STUDY OF SUBSTITUTION OF Fe 3+ IONS IN BaFe 12 O 19 CRYSTAL BY Co 2+ -Ti 4+ AND Cu 2+ -Nb 5+ IONS

In this paper, we studied the substitution of Fe 3+ ions in BaFe 12 O 19 crystal by Co 2+ -Ti 4+ and Cu 2+ -Nb 5+ ions. Two systems of single cry stals of BaFe 12-2x Co x Ti x O 19 (with x=0, 0.04, 0.09, 0.13, 0.27, 0.68) and BaFe 12-x (Nb 1/3 Cu 2/3 ) x O 19 (with x = 0, 0.28, 0.44, 0.60) were grown from Bi 2 O 3 melts. Magnetization a and anisotropy constant K 1 of the above samples were measured in the temperature range of 100-300K. For the substitution with Co 2+ -Ti 4+ ions, it was found that when x = 0.09 σ and K 1 increased slightly with x at the beginning and decreased rapidly when x > 0.09 until K 1 → O at x≈ 1.1. In the case of substitutions with Cu 2+ -Nb 5+ , the σ value was nearly the same in the studied compositions and showed a slightly increasing trend with increasing x; while K 1 decreased monotonously with x. Our results were qualitatively discussed with the model of site occupation of substitution ions in the M-type hexagonal ferrite.