Rare-earth doped Nano-barium ferrite films combining characteristics of nano-materials and thin films have good prospects in magnetic recording and Electromagnetic wave absorption material. We succeed preparing Rare-earth doped Nano-barium films by Sol-gel technique, and discussing magenetic properties and electromagnetic microwave absorption properties of the films prepared by changing the rare-earth doped rate and the rare earth categories (La³⁺,Ce³⁺). Corresponding to other element doped Barium ferrite, the maximum loss tangent values at the frequency of 9.6 GHz of La doped and Ce doped Barium ferrite films increased about 110% and 196% respectively.

The phase composition and microstructure of the BaLn_xFe_12-xO₁₉ (Ln included La and Ce, x=0, 0.2…8) films were characterized by X-ray Diffraction Analysis (XRD), Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM). The quantitative compositional analysis of the films was measured by X-ray Energy Dispersive Analysis (EDS). The complex permittivity and complex permeability which characterized microwave absorption properties of the films were measured by Microwave Vector Network Analyzer. The magnetic properties were measured by Vibrating Sample Magnetometer (VSM).

Results showed that: (1) according to the non-stoichiometric amount of Fe:Ba ratio, we obtained good electromagnetic properties of the single phase composition, and at Fe:Ba=9, we got the single phase composition of Rare-earth doped Nano-barium ferrite films; (2) the grain size of barium ferrite films doped by La was 40nm-80nm, length of it was 100nm, and the grain size of barium ferrite films doped by Ce was 60nm-100nm, length of it was 150nm; (3) the maximum coercivity（Hc）of La doped Barium ferrite films (BaLa_xFe_12-xO₁₉) was 366.33 kA/m at x=0.2, and the maximum saturation magnetization (Ms) of them was 49.06 A•m2/kg at x=0.6. In magnetic characteristics research of Ce doped Barium ferrite films(BaCe_xFe_12-xO₁₉), the maximum coercivity（Hc）was 326.93 kA/m at x=0.6, the maximum saturation magnetization (Ms) was 26.70 A•m2/kg at x=0.4; (4) Both La doped and Ce doped Barium ferrite films had good microwave absorption properties in the range of 9.5GHz～10.5GHz.

Keywords: Sol-Gel; Barium ferrite films; Doped; Magnetic properties; Microwave absorption properties