Constructing dendrite-flower-shaped Fe3O4 crystals in glass-ceramic materials as novel broadband high-efficient electromagnetic wave absorbers

•A strategy for forming dendrite-flower-like Fe3O4 hierarchical structure is proposed.•The geometric effect of Fe3O4 contributes to extend the Snoek limit.•Multiple transmission-absorption mechanism is mediated by the glass phase and the 3D dendrite-flower-like crystals.•The impedance matching and the microwave loss ability are improved due to the synergistic absorption mechanism.•This strategy is expected to be used to the design of new compositional systems of high-performance microwave absorbers.