Low-temperature co-fired Ni–Ti co-substituted barium ferrites

Abstract

Divalent Ni²⁺ ion and tetravalent Ti⁴⁺ ion equiatomic co-substituted two trivalent Fe³⁺ ions of M-type barium ferrite in the form of Ba(NiTi)_xFe_12-2xO₁₉ with x = 1.0, 1.1, 1.2, 1.3. The samples were prepared using solid state reaction route and added 2.5 wt% Bi₂O₃ to lower sintering temperature. The samples were sintered at 925℃ and 950℃ for 6 h. As the Ni–Ti molar content changed from 1.0 to 1.3, all XRD patterns showed the single phase of the M-type barium ferrite without other intermediate phase. The microstructures were analyzed with scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The saturation magnetization M_s (49.74–29.58 emu/g) and the coercivity H_c (426.44–329.63 Oe) decreased with increasing Ni–Ti composition x and indicated that a decrease of magnetic moment and anisotropy was achieved by substitution of Ni–Ti. These properties attribute to Ni and Ti occupancies at different sites in the barium ferrite crystalline structure.