Coexistence of Zn and Fe ions influenced magnetic and microwave shielding properties of Zn-doped SrFe12O19 ferrites

•Crystal structure and Raman spectra of Zn-doped SrM hexaferrites.•The Zn2+ doping results in the coexistence of Fe3+ and Fe4+ ions.•Hard magnetic properties remain unchanged by the Zn doping in SrM.•Above 90% microwave energy being absorbed. We present the structural characterization, valence change of Fe, Raman spectra, and magnetic and microwave shielding properties of polycrystalline SrFe12-xZnxO19 (x = 0–1) samples. X-ray diffraction and Raman analyses indicated the samples having the M-type hexaferrite structure. The Zn doping caused a remarkable change in the lattice constants. Investigating magnetic hysteresis loops, we found an enhanced saturation magnetization (Ms) as increasing x from 0 to 0.1, and a reduced Ms as x > 0.1. Nearly the same tendency was also observed for the coercive force. Such changes have been thought to the Zn substitution and the valence change of Fe, as affirmed from analyzing the X-ray absorption data. Considering the shielding properties, we observed the samples with a thickness of 1.8 mm showing a low reflection loss. Among the investigated samples, the sample with x = 0.4 had the lowest reflection loss of about −20 dB at frequency of 11.7 GHz, corresponding to ~99% microwave energy being absorbed. We have considered that both dielectric and magnetic losses contribute to the microwave-absorption properties of SrFe12-xZnxO19.