Cobalt Substitution in CuFe${}_2$O${}_4$ spinel and its influence on the crystal structure and phonons

Abstract

In this work nanometric spinel Co${}_{1-x}$Cu${}_x$Fe${}_2$O${}_4$ powders were obtained by polymeric precursors method at several annealing temperatures between 700 and 1200 ${}^{\circ }$C. The samples were characterized by means of X-ray powder diffraction, confirming the ideal inverse spinel structure for CoFe${}_2$O${}_4$ sample and the tetragonal distorted inverse spinel structure for CuFe${}_2$O${}_4$ sample. Based on FWHM evaluation, we estimated that crystallite sizes varies between 27 and 37 nm for the non-substituted samples. The optical-active modes were determined by infrared and Raman spectroscopies. The phonon spectra showed a local tetragonal distortion for mixed samples.

25 pages, 8 figures