Site preference for Co/sup 2+/ and Ti/sup 4+/ in Co-Ti substituted barium ferrite

Abstract

Co2+ and Ti4+ substituted M-type barium ferrite, BaFe~z-zxCo,TixOl~, with x from 0 to 0.9 has been prepared using a modified ceramic method and investigated by electron microscopy, vibrating sample magnetometry and Mossbauer spectroscopy. Results show that Coz+ and Ti4+ cations prefer to occupy the 4fv1 and 2b crystallographic sites, with 4fw and 2a sites are only slightly involved as well for x > O.G. These site preferences will significantly weaken the uniaxial anisotropy of this material which is attributed to the contribution of iron ions at the 2b and 4fvl sites. As a consequence, the coercive force of BaFe~z-zxCo,TixOl~ drastically decreases and the magnetization remains almost a constant as x increases.

Static and high frequency magnetic properties of Mn–Co–Zr substituted Ba-ferrite

“…However, only linear decrease in coercivity was found in Co-Ti, Co-Sn and Co-Ir substituted barium ferrite [21][22][23]. It was well known that the coercivity is heavily dependent upon the grain size.…”

The effect of Co and Zr substitution on dc magnetic properties of Ba–Sr ferrite

“…The trend of H c and H a is not same for samples 0.2-1.0. This is due to the fact that H c is dependent on grain size also apart from When compared with other substituents, Ni-Zr [7], Co-Ru [8], Co-Sn [9], Sn-Ru [22], Co-Ti [23], etc., it becomes clear that Zr 4+ and Co 2+ ions enhance M s and decrease H c better than the above reported substituents.…”

La–Zn Substituted Hexaferrites Prepared by Chemical Method

“…The substitutions of La-Zn ions from 0.2 up to 0.6 on the Fe 3+ sites cause the appearance of five different magnetic surroundings and the 12k position is broadened. This position splits into two sublattices, one representing the ions with three nearest magnetic neighbours in the 4f 1 site and other, 12k with two neighbours in the 4f 1 site whereby its value B hf is the smallest at about 36 T [5,12]. The variations of local hyperfine fields B hf (T) and of the relative areas S (%) as a function of x for both (Mx) and (Sk) samples are shown in Figures 2 and 3.…”