纳米γ-Ni-Fe合金的磁电阻

Magnetoresistance of nanocrystalline γ-Ni-Fe alloy

用机械球磨Fe_2O_3-NiO氧化物和氢气还原原位合金化法,制备出纳米γ-Ni-xFe(x=20％～39％,质量分数)合金,并通过XRD、TEM、SEM、BET等方法研究了材料的微观结构与制备条件的关系。结果表明:当氢气还原原位合金化的温度为600～700℃时,合金化完全,Ni-Fe合金的晶粒尺寸为15～55nm,平均颗粒尺寸小于100nm;在30K至室温范围内,块体纳米Ni-Fe合金的各向异性磁电阻率(MR)随温度的降低线性地增加。室温MR=0.98％;在50K,MR值达8.7％,高磁电阻的原因可能是纳米Ni-Fe合金强烈的磁相关界面散射。

Nanometer-sized γ-Ni-xFe (x=20%-39%, mass fraction) alloy were successfully prepared by hydrogen reduction and in-situ alloying of ball milled Fe2O3-NiO powders. The relationship between the microstructure and synthesis conditions was investigated by using XRD, TEM, SEM and BET. The results showed that the grain size was about 15-55 nm at in-situ alloying temperature from 600 to 700°C, and there were few agglomerates with average sizes below 100 nm; The temperature dependence of magnetoresistance (MR) for nano-Ni-Fe alloy was studied in the temperature range from room temperature to 30 K. The MR increased linearly when temperature decreased. The value of MR is 0.98% at room temperature and reaches 8.7% at 50 K. The results may be explained in terms of intensive interface scattering of nano-Ni-Fe alloy in relation to magnetism.