La-substituted W-type barium–nickel ferrites for tunable andhigh-performance electromagnetic wave absorption

W-type barium–nickel ferrite (BaNi2Fe16O27) is a highly promising material for electromagnetic wave （EMW） absorption be cause of its magnetic loss capability for EMW,low cost,large-scale production potential,high-temperature resistance,and excellen chemical stability.However,the poor dielectric loss of magnetic ferrites hampers their utilization,hindering enhancement in their EMW absorption performance.Developing efficient strategies that improve the EMW-absorption performance of ferrite is highly desired but re mains challenging.Here,an efficient strategy substituting Ba2+with rare earth La3+in W-type ferrite was proposed for the preparation o novel La-substituted ferrites (Ba1-x Lax Ni2Fe15.4O27).The influences of La3+substitution on ferrites’EMW-absorption performance and the dissipative mechanism toward EMW were systematically explored and discussed.La3+ efficiently induced lattice defects,enhanced defectinduced polarization,and slightly reduced the ferrites’bandgap,enhancing the dielectric properties of the ferrites.La3+also enhanced the ferromagnetic resonance loss and strengthened magnetic properties.These effects considerably improved the EMW-absorption perform ance of Ba1-x Lax Ni2Fe15.4O27 compared with pure W-type ferrites.When x=0.2,the best EMW-absorption performance was achieved with a minimum reflection loss of-55.6 dB and effective absorption bandwidth （EAB） of 3.44 GHz.