FePt纳米颗粒的制备与表征

发布时间：2018-05-30 10:37

  本文选题：FePt + 磁性纳米颗粒　； 参考：《沈阳师范大学》2015年硕士论文

【摘要】：社会的发展需要磁性材料向高性能,多功能方向发展,而纳米磁性材料能够有更好的磁性能及块体纳米磁性材料所没有的其他功能。面心立方(FCT)相FePt具有高的磁晶各向异性,超顺磁临界尺寸为2-4nm,化学稳定性好,因而能够作为很好的纳米磁性材料。现今制备FePt纳米材料主要分两大类：物理方法制备FePt纳米薄膜和化学合成FePt纳米颗粒。但是制备面心四方(FCT) FePt纳米材料的最大问题是材料进行退火热处理过程中会发生团聚和烧结现象。为此,物理制备方法制备纳米FePt时主要有两种策略,一种是通过降低退火温度,如通过掺杂Ag, Cu, Au等,另一种是减少退火时间,如快速退火,激光退火等。另外FePt纳米薄膜可以在强磁场和合适的基底取向生长。但是物理方法制备出的FePt有序度不高,小于0.7.而化学合成FePt纳米颗粒的主要方法有两种,一种是化学合成面心四方(FCC)相纳米颗粒再盐浴退火,另一种是在FCC-FePt纳米颗粒外包覆一层高熔点物质来阻止退火时的烧结和团聚,如MgO, SiO2等。化学合成制备FCT FePt的优点是颗粒的大小,形状都是能够很好的控制的,有序度高,可大于0.8。但化学制备FCT-FePt步骤稍多。本文针对化学合成法制备FePt纳米颗粒的实验步骤多,合成出的纳米颗粒还需要高温退火会导致颗粒团聚现象,采用一步固相烧结法直接制备FCT相FePt纳米颗粒：直接用乙酰丙酮铁和乙酰丙酮铂与氯化钠(或氯化钾)球磨混合均匀,然后直接高温煅烧制备FCT的FePt纳米颗粒。通过对此方法制备出的FePt纳米颗粒进行VSM、XRD、TEM等手段进行磁性能、晶体结构、微观形貌与结构等表征分析。论文的主要研究内容和结果如下：1.通过调节Fe、Pt前驱体的摩尔量,当Fe、Pt元素在1：3和3：1时,制备出的纳米颗粒的矫顽力很低,XRD分析表征制备出的分别是FePt3和Fe3Pt;发现Fe、Pt比例在1：1时制备出的FePt纳米颗粒有较好的磁性能,制备出的颗粒是FCT结构。2.固定Fe、Pt前驱体比例为1：1,通过调节NaCl的量,对比在不同比例的NaCl与Fe、Pt前驱体混合后制备出的FePt纳米颗粒的磁性能和微观形貌与结构分析,表明当NaCl与Fe、Pt前驱体的比例在不超过2000：1时,可以制备出FCT结构的FePt纳米颗粒,且随着氯化钠比例的降低,颗粒平均尺寸逐渐增加,矫顽力逐渐增加,当氯化钠与FePt的摩尔比在300：1时,矫顽力达到22KOe。3.通过对比不同温度下煅烧时制备出的颗粒磁性能,煅烧温度在750℃时,磁性能最高,随着煅烧温度的降低,矫顽力也逐渐降低,颗粒平均尺寸也有所降低,并且在低于400℃煅烧时仍制备出FCT相的FePt纳米颗粒,其矫顽力在5K0e。本论文中的一步固相法烧结制备FePt纳米颗粒,操作步骤少,不需要先化学合成FCC相FePt纳米颗粒,能够直接制备出FCT相FePt纳米颗粒；与核壳结构相比(SiO2,MgO外层保护)用盐可以有效阻止FePt烧结时的晶粒过分长大,不会降低FePt的性能或去除保护层时会破坏FePt的完整性。
[Abstract]:The development of the society requires magnetic materials to be high and multi-functional, and nano magnetic materials can have better magnetic properties and other functions. The FCT phase FePt has high magnetocrystalline anisotropy, the superparamagnetic critical size is 2-4nm, and the chemical stability is good, so it can be used as a good one. FePt nanomaterials are mainly divided into two major categories: the preparation of FePt nanomaterials by physical methods and the chemical synthesis of FePt nanoparticles. But the biggest problem of preparing the FCT FePt nanomaterials is the agglomeration and sintering of the materials during the annealing process. There are two main strategies for m FePt. One is by reducing the annealing temperature, such as by doping Ag, Cu, Au and so on. The other is to reduce the annealing time, such as fast annealing, laser annealing, etc., and the FePt nanomilt can grow in strong magnetic field and suitable substrate orientation. But the FePt order of the physical method is not high, less than 0.7. and chemistry. There are two main methods for the synthesis of FePt nanoparticles, one is the chemical synthesis of FCC phase nano particles in the salt bath annealing, the other is that the FCC-FePt nanoparticles are coated with a high melting point material to prevent the sintering and agglomeration, such as MgO, SiO2, etc.. The advantage of the chemical synthesis of FCT FePt is the size and shape of the particles. It is able to be well controlled, with high order degree, more than 0.8., but more than 0.8., but there are more steps in preparing FCT-FePt. In this paper, there are many experimental steps to prepare FePt nanoparticles by chemical synthesis, and the synthesized nanoparticles also need high temperature annealing to lead to the agglomeration of particles. A one-step solid phase sintering method is used to direct the preparation of FCT phase FePt nanoparticles directly. FCT FePt nanoparticles were prepared by ball milling of acetacetone iron and acetacetone (or acetylacetone) with sodium chloride (or potassium chloride). The magnetic properties, crystal structure, micromorphology and structure of the FePt nanoparticles prepared by this method were analyzed by means of VSM, XRD, TEM and other means. The results are as follows: 1. by adjusting the molar amount of Fe, Pt precursor, when Fe and Pt are in 1:3 and 3:1, the coercive force of the prepared nanoparticles is very low, and FePt3 and Fe3Pt are prepared by XRD analysis, and Fe and Pt ratio are found to have good magnetic properties. The ratio of Fe and Pt precursor is 1:1. By adjusting the amount of NaCl, the magnetic properties and microstructure and microstructure of FePt nanoparticles prepared by NaCl and Fe, Pt precursor are compared. The results show that when the proportion of NaCl and Fe and Pt precursor is not more than 2000:1, the nanoparticles can be prepared. With the reduction of sodium chloride ratio, the average size of the particles increases gradually and the coercivity increases gradually. When the molar ratio of sodium chloride to FePt is at 300:1, the coercive force reaches 22KOe.3. by comparing the magnetic properties of the particles prepared at different temperatures. The magnetic energy is highest when the calcining temperature is 750, and the coercive force is also driven by the calcining temperature. The average size of the particles is also reduced, and the FePt nanoparticles of FCT phase are still prepared at less than 400 C. The coercive force is prepared by one step solid phase sintering in the 5K0e. paper. The operation steps are less, and the FCC phase FePt nanometers are not needed to be synthesized first, and the FCT phase FePt nanoparticles can be prepared directly. Compared with the core shell structure (SiO2, MgO outer protection), the salt can effectively prevent the grain from excessive growth when FePt is sintered, which will not reduce the performance of FePt or destroy the integrity of the FePt when the protection layer is removed.
【学位授予单位】：沈阳师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

【参考文献】

相关期刊论文 前2条

1 张鑫;李鑫钢;姜斌;;四氧化三铁纳米粒子合成及表征[J];化学工业与工程;2006年01期

2 ;DNA and RNA sensor[J];Science in China(Series B:Chemistry);2005年01期

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