5G communication commercialization is accelerating in many countries. At present, a large number of communication materials are deployed to transmit millimeter waves for 5G base stations. However, it brings huge energy consumption due to the shortcomings of the current materials. Therefore, a novel soft magnetic material with high magnetic permeability and low dielectric constant is urgently needed to reduce the energy loss of 5G base stations. In this work, a series of CoBiNi alloys were prepared using the hydrothermal reduction method, with bismuth (Bi) as the dopant. The results indicate that Bi can regulate the magnetic permeability of soft magnetic materials; the permeability of the Co20Bi5Ni75 alloy fluctuates stably around 1.50 within the frequency range of 14.00–18.00 GHz. The saturation magnetization exhibits an upward trend with increasing Bi doping, with the Co20Bi5Ni75 sample reaching a saturation magnetization of 73.11 emu/g. The coercivity and residual magnetization characteristics confirm that Co20Bi5Ni75 is a typical soft magnetic material. The microwave return loss (RL) of the Co20Bi5Ni75 alloy was consistently higher than −6.89 dB across the 1.00–18.00 GHz frequency range when the sample thickness was 5 mm. The increased magnetic permeability of the Co20Bi5Ni75 alloy is attributed to the ability of Bi3+ to suppress carrier migration, thereby increasing the resistivity of the crystal structure and consequently improving the material’s magnetic permeability. These findings provide new insights into the preparation of high-permeability soft magnetic materials.
Gao et al. (Sat,) studied this question.