表面活性剂诱导FePt纳米颗粒的形貌控制

Morphological Control of FePt Nanoparticles by Induced Surfactant

选用十二烷基苯磺酸钠(SDBS)作为表面活性剂,采用软液相合成法(soft-solution approach),通过控制表面活性剂十二烷基苯磺酸钠(SDBS)与FePt前驱体的摩尔比(SDBS/FePt),成功制备出了形貌各向异性的FePt纳米颗粒。XRD,TEM表征结果显示:调节摩尔比SDBS/FePt分别为7∶1,9∶1,11∶1时,所制备纳米颗粒均显示化学无序的面心立方(FCC)结构,但颗粒形貌却分别呈现出球形、不规则片状和树枝状结构。振动样品磁强计(VSM)检测结果显示:室温下,所制备颗粒矫顽力显示为零,均表现超顺磁性;惰性气体Ar保护下,500℃保温30 min热处理后,颗粒由超顺磁性转化为铁磁性;当调节摩尔比SDBS/FePt分别为7∶1,9∶1,11∶1时,矫顽力分别显示4489,30429,18457A.m-1;饱和磁化强度也大大改善,分别显示6.65,22.45,11.43 Am2.kg-1。由此可以看出:当调节摩尔比SDBS/FePt为9∶1时,磁能积相对最大。FePt纳米颗粒的磁性能是颗粒尺寸、形貌、组分、结晶性、结构等因素综合作用的结果,推测该结果主要与FePt纳米颗粒的各向异性形貌有关。通过改变表面活性剂的用量可以调节纳米颗粒的形貌,从而改善颗粒的磁性能,这为FePt纳米颗粒的形貌控制以及磁性能的调节提供了一条新途径。

FePt nanoparticles with different morphologies were successfully prepared in the presence of surfactant sodium dodecyl benzene sulfonate （SDBS） with the addition of different molar ratio of surfactant SDBS to precursors of FePt （SDBS/FePt） by a soft-solution approach. XRD and TEM characterizations indicated that the as-synthesized particles possessed chemically disordered face centered cubic （FCC） structure. And the morphologies showed spherical, irregular schistose and dendritic structure respectively when changing the molar ratio of SDBS/FePt from 7：1 to 9：1 and 11： 1. VSM resuhs indicated that the as-synthesized nanoparticles showed zero coercivity and possessed paramagnetic behavior at room temperature and transformed into ferromagnetic when annealed at 500℃ for 30 rain under inert gas of Ar. When adjusted the molar ratio of SDBS/FePt from 7：1 to 9：1 and 11： 1, the coercivity was 4489, 30429, 18457 A.m-1 respectively, and the saturation magnetization Ms changed from 6.65,22.45 to 11.43 Am2 .kg-1. The magnetic energy product showed the largest at SDBS/FePt = 9：1. It could be inferred that the result of differences in nanoparticle morphology although the magnetic property of nanoparticles was the result of the comprehensive effect of nanoparticle size, morphology, component, crystallinity and structure. The morphology and magnetic properties of FePt nanoparticles were controlled by changing the content of surfactant and provided a new way to the morphology and magnetic properties control of FePt nanoparticles.