Magnetic state of Fe at and near the interface between Fe–Al–Si magnetic thin films and Zn–ferrite

Abstract

The magnetic state of Fe atoms at and near the interface between Fe74.3Al9.8Si15.9 sendust magnetic thin films and polycrystalline Zn–ferrite substrates has been examined using conversion electron Mössbauer spectroscopy. The thicknesses of sputtered films are 0.05, 0.08, 0.47, and 1.91 μm, and the annealing conditions are at 500 °C for 1 h. The sendust films/Zn–ferrite interface is very reactive, and the DO3-type ordered structure is not formed near the interface. This is the reason that excellent soft magnetic properties are not obtained for the films with a thickness of less than 0.47 μm. The presence of ferromagnetic Fe atoms with an internal magnetic field of 324 or 330 kOe is confirmed near the interface, indicating the formation of an Fe-rich phase such as Fe94Si6 and diffusions of Al and Si atoms from the sendust films to the interface. The thickness of the Fe-rich phase in the films has been estimated to be approximately 0.42 μm from the value (12.8 kG) of saturation magnetic-flux density for the film with 1.91 μm. It is found that a large part of Fe3+ ions in Zn–ferrite being at the interface is reduced to Fe2+ ions. The redox reaction at the interface has been proposed.

Microstructure and magnetic properties of nanostructured (Fe 0.8 Al 0.2 ) 100–x Si x alloy produced by mechanical alloying

“…Within the Fe-rich region (up to 22 at% Al) the crystalline alloys are in fact disordered solid solutions with bcc crystal structure, where Al (Si) atoms occupy Fe sites [16]. The ternary FeAlSi compounds around the 75:10:15 compositional ratio (Sendust alloy) attracted a remarkable interest in the 90's due to their excellent soft magnetic properties including high magnetic permeability and low coercivity [17,18]. More recently, a renewed curiosity on this ternary system has grown especially related to the modification of the magnetic properties induced by microstructural and compositional changes [19].…”