自旋转换纳米材料的合成及性能研究

发布时间：2018-05-16 06:30

本文选题：自旋转换 + 亚铁三唑　；参考：《江南大学》2017年硕士论文

【摘要】：自旋转换化合物作为磁性分子材料的前沿领域,由于其可逆的高低自旋态转换的性质而在显示器、传感器、记忆材料及分子开关等领域具有潜在应用。亚铁三唑化合物是自旋转换材料的典型代表,因其在纳米尺寸下仍能够保持良好的自旋转换性能,而引起人们的广泛兴趣。本课题旨在通过将自旋转换纳米颗粒与氧化石墨烯(GO)基底复合、金属中心替换、一维银纳米线(AgNWs)复合及与自旋交叉材料复合,合成了四类自旋转换纳米复合材料,并研究了该材料在结构上的特点对其自旋交叉特性的影响:1.为了探索氧化石墨烯基底对自旋交叉配合物的形貌及自旋转换特性的影响,采用了一种简单原位自组装的方式将亚铁三唑类纳米采用化学负载的方式负载到氧化石墨烯的表面,得到了自旋转换/氧化石墨烯纳米材料,扫描与透射图显示立方体状的[Fe(Htrz)2(trz)](BF4)(FeH)纳米颗粒生长在石墨烯的上下表面,且随着反应时间的增长,其尺寸和数量均有所增加。磁性测试表明随着自组装时间的的延长Fe H/GO的转变温度向高温区移动,且摩尔磁化率-T曲线由平缓变得较为尖锐,这可能是由于FeH纳米颗粒的尺寸、形貌及其与GO之间的相互作用的影响所致。2.为了探究不同金属离子对自旋交叉材料的磁性产生的影响,将亚铁三唑类自旋转换化合物FeH纳米颗粒的金属中心Fe(II)用金属中心Cu(Ⅱ)替换,得到了[Fe(Htrz)2(trz)](BF4)@[Cu(Htrz)2(trz)](BF4)(Fe H@Cu H)核壳纳米材料。同时,采用微乳液法将金属中心Fe(II)用金属中心Cu(Ⅱ)部分替换,得到[Fe_xCu_(1-x)(Htrz)2(trz)](BF4)(Fe_xCu_(1-x))纳米颗粒。SEM图表明随着Cu(Ⅱ)金属中心所占的比例的增加Fe_xCu_(1-x)纳米颗粒的长径比也在增大;而相较于长棒状且表面光滑的FeH纳米颗粒,FeH@Cu H表面变得粗糙,且尺寸有所增加;TEM图可以直观地观察到核壳结构的形成。磁性分析表明Fe_xCu_(1-x)纳米表现出渐变型不可逆的自旋转换行为,这可能是由于两种金属中心在其一维链状结构中随机排列,导致其协同性降低所致。FeH@Cu H纳米表现为突跃型可逆的自旋转换行为,发生自旋交叉时的温度有上升的趋势,且低温区表现为反铁磁性。3.为了将自旋转换纳米材料与导电性能优异的银纳米线(AgNWs)结合,利用银纳米线表面裸露的银金属中心可与Htrz配位的性质,采用原位生长的方式合成具有导电性能的AgNWs@FeH及AgNWs@[Fe(NH2trz)3](BF4)2(AgNWs@FeN)自旋转换纳米材料。扫描电镜图表征了随着原位生长时间的增长Ag NWs表面的FeH由颗粒状逐渐生长成长条状,扫描与透射电镜图表征了呈球状FeN颗粒在AgNWs表面的成核和生长;磁性分析表明Ag NWs@FeH表现为突跃型可逆的自旋交叉现象,且其摩尔磁化率-T曲线变得平缓,发生自旋交叉时的温度有上升的趋势,且磁滞回线宽度增加;而AgNWs@FeN则始终处于氋自旋态,未表现出自旋交叉行为。这可能是由于纳米颗粒形貌尺寸、核壳结构、固态稀释效应及结合水含量等影响导致的。4.为了将两种转变温度不同的自旋转换化合物的性质组合到同一种材料中,利用异质外延的性质,采用向FeH纳米分散液中逐滴加入FeN前驱体溶液的方法,合成了FeH@FeN核壳纳米材料,SEM图表征了随着Fe N的前驱体溶液加入量的增加,Fe N壳在Fe H核表面由最初的颗粒状逐渐生长为一层致密的壳,直观地证明核壳结构的形成;磁性分析表明核壳纳米表现为滞回型自旋转换行为,且其转变温度对应于FeH的自旋转变温度,而Fe N壳中的Fe(II)在所测的温度范围内处于氋自旋状态,并未发生自旋转换现象,这可能是由于Fe N壳自身性质及其小的尺寸所致。
[Abstract]:As the frontiers of magnetic molecular materials, spin conversion compounds have potential applications in the fields of display, sensors, memory materials and molecular switches due to their reversible high and low spin state transitions. The ferrous three azole is a typical representative of the spin conversion material, which can still maintain a good self in the nanometer size. The purpose of this study is to synthesize four kinds of spin conversion nanocomposites by compounding spin converted nanoparticles and graphene oxide (GO) substrates, substitution of metal center, one dimensional silver nanowire (AgNWs) composite and spin cross materials, and the structural characteristics of the material are studied. The influence of the spin cross characteristics: 1. in order to explore the influence of the graphene oxide substrate on the morphology and spin conversion properties of the spin cross complexes, a simple in situ self-assembly was used to load the iron three azoles on the surface of graphene oxide with a chemical load, and the spin conversion / graphite oxide was obtained. Nanomaterials, scanning and transmission diagrams show that cubic [Fe (Htrz) 2 (Trz)] (BF4) (BF4) (FeH) nanoparticles grow on the upper and lower surfaces of graphene, and as the reaction time increases, the size and quantity of the nanoparticles are increased. The magnetic test shows that with the time of self assembly, the transition temperature of Fe H/GO moves to the high temperature zone, and the molar magnetization is shown. The rate -T curve becomes more sharp from the gentle, which may be due to the influence of the size, morphology and interaction between the FeH nanoparticles and the interaction