Preparation and Microwave Absorption Properties of the Fe/TiO₂/Al₂O₃ Composites

Abstract

To reduce the imbalance of impedance matching between the magnetic metal nanowires and free space, Fe/TiO2 core/shell nanowire arrays with different diameters were fabricated in the templates of anodic aluminum oxide membranes by electrodeposition. The influences of the microstructure on the microwave absorption properties of the Fe/TiO2/Al2O3 composites were studied by the transmission/reflection waveguide method. It was demonstrated experimentally that both the interfacial polarization and the diameter of the Fe/TiO2 core/shell nanowires have critical effects on the microwave absorption properties. We also investigated the angle dependence of the microwave absorption properties. Due to the interfacial polarization and associated relaxation, the Fe/TiO2/Al2O3 composites exhibited optimal microwave absorption properties when microwave propagation direction was accordant with the axis of the nanowires. Finally, we managed to obtain an optimal reflection loss of below [Formula: see text]10[Formula: see text]dB (90% absorption) over 10.2–14.8[Formula: see text]GHz, with a thickness of 3.0[Formula: see text]mm and the minimum value of [Formula: see text]39.4[Formula: see text]dB at 11.7[Formula: see text]GHz.

Constructing magnetic/dielectric dual loss and phonon/electron thermal carriers γ-Al2O3-based yolk–shell microspheres to collaboratively advance microwave absorption and heat conduction

“…The ABW max of 15.44 GHz is 2.35 times as large as g-Al 2 O 3 YSMSs and 1.93-6.176 times as large as other reported fillers; meanwhile, the ABW max /d of 4.74 GHz mm À1 is 2.38 times as large as g-Al 2 O 3 YSMSs and 1.27-4.23 times as large as other reported fillers. [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68] In addition, stronger absorption (RL min = À55.6 dB) can be found in g-Al 2 O 3 @Fe 3 O 4 @C YSMSs, which is significantly higher than most other absorbers. [51][52][53]55,56,59,[62][63][64]66,68 The absorption bands (RL o À10 dB) of g-Al 2 O 3 @FeAl 2 O 4 @Fe@C and g-Al 2 O 3 @Fe 3 O 4 @C YSMSs, compared with that of g-Al 2 O 3 YSMSs (Fig.…”

“…[51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68] In addition, stronger absorption (RL min = À55.6 dB) can be found in g-Al 2 O 3 @Fe 3 O 4 @C YSMSs, which is significantly higher than most other absorbers. [51][52][53]55,56,59,[62][63][64]66,68 The absorption bands (RL o À10 dB) of g-Al 2 O 3 @FeAl 2 O 4 @Fe@C and g-Al 2 O 3 @Fe 3 O 4 @C YSMSs, compared with that of g-Al 2 O 3 YSMSs (Fig. 8a2), move toward lower frequency and thinner sample thickness (Fig.…”

“…Overall, the ABW max /d values of 4.49-4.74 GHz mm À1 outperform those of most other materials (1.12-3.74 GHz mm À1 ). [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68] Therefore, it can be concluded that the optimal synthesis conditions for the YSMSs are T a = 600-700 1C and b = 8 : 2. The optimal EMWAPs could be explained by the interaction of interface, component, defect, and yolkshell structure.…”