The crystal structure and magnetic properties of Ba2−xSrxCo2Fe12O22

Abstract

We have synthesized the Ba2−xSrxCo2Fe12O22 samples (x = 0.1, 0.2, 0.3, 0.4, 0.5) by the solid-state reaction method and investigated their crystalline and magnetic properties by X-ray diffractometer (XRD), Mössbauer spectrometer, vibrating sample magnetometer, and network analyzer. XRD patterns show that all samples are rhombohedral with space group R-3m. The lattice constants a0 and c0 decrease with Sr substitution due to smaller ion radius of Sr2+ (1.27 Å) than that of Ba2+ (1.43 Å). The Mössbauer spectroscopy measurements show that the relative area ratios of Fe ion were maintained constant regardless of the Sr concentration. However, average magnetic hyperfine field slightly increased with the Sr concentration. This observation agrees with the fact that the saturation magnetization (Ms) linearly increases due to the increasing super-exchange interaction, originated from the difference in the ionic radius between Ba2+ and Sr2+. To investigate its properties at high frequency range, all samples were sintered at 1100 °C, and complex permeability and permittivity were measured by network analyzer between 100 MHz and 4 GHz. For x below 0.3, the initial permeability at 100 MHz increases, at higher values of x, its value decreases. Our study shows that magnetic properties of Sr2+ substitution for Ba2+ in Y-type hexaferrite as well as low magnetic loss less than 0.1 in 1 GHz band, indicating the potential application of Ba2−xSrxCo2Fe12O22 samples for RF and antenna devices in ultra high frequency band.

Broadband transverse susceptibility in multiferroic Y-type hexaferrite Ba0.5Sr1.5Co2Fe2O22

“…In Z phase this behaviour is observed at room temperature, but single Z phase formation is still challenging. The magnetoelectric coupling and temperature range in Y-type hexaferrite can be improved by appropriate cation substitution and varying sintering conditions [7][8][9][10]. The crystal structure of Y-type hexaferrite belongs to the R-3m space group with hexagonal structure, and can be obtained with the piling up of S (Me 2 Fe 4 O 8 ) and T (BaFe 8 O 14 ) blocks along the c axis.…”

Low-loss Z-type hexaferrite (Ba3Co2Fe24O41) for GHz antenna applications

“…The μ′ and tan δ μ at different frequencies are given in Table 2. It is noted that the AE Co 2 Z hexaferrite shows the lowest tan δ μ above 1 GHz as compared to the reported lowloss GHz magnetic materials [9][10][11].…”

“…The FOM of the AE Co 2 Z hexaferrite is 174 % and 160 % higher than that of the Co 2 Z hexaferrite [9]. Therefore, the low loss AE Co 2 Z hexaferrite is suitable for GHz antenna applications in the UHF band.…”

“…where ε r is the relative permittivity and μ r is the relative permeability. Thus, high H k hexaferrites have received great attention [4][5][6][7][8][9]. It has been reported that Y-type (Ba [12,13].…”

“…GHz[9]. Moreover, Zn 5 Ni 75 F 20 /polymer (ER 182) composite has μ′ of 3.24 and tan δ μ of 0.063 at 1 GHz[10].…”