A large number of amorphous ribbons based on Finemet have been prepared by rapid quenching on a single copper wheel with linear speed of v = 25-30 m/s. The ribbons are 20-25 μm thick and 6-8 mm wide. All as-cast samples are amorphous. Two criteria producing the colossal magnetocaloric effect (CMCE) in magnetic materials working as magnetic refrigerants are high saturation magnetization and sharp ferromagnetic-paramagnetic phase transition. The Fe-based amorphous ribbons fit these cretia. Thermomagnetic curves as well as isothermal magnetization curves around the Curie temperature of all the studied samples have been determined. The results show that the magnetic entropy change, |ΔS_m|, belongs to a class of materials with CMCE and the |ΔS_m|_max values have been obtained at a moderately low magnetic field change of 1.35 T, moreover |ΔS_m|_max occurred at quite high temperature. © 2006 Elsevier B.V. All rights reserved.

Chau N., The N.D., Hoa N.Q., Huu C.X., Tho N.D., Yu S.-C.

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Từ khóa : Colossal magnetoresistance; Curie temperature; Entropy; Magnetization; Nanocrystalline materials; Phase transitions; Rapid quenching; Amorphous ribbon; Colossal magnetocaloric effect; Isothermal magnetization; Magnetic entropy change; Magnetocaloric effect; Amorphous materials; Amorphous materials; Colossal magnetoresistance; Curie temperature; Entropy; Magnetization; Nanocrystalline materials; Phase transitions; Rapid quenching