Abstract:

Nanocrystalline γ′-Fe₄N thin films were synthesized on single crystal Si(100) substrate by facing target magnetron sputtering and were heat-treated in vacuum at different temperatures of 300, 400, 500, 600, 700 and 800 ℃ in order to investigate their thermal stability. The structure, morphology and magnetic properties were characterized using X-ray diffraction(XRD), scanning electron microscopy(SEM) and vibrating sample magnetometer(VSM), respectively. The results indicated that Fe₈N capsule layer was formed at the interface of γ′-Fe₄N grain between the heat-treating temperature of 300 and 500 ℃. At heat-treating temperature of 600 ℃, the Fe₈N phase layer tended to decompose to the more stable phase α-Fe. The complete phase transformation from nanocrystalline γ′-Fe₄N phase to α-Fe phase occurred at 700 ℃. The obvious changes of the structure and soft ferromagnetic properties were not found under the temperature of 600 ℃.

Key words: γ′-Fe4N thin film; Structure; Magnetic property; Thermal stability