with GO to explore the influence of different metal ions on the magnetic production of the spin cross materials, and the metal center Fe (II) of the ferrous three azole type spin conversion compound FeH nanoparticles. Central Cu (Htrz) 2 (Trz)] (BF4) @[Cu (Htrz) 2 (Trz)] (BF4) (BF4) (Fe H@Cu H) nuclear shell nanomaterials were obtained. Meanwhile, the microemulsion method was used to replace the metal center of metal center (2). The ratio of the length to diameter of Fe_xCu_ (1-x) nanoparticles is also increasing, while the surface of FeH@Cu H becomes rough and the size increases, compared with the long rod like and smooth FeH nanoparticles. The TEM diagram can observe the formation of the shell structure intuitively. The magnetic analysis shows that the Fe_xCu_ (1-x) nanometers exhibit the irreversible irreversible spin conversion behavior of the Fe_xCu_ (1-x) nanometers. This may be due to the random arrangement of two metal centers in one of its one-dimensional chain structures, resulting in the reduction of.FeH@Cu H nanoparticles as a result of a jump type and reversible spin conversion. The temperature of the spin crossing is rising, and the low temperature region is antiferromagnetic.3. in order to make the spin converted nanomaterial and electrical conductivity. Excellent silver nanowires (AgNWs) binding, using the properties of the silver metal center exposed on the silver nanowire surface with the Htrz coordination, can be used to synthesize the conductive AgNWs@FeH and AgNWs@[Fe (NH2trz) 3] (BF4) 2 (AgNWs@FeN) spin conversion nanoscale by in situ growth. The scanning electron microscopy diagram characterizing the increase Ag with the growth time in situ. The FeH on the surface of NWs is growing and growing in a granular form. The scanning and transmission electron microscopy shows the nucleation and growth of spherical FeN particles on the surface of AgNWs. The magnetic analysis shows that Ag NWs@FeH is a jump type and reversible spin cross phenomenon, and the -T curve of the molar susceptibility to -T becomes slow and the temperature of the spin cross is rising. The width of the hysteresis loop is increased, while the AgNWs@FeN is always in the spin state and does not exhibit the spin cross behavior. This may be due to the effect of.4. on the properties of the two kinds of spin conversion compounds, due to the size of the nanoparticles, the core and shell structure, the solid state dilution effect and the combined water content. In the material, using the properties of heteroepitaxy, the FeH@FeN nuclear shell nanomaterials are synthesized by adding FeN precursor solution to the FeH nano dispersions. The SEM diagram shows that the Fe N shell grows from the initial granular to a dense shell along the Fe H nuclear surface with the increase of the Fe N precursor solution. The magnetic analysis shows that the nuclear shell nanoscale shows the hysteresis type spin conversion behavior, and the transition temperature corresponds to the spin transition temperature of FeH, while the Fe (II) in the Fe N shell is in the spin state within the measured temperature range, and does not have the spin conversion image, which may be due to the properties of the Fe N shell itself and its small ruler. It is the result of inch.

【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1

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