The morphology and electromagnetic properties of MnO₂ obtained in 8 T high magnetic field

MnO₂ powder was synthesized in a high magnetic field (8 T) via a simple route, and the formation mechanism for the grain shape was discussed. The synthesized samples were characterized by XRD, SEM, TEM, and vector network analysis. The morphology of synthesized MnO₂ was sea urchin-like ball chain with a low density center, just like "hollow-like". Throughout the whole frequency range, the dielectric constant and the loss tangent clearly decreased in 8 T high magnetic field. Moreover, the magnetic permeability and the loss tangent increased slightly in the frequency range 213 GHz. Furthermore, the theoretically calculated values of reflection loss showed that when the magnetic field strength 8 T was adopted, the absorption peak became smoother and shifted to a higher frequency.