Enhanced microwave absorption properties of Fe nanotubes fabricated by a facile gas bubble-engaged assembly technique

Electromagnetic (EM) characteristics of polymorphic Fe nanotubes (INTs) fabricated by a facile gas bubble-engaged assembly technique were studied at 2-18 GHz. The Fe(2+) concentration was varied to modulate the tube structure, the characteristics of which are closely related to its resulting microwave absorption properties. INTs with large aspect ratios, thick tube walls and small inner diameters were easy to produce at high Fe(2+) concentrations. They showed a strong absorption peak of -22.4 dB at 10.4 GHz and a bandwidth (<= -10 dB) of 12 GHz because of proper EM matching and high dielectric loss.