MOE Key Laboratory of Materials Physics and Chemistry in Extraordinary Conditions;
Shaanxi Key Laboratory of Macromolecular Science and Technology;
School of Chemistry and Chemical Engineering;
Northwestern Polytechnical University;
Xi’an 710072;
China;
China Academy of Launch Vehicle Technology;
Beijing 100076;
China;
Minmetals exploration&development CO.LTD;
Beijing 100010;
China;
hierarchical magnetic-dielectric composites; hollow hydrangea-like structure; impedance matching; nitrogen doped NiO/Ni/C; microwave absorption;