Lightweight and high-efficiency microwave absorption materials with tunable electromagnetic properties is a highly sought-after goal and a great challenge for researchers. In this work, a simple strategy of confinedly...Lightweight and high-efficiency microwave absorption materials with tunable electromagnetic properties is a highly sought-after goal and a great challenge for researchers. In this work, a simple strategy of confinedly implanting small NiFe204 clusters on reduced graphene oxide is demonstrated, wherein the magnetic clusters are tailored, and more significantly, the electromagnetic properties are highly tuned. The microwave absorption was efficiently optimized yielding a maximum reflection loss of -58 dB and - 12 times broadening of the bandwidth （at -10 dB）. Furthermore, tailoring of the implanted magnetic clusters successfully realized the selective-frequency microwave absorption, and the absorption peak could shift from 4.6 to 16 GHz covering 72% of the measured frequency range. The fascinating performances eventuate from the appropriately tailored clusters, which provide optimal synergistic effects of the dielectric and magnetic loss caused by multi-relaxation, conductance, and resonances. These findings open new avenues for designing microwave absorption materials in future, and the well-tailored NiFe204-rGO can be readily applied as a multi-functional microwave absorption material in various fields ranging from civil and commerce to military and aerospace.展开更多
Nitrogenation of SmFelolVIo2 powders was performed in a self-made furnace under a high-purity N2 atmo- sphere up to 40 MPa at 500 ℃. Upon nitrogenation at atmospheric pressure, the lattice parameters a and c increase...Nitrogenation of SmFelolVIo2 powders was performed in a self-made furnace under a high-purity N2 atmo- sphere up to 40 MPa at 500 ℃. Upon nitrogenation at atmospheric pressure, the lattice parameters a and c increase by 0.5% and 2.7%, respectively, whereas the Curie temperature Tc increases from 519 to 633 K. With further increasing the nitrogenation pressure to 20 and 40 MPa, the 1：12 main phase starts to decompose and a large amount of Mo and a-Fe precipitates. This leads to variation of Mo concentration in the 1：12 phase and causes a sharp decrease in Tc and in the coercivity. The relative complex permittivity and permeability of paraffin-SmFeloMO2 composites show multi-resonant behavior. After nitrogenation, the magnetic loss of the powders decreases, which may originate from the influence of eddy currents due to the increase in the particle size.展开更多
基金This work was supported by the National Natural Science Foundation of China （NSFC） （Nos. 11774027, 51132002, 51072024 and 51372282）.
文摘Lightweight and high-efficiency microwave absorption materials with tunable electromagnetic properties is a highly sought-after goal and a great challenge for researchers. In this work, a simple strategy of confinedly implanting small NiFe204 clusters on reduced graphene oxide is demonstrated, wherein the magnetic clusters are tailored, and more significantly, the electromagnetic properties are highly tuned. The microwave absorption was efficiently optimized yielding a maximum reflection loss of -58 dB and - 12 times broadening of the bandwidth （at -10 dB）. Furthermore, tailoring of the implanted magnetic clusters successfully realized the selective-frequency microwave absorption, and the absorption peak could shift from 4.6 to 16 GHz covering 72% of the measured frequency range. The fascinating performances eventuate from the appropriately tailored clusters, which provide optimal synergistic effects of the dielectric and magnetic loss caused by multi-relaxation, conductance, and resonances. These findings open new avenues for designing microwave absorption materials in future, and the well-tailored NiFe204-rGO can be readily applied as a multi-functional microwave absorption material in various fields ranging from civil and commerce to military and aerospace.
基金financially supported by the National Natural Science Foundation of China (No. 51261001)Liaoning Provincial Natural Science Foundation (No. 2013020105)Shenyang Science and Technology Foundation (No. F13-316-139)
文摘Nitrogenation of SmFelolVIo2 powders was performed in a self-made furnace under a high-purity N2 atmo- sphere up to 40 MPa at 500 ℃. Upon nitrogenation at atmospheric pressure, the lattice parameters a and c increase by 0.5% and 2.7%, respectively, whereas the Curie temperature Tc increases from 519 to 633 K. With further increasing the nitrogenation pressure to 20 and 40 MPa, the 1：12 main phase starts to decompose and a large amount of Mo and a-Fe precipitates. This leads to variation of Mo concentration in the 1：12 phase and causes a sharp decrease in Tc and in the coercivity. The relative complex permittivity and permeability of paraffin-SmFeloMO2 composites show multi-resonant behavior. After nitrogenation, the magnetic loss of the powders decreases, which may originate from the influence of eddy currents due to the increase in the particle size.
