+ ions.