The phase equilibrium relationship of the Bi2O3–Fe2O3–Nd2O3 system at 973 K was established by means of X-ray diffraction. The phase diagram contains 9 single-phase regions, 5 two-phase regions, 7 three-phase regions and no ternary compounds. There are three solid solutions of Bi1.446Nd0.554O3-type, R3c-BiFeO3 and Pnma-NdFeO3. The lattice parameters of the Nd1-xBi x O3 compound increase with increasing Bi2O3 content, but the XRD peaks shift to lower 2θ values when x is 0–0.75. The effect of different mass percentages of two phases, NdFeO3 and Bi25FeO40, on the performance of the sample is explored. When the mass percentage of the second phase Bi25FeO40 increases, the magnetic properties of the samples decrease instead. The sample with a mass ratio of 59 % Bi25FeO40 shows the best adsorption performance. The effective bandwidths of the samples are 2.12 GHz, 2.76 GHz and 2.25 GHz when the mass percentage of the second phase is 17 wt.%, 59 wt.%, and 77 wt.%, respectively.