ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 38, Number 8
JKCSEZ 38(8)
April 20, 1994 

A series of samples in the Nd1-xBaxFeO3-y system has been prepared by heating the reactants to1200℃ under an ambient atmosphere, and the solid solutions were identified by X-ray power diffraction analysis. The crystal systems of samples with x = 0.00 and 0.25 were found to be orthorhombic whose local symmetry is similiar to the distorted octahedral with orthoferrite type one, whereas those with x = 0.50 and 0.75 to be the cubic system. Since Fe ions in the solid solutions are a mixed valence state between Fe3+ and Fe4+ ions, the nonstoichiometric chemical formulas could be determined from the mole ratio of Fe4+ ion and oxygen vacacies. According to the Mossbauer spectroscopic analysis, the presence of 5-coordinated FeO5 was evidenced only in the barium compounds along with FeO6, and FeO4, but not in the strontium and calcium compounds. The samples with x = 0.25 and 0.50 show a spectrum of superparamagnetism, which might be due to the formation of a domain of the ferromagnetic interaction between the Fe3+ and Fe4+ ions. The electrical conductivities of all samples are within semiconducting range. Since the Fe4+ ion acts as an electron acceptor level during the electron transfer between the Fe through intermediate O2- ions, the activation energy of the compounds decreases with the increment of Fe4+ content.