Phase formation, magnetic properties and Raman spectra of Co-Ti co-substitution M-type barium ferrites

© 2015, Springer-Verlag Berlin Heidelberg. In this paper, Co–Ti ions co-substituted M-type barium ferrite materials [Ba(CoTi)xFe12−2xO19, x = 1.15, 1.20, 1.25 and 1.30] were synthesized by solid-state reaction method. The ferrites, with sintering at 1,200 °C for 4 h, all exhibit the single phase M-type barium ferrite structure. However, there are obvious differences on properties among different amounts of Co–Ti substitution, basing on the same phase formation of M-type barium ferrites. With x increasing from 1.20 to 1.25, magnetic properties, including saturation magnetic flux density (Bs), residual magnetic flux density (Br), initial permeability (μα), saturation magnetization (Ms), coercivity (Hc) and Q-factor, have an obvious change. This is attributing to that Co and Ti occupancies at different sites in the barium ferrite crystalline structure bring the change of magnetocrystalline anisotropy. The appropriate content of Co–Ti substitution makes the magnetocrystalline anisotropy transform from uniaxial to planar anisotropy. Meanwhile, this difference also is confirmed by Raman spectroscopy. The spectra are recorded from 200 to 3,200 cm⁻¹ in the room temperature. The occupancy of Co²⁺ and Ti⁴⁺ ions on the Fe³⁺ sites causes difference in intensity and Raman bands, which also corroborate the changes of Co–Ti occupation and magnetocrystalline anisotropy from another perspective.