Magnetic susceptibilities and Mossbauer spectra of perovskites A(2)FeNbO(6) (A = Sr, Ba)

Perovskite-type compounds A(2)FeNbO(6) (A = Sr, Ba) mere prepared, Their po wder X-ray diffraction measurements and the Rietveld analysis show that the cations Fe3+ and Nb5+ Oyer the six-coordinate sites of the perovskite stru cture are arranged randomly for Sr2FeNbO6 and some of them order regularly for Ba2FeNbO6. They show magnetic susceptibility maxima at ca. 25 K. Below the temperatures, the divergence of the magnetic susceptibilities measured between the zero-field-cooled condition and the field-cooled condition has been measured. Field-cooled and zero-field-cooled susceptibilities show a h ysteresis below maximum temperatures, These results indicate the existence of a ferromagnetic component in the magnetic moment. Mossbauer spectra meas ured at 6 K comprise a single magnetic hyperfine pattern typical of Fe3+, b ut with a high degree of line broadening. These data are discussed in terms of antiferromagnetic interactions with a ferromagnetic component. (C) 2000 Academic Press.