Investigation on Zn-Sn co-substituted M-type hexaferrite for microwave applications

Highlights: • Partial Zn²⁺ ions tend to occupy 2b sublattice with high Zn-Sn substitution contents. • Oriented M-type hexaferrite exhibits a preferred orientation along c axis. • Self-biased M-type hexaferrite compacts with high squareness ratio (M_r/M_s = 0.81) are obtained. - Abstract: Zn-Sn co-substituted M-type hexaferrite with compositions of Ba(ZnSn)_xFe_12−2xO₁₉ (x = 0–1.2 in step of 0.2 and x = 1.0–1.2 in step of 0.04) were synthesized via a solid reaction method. Pure M phase was observed by XRD analysis for all samples. With increase of substitution contents, morphological features exhibited a shrinkage tendency in grain size. Meanwhile, the structure of samples also became more homogeneous and compact due to the enhancement of samples' densities (ρ). In terms of magnetic properties, the saturation magnetization (M_s) decreased slightly from 57.62 emu/g to 45.57 emu/g as x increased from 0 to 1.0, and then it reduced sharply to 26.23 emu/g when x reached to 1.2, which might be attributed to occupancies of partial Zn²⁺ ions on 2b sublattice. The Curie temperature (T_c) decreased remarkably from 432 °C to 230 °C. Moreover, oriented BaM with a high squareness ratio (0.81) was achieved to match the applications in microwave devices.