LAUSR

Abstract Low-density ordered mesoporous CoFe2O4 (O CFO) and CoLa0.12Fe1.88O4 (O CLFO) are prepared by nanocasting method using mesoporous silica SBA-15 as a hard-template. The crystal structure, surface chemical state, magnetic properties and electromagnetic parameters are characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption measurement, X-ray photoelectron spectroscopy, physical property measurement system and vector network analyzer. The results show that all the samples formed a single phase with cubic spinel structure. Meanwhile O CFO and O CLFO possess a highly ordered mesostructure. Comparing with particle CoFe2O4 (P-CFO), O CFO with high specific surface area exhibits lower magnetic saturation (Ms), higher imaginary part of complex permittivity (e′′) and imaginary part of the complex permeability (μ′′). The minimum reflection loss (RL) of O CFO reaches −27.36 dB with a matching thickness of 3.0 mm. The enhancement of the microwave absorbing performances of O CFO can be mainly attributed to the good impedance matching, high electromagnetic wave attenuation and multiple reflections of electromagnetic wave originated from the ordered mesoporous structure. The Ms of O CLFO decreases after La3+ doping, while the specific surface area, coercivity value, e′′ and μ′′ of O CLFO increase. The minimum RL of O CLFO reaches −46.47 dB with a thickness of 3.0 mm, and the effective absorption frequency bandwidth reaches 4.9 GHz.