Enhanced microwave absorption of barium cobalt hexaferrite composite with improved bandwidth via c-plane alignment

Functional Magnetic Composites Based on Hexaferrites: Correlation of the Composition, Magnetic and High-Frequency Properties

“…One of the major tasks in creating modern mobile communication devices is the development of new materials which can work in a wide (up to 100 GHz) frequency range in switches, circulators, phase shifters, transceivers, antennas and effective electromagnetic radiation (EMR) absorbers, which improve the electromagnetic compatibilities of devices [1][2][3][4][5]. M-type hexagonal ferrites are one of the most prospective electromagnetic materials for application in the centimeter and millimeter wave range due to the large values of permeability and magnetization, and good dielectric properties at microwave frequencies [6][7][8][9][10]. These materials are magnetically hard with high coercivity and magnetic permeability, and are also characterized by high values of magnetocrystalline anisotropy along the c-axis of the hexagonal structure.…”

Ultra-broadband microwave absorption of (Mn0.2Fe0.2Zn1.2)x substituted Co2Y hexaferrites with a self-aligned sheet stacked, highly c-axis oriented and multi-domain structure

“…Therefore, the grains of the prepared Y-type hexaferrites are oriented along the c -axis (0 0 l ) direction. As previously reported, 25,26 the alignment degree ( ψ ) of the prepared sample can be calculated using eqn (3) and (4):where I ( hkl ) represents the relative intensity of oriented ( hkl ) crystalline plane reflection, ψ represents the alignment degrees of the aligned samples, and Φ ( hkl ) represents the angle between the ( hkl ) crystalline plane and the c -plane. Accordingly, based on lattice parameters obtained from the Rietveld refined XRD pattern, the c -plane alignment degree ( ψ ) of x = 0.5, x = 1.0, and x = 1.25 samples is calculated to be 0.739, 0.715 and 0.725, respectively, indicating that the prepared samples have a high c -plane alignment degree.…”

“…The RL min value of the Co 2 Y@PANI/(00 h ) BaM/PVB composite reached −66.9 dB at 11.6 GHz with a thin thickness of 1.9 mm, and the EAB max was about 6.32 GHz. Wei et al 25 prepared a highly oriented BaCo 2 Fe 16 O 27 (Co 2 W)/paraffin composite with 45 vol% particles subjected to a rotational orientation in an external magnetic field. The highly oriented Co 2 W composite showed higher permeability, stronger RL min and broader EAB max compared to its unaligned counterpart in the frequency range of 8–18 GHz.…”

Design and Fabrication of Layered Electromagnetic Interference Shielding Materials: A Cost-Effective Strategy for Performance Prediction and Efficiency Tuning

“…These values are used to simulate the shielding structures for the K-band due to the minimum frequency dispersion of electromagnetic parameters at the microwave frequencies, which can be attributed to the ceasing of various polarization mechanisms. − Further, the ferrimagnetic resonance (FMR) frequency of barium hexaferrite is well above 40 GHz, leading to a stable permeability up to its FMR frequency . As the FMR frequency of barium hexaferrite is high, Snoek’s limit predicts a low permeability (∼1.32) for the compound, leading to lower dispersion of permeability even after resonance. , Furthermore, in High Frequency Structure Simulator (HFSS) software, a frequency response is predicted for the materials at the simulated-frequency region based on the input parameters (electromagnetic parameters) and the frequency at which the parameters are measured. The simulations are carried out based on this predicted frequency response of materials.…”

“…45 As the FMR frequency of barium hexaferrite is high, Snoek's limit predicts a low permeability (∼1.32) for the compound, leading to lower dispersion of permeability even after resonance. 46,47 Furthermore, in High Frequency Structure Simulator (HFSS) software, a frequency response is predicted for the materials at the simulated-frequency region based on the input parameters (electromagnetic parameters) and the frequency at which the parameters are measured. The simulations are carried out based on this predicted frequency response of materials.…”