Nanoarchitectonics of MnO2, nanotubes as sea urchin-like aggregates for dielectric response and microwave absorption with a wide concentration domain

Designing highly reliable and practical owave absorbers is one of the most important research directions in the microwave absorbing field. Many absorbents suffer from concentration -sensitivity and environmental -sensitivity dilemmas in practical applications. Here, sea urchin -like aggregates of MnO2 nanotubes were synthesized by a simple hydrothermal method, which exhibit an outstanding impedance matching characteristic. The composites based on sea urchin -like aggregates of MnO2 nanotubes show excellent microwave absorption performance in a wide concentration domain from 20 wt% to 70 wt.%, corresponding to electrical conductivities from 1.86 x 10(-7) to 1.85 x 10(-5) Sim. Such a wide concentration range of absorbent for excellent microwave absorption is mainly attributed to the beneficial impedance matching properties of sea urchin -like aggregates of hollow nanotubes. A competitive absorption bandwidth of 3.36 GHz is achieved at 1 mm thickness, which can be broadened to 13.4 GHz by structural design. This work shows a new scheme for designing reliable and practical microwave absorbers benefit from the wide absorbent concentration domain.