Coercive force of Co–Ni–Li spinel ferrite particles synthesized through co-precipitation, hydrothermal treatment, and etching in hydrochloric acid

Abstract

Co–Ni and Co–Ni–Li spinel ferrite particles were synthesized via chemical co-precipitation, hydrothermal treatment, and etching in hydrochloric acid. The particles were approximately 30 nm in size and showed typical XRD patterns of spinel structure with a lattice constant of 0.838 nm, similar to that in Fe3O4 crystals. The coercive force was 227 kA m−1 and 508 kA m−1 for Co–Ni and Co–Ni–Li spinel ferrite particles, respectively. The magnetic anisotropy field in Co–Ni–Li spinel ferrite particles estimated from rotational hysteresis losses was remarkably higher than that of Co–Ni spinel ferrite particles. Although the A- and B-sites in the spinel structure were considered to have been filled by metal ions in both particles, the positive charge calculated from the composition of Co–Ni–Li spinel ferrite particles was smaller than that in the Co–Ni spinel ferrite particles. Some defects introduced in the particles due to the composition may give some effects on the high coercive force.