Influence of A-site doping barium on structure, magnetic and microwave absorption properties of LaFeO3 ceramics powders

Abstract In this paper, the effect of Ba2+ ions A-site doping LaFeO3 on structure, magnetic properties and microwave absorption properties was investigated by the sol-gel method. According to the TEM and FullProf refinement results, the structure of LaFeO3 changes from orthogonal (SG: Pnma) to cubic (SG: Pm-3m) when the Ba doping amount is x = 0.4. The SEM image shows that the particles size tends to decrease with the increase of Ba content. The production of weak ferromagnetism indicates that Ba doping has a significant effect on the magnetic properties of LaFeO3. The Neel temperature (TN) decreases significantly with the increase of Ba doping amount. An appropriate amount of Ba doping can effectively increase the dielectric and magnetic loss of LaFeO3 ceramics powders. The increase permittivity (e′) may have been attributed to the hopping spin of the electrons between the Fe3+ and Fe4+ ions with the Ba2+ ions doping. The minimum reflection loss (RL) of La0.9Ba0.1FeO3 at 6.72 GHz reached –30.04 dB, its effective bandwidth (RL ≤ –10 dB) is 2.1 GHz, and the matching thickness is only 3.2 mm. These results indicate that Ba doping can effectively control the microwave absorption properties of LaFeO3, especially in the C-band.