Magnetic properties of the mixed spinel Co 1+x Sn x Fe 2−2x O 4

Abstract

The structural and magnetic properties of the mixed spinel Co1+xSnxFe2−2xO4 system for 0.1≤x≤0.5 have been studied by means of X‐ray diffraction, magnetization, a.c. susceptibility and Mossbauer effect measurements. X‐ray intensity calculations indicate that Sn4+ ions occupy only octahedral (B) sites replacing Fe3+ ions and the added Co2+ ions substitute for A‐site Fe3+ ions. The lattice constants are determined and the applicability of Vegard's law has been tested. The Mossbauer spectra at 300 K have been fitted with two sextets in the ferrimagnetic state corresponding to Fe3+ at tetrahedral (A) and octahedral (B) sites for x≤0.4. The Mossbauer intensity data show that Sn possesses a preference for the B‐site of the spinel. As expected, the hyperfine field and Curie temperature determined from a.c. susceptibility decreases with increasing Sn content. The variation of the saturation magnetic moment per formula unit measured at 77 and 300 K with Sn content is satisfactorily explained on the basis of Neel's collinear spin ordering model for x=0.1–0.4.