Structural, Magnetic and Microwave Characterization of Polycrystalline Z-Type Sr 3 Co 2 Fe 24 O 41 Hexaferrite

• Published in: Materials Vol. 13; no. 10
• Main Authors: Kolev, Svetoslav, Peneva, Petya, Krezhov, Kiril, Malakova, Tanya, Ghelev, Chavdar, Koutzarova, Tatyana, Kovacheva, Daniela, Vertruyen, Benedicte, Closset, Raphael, Maria Tran, Lan, Zaleski, Andrzej
• Format: Journal Article
• Language: English
• Published: Switzerland 20.05.2020
• Subjects: reflection losses; Z-type hexaferrite; microwave properties; magnetic phase transition
• ISSN: 1996-1944; 1996-1944

We report results on the structural and microwave properties and magnetic phase transitions in polycrystalline Sr Co Fe O hexaferrite synthesized by sol-gel auto-combustion and acting as a filler in a composite microwave absorbing material. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves revealed a change in the magnetization behavior at 293 K. The reflection losses in the 1-20 GHz range of the Sr Co Fe O powder dispersed homogeneously in a polymer matrix of silicon rubber were investigated in both the absence and presence of a magnetic field. In the latter case, a dramatic rise in the attenuation was observed. The microwave reflection losses reached the maximum value of 32.63 dB at 17.29 GHz in the Ku-band. The sensitivity of the microwave properties of the composite material to the external magnetic field was manifested by the appearance of new reflection losses maxima. At a fixed thickness of the composite, the attenuation peak frequency can be adjusted to a certain value either by changing the filling density or by applying an external magnetic field.