Structure and magnetic properties evolution of nickel–zinc ferrite with lanthanum substitution

•Ni0.5Zn0.5LaxFe2–xO4 was synthesized by solid-state reaction at low temperatures for the first time.•Change of lattice constants for Ni0.5Zn0.5LaxFe2–xO4 was explained.•The magnetic properties of Ni0.5Zn0.5LaxFe2–xO4 can be precisely tailored by controlling the composition as well as the calcination temperature.

La3+-doped Ni–Zn ferrites with a nominal composition of Ni0.5Zn0.5LaxFe2–xO4 (where x=0–0.3) are prepared by solid-state reaction at low temperatures. X-ray diffraction data shows that single phase Ni0.5Zn0.5Fe2O4 is obtained at 600 °C, but all samples consist of the main spinel phase in combination of a small amount of a foreign LaFeO3 phase after doping. When the precursor is calcined at 900 °C, the lattice constants of the ferrites initially increase after La3+ doping, but then become smaller with additional La3+ doping. The addition of La3+ results in a reduction of crystallite size. Magnetic measurement reveals that the specific saturation magnetization (Ms) of the as-prepared ferrites decreases with increasing La3+ substitution, while the coercivity (Hc) of Ni0.5Zn0.5LaxFe2–xO4 obtained above 800 °C increases with increasing La3+ substitution.

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