High-frequency absorption properties of gallium weakly doped barium hexaferrites

ABSTRACT

The BaFe_12-xGa_xO₁₉ (x < 1.2) hexaferrites were synthesised by usual ceramics technology. The Bi₂O₃ additive in the amount of 3 wt% was applied. The features of crystal structure and unit cell parameters were refined using powder X-ray diffraction at 300 K. It is shown that with the substitution level increase the parameters of unit cell monotonically decrease. The magnetisation and susceptibility versus temperature and field for these solid solutions were investigated by the vibration magnetometry method. The concentration dependence of the main magnetic parameters is constructed. It is shown that with the substitution level increase the magnetic parameters monotonically decrease. The microwave properties of the samples including the external magnetic bias field are also investigated at 300 K. It is shown that with the increase of Ga³⁺ concentration from x = 0.1 to x = 0.6 the frequency value of natural ferromagnetic resonance (NFR) decreases in the beginning, and at further increase in concentration up to x = 1.2 it increases again. With the increase in Ga³⁺ concentration, the line width of the NFR increases that indicates the increase of frequency range where there is an intensive absorption of electromagnetic radiation (EMR). At the same time, the peak amplitude of the resonant curve changes slightly. The frequency shift of NFR in the external magnetic bias field takes place more intensively for the samples with small Ga³⁺ concentration. It is shown the prospects of use of the Ga-substituted barium hexagonal ferrite as the material effectively absorbing the high-frequency EMR.

KEYWORDS:

• Solid-state reactions
• crystal structure
• magnetic and absorption measurements
• doped hexaferrites

PACs:

• 81.40.Vw
• 61.05.С-
• 77.80.B-

Additional information

Funding

This work was carried out with financial support in part from the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» implemented by a governmental degree dated 16-th of March 2013, No 211 among the leading world scientific and educational centers: grant number P02-2017-2-4 and additionally grant No. К4-2017-041 and No. K3-2018-026. This work was also partially supported by the Ministry of Education and Science of the Russian Federation with Government task in SUSU 4.1346.2017/4.6. Additionally this work was performed using equipment of MIPT Shared Facilities Center and with financial support from the Ministry of Education and Science of the Russian Federation with grant number RFMEFI59417X0014. Present work is also realised with assistance of grants of Belarus republic Foundation for Basic Research (BRFBR) No. F19KOR-003 and No. F19K-027.