Structural, magnetic and microwave properties of barium hexaferrite thick films with different Fe/Ba mole ratio

• Single phase BaM thick films with different Fe/Ba mole ratio are prepared.
• Site preference of Fe ion is estimated by Mössbauer spectroscopy.
• Magnetization and magnetocrystalline ansisotropy is found maximum for 5.5 mole ratio.
• Absorption frequency found to vary with the mole ratio.

Barium hexaferrite (BaFe12O19) thick films (∼60 µm) with different BaO·xFe2O3 mole ratio (x=5.0–6.0) were prepared by screen printing method. X-ray diffraction analysis confirmed the formation of single phase BaFe12O19 (BaM). Preferential site occupation of Fe3+ ion at five different crystallographic sites, with varied mole ratio was measured by Mössbauer spectroscopy. Vacancy fraction found to be higher at 4f1, 4f2 and 2b sites for mole ratio 5.5 and 5.0 respectively. Magnetic measurement shows that the magnetization (M) and magnetocrystalline anisotropy field (Ha) depends upon mole ratio. M and Ha are found to be maximum for mole ratio 5.5, while the coercivity (Hc) remains constant. Reflection losses (RL) in the frequency range of 12–18 GHz were also studied. Present investigation demonstrates the effect of mole ratio on structural, magnetic and microwave absorption properties of BaM thick films for microwave device applications.