硅化铁（锰）纳米材料的制备、表征及形成机理
发布时间：2019-01-27 23:03
【摘要】：过渡金属硅化物,是一类难熔的金属间化合物,因其独特的物理和化学性质而被成功应用于互补金属氧化物半导体元件、薄膜涂层、块体结构组件、电热元件、热电材料和光伏材料等领域。其纳米材料更是表现出特别的电学、光学、磁学和热电等性能,甚至在催化领域也具有潜在的应用价值。然而,冶金方法或物理方法等传统的制备方法无法满足过渡金属硅化物纳米材料的制备。因此,寻找简单可控而普遍适用的制备方法对于过渡金属硅化物纳米材料的广泛应用具有十分重要的意义。基于以上目的,本论文分别采用金属有机化学气相沉积(MOCVD)法、热解法和球磨法,制备二氧化硅负载的硅化铁和硅化锰纳米材料以及硅化铁和三氧化二铝纳米复合材料,并对其形成机理和磁学性能进行了研究。本论文的主要研究内容和结果如下： (1)以金属有机化合物Fe(CO)4(SiCl3)2为单源前体、以二氧化硅为载体,采用MOCVD法在400℃和常压下制备得到了二氧化硅负载的FeSi纳米粒子。以Fe3(CO)12和SiHCl3为原料,在无水无氧的条件下合成了以反式结构为主的Fe(CO)4(SiCl3)2。表征结果显示,所得FeSi纳米粒子的相态单一,平均粒径约为10.8nm。推测得到了MOCVD过程中FeSi纳米粒子的形成机理：吸附在二氧化硅载体上的Fe(CO)4(SiCl3)2分子优先丢失一个SiCl4分子生成Fe=SiCl2(CO)4,然后在氢气的促进作用下,先后脱除羰基基团、断裂Si-Cl键,最终形成二氧化硅负载的FeSi. (2)以金属有机化合物Mn(CO)5(SiCl3)为单源前体、以二氧化硅为载体,采用MOCVD法在400℃和常压下制备得到了二氧化硅负载的MnSi纳米粒子。以Mn2(CO)10和SiHCl3为原料,在无水无氧的条件下合成了Mn(CO)5(SiCl3)。表征结果显示,所得MnSi纳米粒子的尺寸约为5-6nm,且均匀分散在二氧化硅载体上。利用原位FTIR分析推测得到了MnSi纳米粒子的形成机理：吸附在二氧化硅载体上的Mn(CO)5(SiCl3)分子在氢气的促进作用下,先后脱除羰基基团、断裂Si-Cl键,最终形成二氧化硅负载的MnSi。 (3)以聚二甲基硅烷为硅源、二茂铁为铁源,采用热解法制备得到了二氧化硅负载的Fe3Si纳米粒子。表征结果显示,600℃下热解所得的Fe3Si纳米粒子的平均粒径约为7.6nm,且高度分散在二氧化硅上；随着热解温度升高至800℃,所得纳米粒子的平均粒径增大至16.2nm,同时有新相Fe5Si3生成；所得纳米粒子暴露在空气中其表面形成一薄层Fe203和SiOx氧化层。57Fe穆斯堡尔谱图、M-H曲线以及FC和ZFC曲线表明热解所得的硅化铁纳米粒子在室温下表现出超顺磁性,在低温下表现出铁磁性。特别地,硅化铁纳米粒子尺寸的减小对其饱和磁化强度、居里温度和阻挡温度等磁学性能产生明显的影响。 (4)以四氧化三铁、硅粉和铝粉为原料,采用球磨法并结合氢气气氛高温处理制备得到了Fe3Si-Al2O3纳米复合材料。表征结果显示,随着原料中硅粉比例的增加,所得纳米粒子的晶相发生由Fe到Fe3Si再到Fe3Si、FeSi和Fe5Si3混合相的转变,其中较小粒子的平均粒径约为20nm,由于高温团聚作用,较大粒子的平均粒径约为60nm,而且所得纳米粒子的表面存在少量无定形的硅和二氧化硅。磁滞回线表明不同硅粉比例下所得的铁和硅化铁纳米复合材料在室温下表现出铁磁性。
[Abstract]:The transition metal silicide is a kind of refractory intermetallic compound, which is successfully used in the fields of complementary metal oxide semiconductor element, thin film coating, bulk structural component, electric heating element, thermoelectric material and photovoltaic material due to its unique physical and chemical properties. The nano material also has the characteristics of special electrical, optical, magnetic and pyroelectric properties, and has potential application value even in the catalysis field. However, the conventional preparation method of the metallurgical method or the physical method cannot meet the preparation of the transition metal silicide nano material. Therefore, it is of great significance for the wide application of transition metal silicide nano-materials to find a simple and controllable preparation method. Based on the above objects, the present paper adopts the metal organic chemical vapor deposition (MOCVD) method, the thermal solution and the ball-milling method to prepare the silicon-based iron and the silicon-silicide nano-material with the silicon dioxide loading, and the silicon-based iron and the aluminum oxide nano-composite material. The formation mechanism and magnetic properties were studied. The main contents and results of this paper are as follows: (1) The Fe (CO) 4 (SiCl3) 2 as a single-source precursor was used as the carrier, and the FeSi nanoparticles loaded with silicon dioxide were prepared by the MOCVD method at 400 鈩，
本文编号：2416788
[Abstract]:The transition metal silicide is a kind of refractory intermetallic compound, which is successfully used in the fields of complementary metal oxide semiconductor element, thin film coating, bulk structural component, electric heating element, thermoelectric material and photovoltaic material due to its unique physical and chemical properties. The nano material also has the characteristics of special electrical, optical, magnetic and pyroelectric properties, and has potential application value even in the catalysis field. However, the conventional preparation method of the metallurgical method or the physical method cannot meet the preparation of the transition metal silicide nano material. Therefore, it is of great significance for the wide application of transition metal silicide nano-materials to find a simple and controllable preparation method. Based on the above objects, the present paper adopts the metal organic chemical vapor deposition (MOCVD) method, the thermal solution and the ball-milling method to prepare the silicon-based iron and the silicon-silicide nano-material with the silicon dioxide loading, and the silicon-based iron and the aluminum oxide nano-composite material. The formation mechanism and magnetic properties were studied. The main contents and results of this paper are as follows: (1) The Fe (CO) 4 (SiCl3) 2 as a single-source precursor was used as the carrier, and the FeSi nanoparticles loaded with silicon dioxide were prepared by the MOCVD method at 400 鈩，
本文编号：2416788
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