表面活性剂调节高矫顽力FePt纳米颗粒的合成

在表面活性剂聚乙烯吡咯烷酮(PVP)存在的体系中,通过NaBH4还原前驱体Fe(acac)3和H2PtCl6·6H2O,制备出了单分散的尺寸在3.0 nm左右的FePt纳米颗粒。XRD和TEM表征结果显示,表面活性剂PVP的用量影响FePt纳米颗粒相变,但对颗粒的尺寸无明显作用。由此推测,PVP对FePt纳米颗粒的相变起"催化"作用,适量的PVP诱导纳米颗粒的相变,可以通过改变表面活性剂的用量来调节FePt纳米颗粒的磁性能,当表面活性剂PVP单体与FePt前驱体的摩尔比(PVP/FePt)为7时,制得的FePt纳米颗粒经过500℃保温30 min热处理后,矫顽力高达5.2 kOe。

Facile synthesis and surfactant regulated high coercivity of FePt nanoparticles

A method of synthesizing high-quality magnetic colloidal dispersions by reduction of Fe(acac)3(acac = acetylacetonate) and H2PtCl6·6H2O in the presence of surfactant poly(N-vinyl-2-pyrrolidone)(PVP) was employed to produce monodisperse FePt nanocrystals with spherical shapes and sizes of 3.0 nm.XRD and TEM results confirmed that the PVP contents had an effect on the transition degree while no significant effect on the particles size.It was consumed that the PVP most probably played the role of the "catalyst",proper amount of PVP induced the easier transformation of the nanocrystals,so the magnetic properties of the nanoparticles can be tuned by varying the surfactant concentrations(the molar ratio of PVP to precursor).The highest coercivity of 5.2 kOe was obtained with the adjusted PVP / FePt molar ratio of 7 when annealed at 500 ℃ for 30 min.