Crystallographically Textured and Magnetic LaCu-Substituted Ba-Hexaferrite with Excellent Gyromagnetic Properties

• Published in: Materials 2022-12, Vol.15 (24), p.8792
• Main Authors: Jiao, Zan, Wang, Yuantao, Wei, Meng, Li, Qifan, Li, Ziyu, Sokolov, Alexander S, Yu, Chengju, Jiang, Xiaona, Wu, Chuanjian, Lan, Zhongwen, Sun, Ke, Yu, Zhong, Harris, Vincent G
• Format: Article
• Language: English
• Subjects: Anisotropy; Broadband; Crystallography; Ferromagnetic resonance; Ferromagnetism; Grain size; Magnetic fields; Magnetic properties; Magnetization; Millimeter waves; Morphology; Permeability; Radiation
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma15248792

Excellent gyromagnetic properties of textured, bulk Ba-hexaferrite samples are required for low-loss, self-biased applications for microwave and millimeter-wave (MMW) devices. However, conventionally processed bulk Ba-hexaferrite ceramics typically demonstrate low remanent magnetization values, 4π , of 2.0~3.0 kG, and relatively large ferromagnetic resonance (FMR) linewidths, Δ , of 0.8~2 kOe. These properties lead to the development of high-performance, practical devices. Herein, crystallographically textured Ba-hexaferrite samples, of the composition Ba La Fe Cu O , having excellent functional properties, are proposed. These materials exhibit strong anisotropy fields, , of ~14.6 kOe, high remanent magnetization, 4π , of 3.96 kGs, and a low Δ of 401 Oe at zero-bias field at the Q-band. Concomitantly, the broadband millimeter-wave transmittance was utilized to determine the complex permeability, *, and permittivity, *, of textured hexaferrites. Based on Schlöemann's theory of complex permeability, *, the remanent magnetization, 4π , anisotropy field, , and effective linewidth, Δ , were estimated; these values agree well with measured values.