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

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 degrees C, but all samples consist of the main spinet phase in combination of a small amount of a foreign LaFeO3 phase after doping. When the precursor is calcined at 900 degrees 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 degrees C increases with increasing La3+ substitution. (C) 2014 Elsevier B.V. All rights reserved.