Synthesis and electromagnetic properties of La-doped Ni–Zn ferrites

• Synthesizing Ni0.8Zn0.2LaxFe2−xO4 (X=0–0.1) by a sol–gel method.
• Preparing Ni0.8Zn0.2LaxFe2−xO4 with nanometer scale grains.
• The doping of La possesses good electromagnetic properties.
• Potential applications in magnetic materials and microwave absorbers.

The La3+ doped spinel ferrites, Ni0.8Zn0.2LaxFe2−xO4, were prepared by a sol–gel method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). Results show that La3+ can completely substitute into the lattice of Ni0.8Zn0.2Fe2O4 and exist mostly in the form of lamellar structure. Ni0.8Zn0.2LaxFe2−xO4 (X=0–0.1) show the behaviors of the soft magnets and the saturation magnetization (Ms) decreases with the increasing of La3+ content. The electromagnetic property of Ni0.8Zn0.2La0.06Fe1.94O4 is below −10 dB at 3.1–5.9 GHz and its minimum loss value is −15.43 dB at 5.1 GHz. Therefore, the introduction of La3+ improves the microwave absorbing properties of Ni0.8Zn0.2Fe2O4.