Microwave electromagnetic and absorption properties of Nd_2Fe_(14)B/alpha-Fe nanocomposites in the 0.5-18 and 26.5-40 GHz ranges

摘要

Nd_2Fe_(14)B/alpha-Fe nanocomposites were prepared using a melt-spinning method, subsequent annealing treatment, and ball milling. The complex permittivity and permeability of the composites were measured in the 0.5-18 and 26.5-40 GHz frequency ranges. The permeability spectra of the Nd_2Fe_(14)B/alpha-Fe nanocomposites exhibit relaxation and resonance type characteristic in the 0.5-18 and 26.5-40 GHz frequency ranges, respectively. The resonance frequency (f_r) of Nd_(10)Fe_(78)Co_5Zr_1B_6 nanocomposite is 30 GHz due to the large anisotropy field (H_A). However, the resonance frequency of the Nd_2Fe_(14)B/alpha-Fe sample is lower than that of Nd_2Fe_(14)B, due to the decrease of H_A induced by the exchange interaction between hard and soft magnetic phases. These samples also showed good microwave absorption performance (reflection loss: <-20 dB) in 9, 17, and 35-38 GHz with matching thicknesses of 2, 1.2, and 0.37 mm, respectively. Therefore, Nd_2Fe_(14)B/alpha-Fe nanocomposites are thought to be a potential candidate for thinner microwave absorbers not only in the centimeter wave but also in the millimeter wave band.