Hot-pressing achieved superior performance in Cu/Zn/Sn-doped BaM hexaferrites: Enhanced densification, magnetic hardening, and stable dielectric properties

Conventional solid-state sintering of M-type hexaferrites requires high temperatures and long durations yet often yields inadequate density and coarse grains, limiting functional performance. This limitation is overcome by hot pressing, which applies uniaxial pressure synergistically with a transient liquid phase. This strategy enables rapid densification at a substantially lower temperature of 975 °C, in contrast to over 1100 °C for conventional methods. The resulting ceramics achieve near theoretical density exceeding 98% (98.03-98.22%), a fine-grained uniform microstructure, and superior structural integrity ( R wp  = 2.50-2.83%), properties unattainable by standard sintering. The hot-pressing process also leads to oxygen vacancy reorganization. Consequently, the materials exhibit comprehensively enhanced properties: the optimal composition achieves a high coercivity of 1672.8 Oe, and low dielectric loss (ε″ ≈ 0.93 at 1 MHz) with excellent temperature stability (Δε' as low as 9.23). This work establishes hot pressing as a superior alternative and elucidates the underlying pressure assisted densification and valence modulation mechanism, providing a new design principle for engineering high performance microwave ferrites.