Synergistic effect of V2O5 and Bi2O3 on the grain boundary structure of high-frequency NiCuZn ferrite ceramics

Abstract High-frequency soft magnetic ferrite ceramics are desired in miniaturized and efficient power electronics but remain extremely challenging to deploy on account of the power loss ( P cv ) at megahertz frequencies. Here, we prepared NiCuZn ferrite with superior high-frequency properties by V 2 O 5 and Bi 2 O 3 synergistic doping, which proves to be a potent pathway to reduce P cv of the ferrite at megahertz frequencies. The sample doped with 800 ppm V 2 O 5 and 800 ppm Bi 2 O 3 yielded the most optimized magnetic properties with a P cv of 113 kW/m 3 (10 MHz, 5 mT, 25 ° C), an initial permeability ( μ i ) of 89, and a saturation induction ( B s ) of 340 mT, which is at the forefront of the reported results. These outstanding properties are closely related to the notable grain boundary structure, which features a new type of nano-Bi 2 Fe 4 O 9 phase around ferrite grains and a Ca/Si/V/O amorphous layer. Our results indicate great strides in correlating the grain boundary structure with multiple-ion doping and set the scene for the developing high-frequency soft magnet ferrites.