| In the past several decades, thin films of Fe-N alloys and compoundshave been widely studied. They are excellent materials due to theirvariety of structural and high corrosion/wear resistance and goodmechanical properties. Recently, ferromagnetic iron nitride compounds,such asα--FeB16BNB2B,γ--FeB4BN andε-FeB3BN, have attracted considerableattention by virtue of their excellent magnetic properties. In particular,among the different phases,α--FeB16BNB2B phase is the most importantcompound. It was reported by Kim and Takahashi in 1972 that the newmagnetic material ofα--FeB16BNB2 Bcompound displays a high saturationmagnetization (Ms) of 2.78T (297emu/g), which is larger than that ofFeB0.7BCoB0.3B (2.45T). Besides theα--FeB16BNB2B compound,γ--FeB4BN is anotherimportant magnetic phase, which has a good resistance to corrosion thanthat ofα-Fe. Moreover theγ--FeB4BN phase is chemically more stable thantheα--FeB16BNB2B phase.In this study, Fe-N films and Cu-doped Fe-N films grown by dcmagnetron sputtering are investigated systemically. The conclusions aresummarized as follows:1 an amorphous or/and nanocrystallineε-FeB3BN (111) phase wassynthesized when substrate temperature is RT. As substrate temperatureis 250 PPC, the film will be composed ofγ--FeB4BN single phase which hasclear diffraction peaks. 2 For Fe-N film deposited at RT, which reveals that several particlesdistribute homogeneously. However, for Fe-N film deposited at 250 P-PC,it can be observed that the film surface are composed of regulartriangular particles.3 The saturation magnetization (Ms) and coercivity (Hc) for Fe-Nfilm as-deposited at RT is about 160.36 emu/g and 122 Oe. The values ofMs and Hc for Fe-N film as-deposited at 250℃are 188 emu/g and 150Oe. The difference for Ms can be ascribed to the presence of FeB4BN phasein Fe-N film as-deposited at 250℃, and the difference for Hc is due tothe factors of stress and grains size.4 As annealing temperature increased, grains tend to grow up forFe-N film deposited at RT. As the annealing temperature is raised up to500 PoPC, the peak fromα-Fe (110) appears, which implies that theγ--FeB4BNphase partially decomposes to the more stable phase ofα-Fe after Natoms are released. However, for the film deposited at 250℃, the grainssize will keep almost constant at different annealing temperature becauseof the present of FeB8BN phase.5 Fe-N and Cu-doped Fe-N films were prepared on Si (100)substrates by facing-targets magnetron sputtering. The broad diffractionpeaks (corresponding to FeB3BN (111)) indicates that an amorphous or/andnanocrystalline phase may be formed.6 the coercivity decreased from 122 to 8 Oe, which can be attributedto the formation of nanocrystalline clusters which is due to Cu wasintroduced into Fe-N film. 7 During the heat treatment, the grains size for Fe-Cu-N film arelarger than that for Fe-N film. Therefore, the doping of Cu can improvethe grains grow up in Fe-N film8 As annealing temperature increase to 500 P-PC, no peak fromα-Fephase appears, meaning that FeB4BN is sill stable even anneal at 500 P-PCdue to the doping of Cu into Fe-N film. Therefore, the doping of Cu canimprove the thermal stability of the Fe-N film9 The weak doping of Cu into Fe-N film has no obvious influenceon the chemical bonding states in Fe-N filmIn summary, iron nitride film and Cu-doped iron nitride film wereseposited by dc magnetron sputtering using an Ar/N2 gas mixture. Thestructure, surface morphology and magnetic property of the films wereinvestigated using X-ray diffraction (XRD), transmission electronmicroscopy (TEM), scanning electron microscopy (SEM), and vibratingsample magnetometer (VSM). The deposited conditions were optimized,and the soft magnetic properties and thermal stability for the obtainedsamples were explored.
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