PVP对FePt纳米颗粒磁性能的影响

Effect of Poly(N-vinyl-2-pyrrolidone) on Magnetic Properties of FePt Nanoparticles

以乙酰丙酮铁(Fe(acac)3)和氯铂酸(H2PtCl6·6H2O)作为Fe源和Pt源,硼氢化钠(NaBH4)作为还原剂,PVP作为表面活性剂,通过化学还原法制备出单分散的FePt纳米颗粒,研究PVP对FePt纳米颗粒磁性能的影响。通过X射线衍射(XRD)仪,透射电子显微镜(TEM)和振动样品磁强计(VSM)对纳米颗粒进行表征。结果表明:PVP修饰的FePt纳米颗粒为面心立方(fcc)结构,形状近似球形且分散性良好,矫顽力为零,呈超顺磁性。当PVP与Fe(acac)3的比例为7:1时,经600℃热处理保温30min,FePt纳米颗粒从无序的fcc结构转变为有序的fct结构,矫顽力最大,可达5460A·m-1。

With Fe（acac）3 as Fe3＋ source and H2 PtCl 6·6H2O as Pt4＋ source, FePt nanoparticles were prepared via chemical reduction process using NaBH 4 and poly （N-vinyl-2-pyrrolidone） （PVP） as reductant and surfactant, respectively. The effect of PVP on magnetic properties of FePt nanoparticles was investigated. The as-prepared FePt nanoparticles were characterized by X-ray powder diffraction （XRD）, transmission electronmicroscopy （TEM） and vibrating sample magnetometer （VSM）. The results show that PVP modified FePt nanoparticles are of face-centered-cubic （fcc） structure, which are spherical shapes with good mono-dispersibility. The particles display superparamagnetic as the coercivity is zero. For the FePt nanoparticles with PVP/Fe（acac）3=7：1, the structure transforms from face-centered-cubic （fcc） to face-centered-tetragonal （fct） after the sample is annealed at 600 °C for 30 min in argon atmosphere, with its coercivity reaching as high as 5400 A·m-1 .