Submicron pre-sintering grain size effects on the microstructure and magnetic properties of hot-press sintered barium hexaferrite thick films.

Grain size plays an important role in affecting the physical properties of ceramics. In this work, the effects of pre-sintering grain size G 0 of BaFe 12 O 19 (BaM) on the microstructure and magnetic properties of hot-press sintered BaM thick films were studied. Results show that reducing G 0 in submicron scale leads to notable decreases in grain growth activation energy and final sintered grain size. Smaller G 0 makes BaM grains easier to be aligned by magnetic field before sintering and less magnetic domain walls in the sintered film. This increases the c -axis orientation, out-of-plane remanence ratio SQ (>0.9) and coercivity of sintered film. Moreover, the zero-field ferromagnetic resonance linewidth ΔH decreases 54% as G 0 reduces from 1 μm to 0.3 μm. This is attributed to the increased film uniformity with larger SQ and film density D rel at smaller G 0. The above findings enable better understanding on the role of G 0 in improving the magnetic properties of hot-press sintered BaM and other hexaferrite thick films for self-biased microwave devices. [ABSTRACT FROM AUTHOR]