Nanocrystallization behaviour and optimized magnetoimpedance effect in FeZrBNbCu alloys

Abstract

The work aims at understanding the changes in magnetic properties and the magnetoimpedance (MI) effect for the Fe 84.5 Zr 4 B 8.5 Nb 2 Cu 1 (FZBNC) nanocrystalline alloys with the annealing temperature (T a) from the microstructure point of view. The as-quenched FZBNC ribbons were annealed in a vacuum condition at selected temperatures for 20 min. The microstructures of the specimens were examined by the x-ray diffraction technique. The bcc α-Fe phase is identified from the XRD patterns. The mean grain size of the α-Fe phase (D 1) at different annealing temperatures (T a) was estimated using Scherrer's equation. The results show that D 1 for the sample annealed at 575 • C is about 20 nm, which is the smallest value among all the samples. Measurements on the MI effect reveal that the FZBNC ribbon annealed at 575 • C exhibits the most drastic MI ratio of 756% at 600 kHz accompanied by the field sensitivity of 108% Oe −1 , while a large MI effect is not observed in the sample annealed at other temperatures. The origin of the excellent MI effect is investigated in this paper.

Enhanced magnetoimpedance and field sensitivity in microstructure controlled FeSiCuNbB ribbons

“…15,16 The obtained coercivity (H c ) of FIN-1 sample in the heattreated state of 500 C is greater than the as-quenched state, which is a consequence of stress relaxation induced earlier during the rapid solidification technique. The decrease in H c value for T a > 500 C of both these alloys can be attributed to the nucleation of soft magnetic Fe 3 Si phase.…”

Thickness dependence of crystalline state in FeZrNbCuB thin films obtained by sputter deposition

“…Within this framework, in this paper we have prepared Fe 84 Nb 3.5 Zr 3.5 B 8 Cu 1 (at.%) thin films; this composition is well studied in amorphous and nanocrystalline ribbons because of its high magnetic permeability, low coercivity and high saturation magnetization [25][26][27][28][29][30][31][32]. In our films, the observed dependence of the saturation magnetization on film thickness is interpreted in terms of the development of a ␣-Fe crystalline phase at the early stages of growth, followed by the formation of the amorphous alloy.…”

The test circuit construction and noise suppression for giant magneto-impedance sensor

“…The GMI effect is the phenomenon that exhibits certain magnetic materials consisting of a large variation of the electrical impedance as a function of the applied magnetic field [1] Recently, great interest has been paid to the GMI effect in soft magnetic materials [2][3][4][5][6] . Circuit designs for magnetic field sensor based on GMI effect named GMI magnetic sensor have been proposed [7,8] .…”