二硫化钨及硼化钨的合成与表征

发布时间：2018-06-18 05:20

本文选题：二硫化钨 + 化学气相沉积　；参考：《吉林大学》2017年硕士论文

【摘要】：过渡族金属钨的化合物在工业生产、科学研究等方面有着重要应用:二硫化钨为半导体材料,近年来人们发现,当二硫化钨由体材料转变为单层材料时,其带隙会由间接带隙转变为直接带隙并具有柔性等特点,因此在薄膜器件、光电器件等领域拥有巨大的应用潜力;硼化钨系列化合物具有优越的机械性能和电学性能,比如硬度高、耐高温、化学惰性好和电阻率低等优点,在机械加工、极端条件下电极制备等领域有着重要的应用;两种钨化合物的合成、表征和性能研究成为近年来超硬、半导体和光电材料的研究热点课题,引起人们的广泛关注。本论文针对两种钨化合物研究中存在的问题开展了如下研究工作:(1)单层二硫化钨的制备和表征;(2)硼化钨及其相关固溶体的合成以及形成机制的研究。(1)过渡金属硫属化物(TMDC)单层材料,具有1-2 e V的可调直接带隙,类石墨烯的晶体结构,因此基于该系列的材料可以组装成性能优良的平面薄膜晶体管、发光晶体管、光探测器、太阳能电池等器件。其中大部分的研究集中在Mo S_2的制备与应用,相比而言WS_2的研究较少。单层WS_2具有1.9 e V的直接带隙,具有较高的迁移率,可以制备为高开关比的场效应管、高响应度的异质结光探测器等器件。为了能够在科研、半导体领域有所应用,制备高质量大面积的WS_2材料无疑是研究的重点也是基础。目前,人们利用机械剥离、锂离子插入等方法进行WS_2单层材料的制备,但这些方法存在着晶体面积小、层数不可控的缺点。因此,寻找高质量、层数可控和大面积生长WS_2的方法和技术成为WS_2研究中的关键问题。化学气相沉积法是一种简单的薄膜制备方法,具备大面积、高质量、可控生长的优点,已经成功用于制备大面积、高质量单层Mo S_2材料。因此,本论文中以WO3为钨源、S粉为硫源,蓝宝石为衬底,利用低压化学气相沉积技术,开展制备WS_2二维材料制备的研究工作,并利用扫描电镜、拉曼光谱进行结构表征。研究结果表明:WO3的量和生长温度对WS_2晶体维度和晶体质量有较大的影响。750°C时,1 mg的WO3作为原料时,易合成出单层WS_2;WS_2晶体层数随着WO3量的增加而增加;当WO3达到5 mg时,生长的WS_2晶体为花朵形状的三维材料。在700°C时,所晶体在衬底表秒分布较为稀疏,升高至800°C时,较为密集,且多为多层材料。我们确定了适合生长单层WS_2材料的实验条件,为单层WS_2的进一步科研应用打下基础。(2)硼化钨系列化合物一直作为在极端环境下最有发展潜质的材料之一:WB具有导电、耐腐蚀、耐高温等特性,可以作为极端环境下的电极使用;W_2B5具有较高的稳定性,可以用于制作复合材料,以提高材料的耐腐蚀性。WB4具有较高的硬度且在高温下同样稳定,因此可以作为金刚石的代替材料制作各类切割工具。为了使WB和W_2B5更具应用价值,提高WB和W_2B5的硬度和导电性成为了研究的热点。因此,我们考虑到使用碳作为掺杂材料,用以提高硼化钨的性能。本论文选用B13C2和W粉分别作为B、C、W源,采用高能机械球磨和后热处理方法进行了碳掺杂硼化钨的制备,通过XRD等表征手段研究了钨硼碳的晶体结构。研究表明:通过高能球磨的方法,可以制备W-B-C非晶合金。在900-1200°C真空氛围中,对球磨后的样品退火处理后。我们推断在900-950°C下退火球磨后的混合物中,有W(B,C)和W_2B(C)两种固溶体生成。为了证明推断,我们利用第一性原理计算证明了WB(C)和W_2B(C)的形成能低于WB和W_2B的形成能,与推断一致。在1200°C下退火处理球磨的样品后,有WB和W_2B5生成。我们通过分析计算,阐明了W_2B(C)和WB(C)固溶体的形成机制,以及硼钨摩尔比和退火温度对硼钨化合物相变的影响。
[Abstract]:The compounds of transition metal tungsten have important applications in industrial production and scientific research. Two tungsten sulfide is a semiconductor material. In recent years, it has been found that when two tungsten sulfide is transformed from body material to single layer material, the band gap will change from indirect band gap to direct band gap and has flexibility, so in film devices and photoelectric devices Such fields have great potential for application, and tungsten borate series have excellent mechanical and electrical properties, such as high hardness, high temperature resistance, good chemical inertness and low resistivity, and have important applications in the fields of mechanical processing, extreme conditions electrode preparation, and the synthesis, characterization and properties of two tungsten compounds. In recent years, the hot topics of super hard, semiconductor and photoelectric materials have attracted wide attention. The following research work has been carried out on the problems in the study of two kinds of tungsten compounds: (1) the preparation and characterization of single layer two tungsten sulfide; (2) the synthesis and formation mechanism of tungsten borate and its related solid solution. (1) transition gold A single layer of sulfur genus (TMDC), with 1-2 e V adjustable direct bandgap and crystal structure of graphene, so based on this series of materials can be assembled into excellent planar thin film transistors, luminescent transistors, photodetectors, solar cells and other devices. Most of these studies are focused on the preparation and application of Mo S_2. WS_2 has less research. Single layer WS_2 has direct band gap of 1.9 e V and has high mobility. It can be prepared as a field effect tube with high switching ratio, high responsiveness heterojunction detector and other devices. In order to be able to be applied in the field of scientific research and semiconductor, preparation of high quality and large area of WS_2 material is undoubtedly the focus of the research. At present, people have made use of mechanical peeling and lithium ion insertion to prepare WS_2 monolayer, but these methods have the shortcomings of small crystal area and uncontrollable number of layers. Therefore, the key problem in WS_2 research is to find high quality, layer number and large area growth of WS_2. Chemical vapor deposition is one of the key problems. A simple thin film preparation method has the advantages of large area, high quality and controllable growth. It has been successfully used in the preparation of large area and high quality single layer Mo S_2 materials. Therefore, in this paper, the research work on Preparation of WS_2 two-dimensional material by WO3 as the tungsten source, S powder as the sulfur source, sapphire as substrate and low pressure chemical vapor deposition technology has been developed. The results show that the amount of WO3 and the growth temperature have a great influence on the dimension of WS_2 crystal and the crystal quality of the.750 degree C. When the 1 mg WO3 is the raw material, the single layer WS_2 is easily synthesized; the WS_2 crystal number increases with the increase of WO3; when WO3 reaches 5 mg, the growing WS_2 crystal is the flower. The three-dimensional material of shape. At 700 C, the crystal is relatively sparse in substrate surface second, and is more dense and multi layer material when it is raised to 800 degree C. We have determined the experimental conditions suitable for the growth of single layer WS_2 material, and lay the foundation for further research and application of single layer WS_2. (2) tungsten borate series have always been in the extreme environment. One of the most potential materials for development: WB has the characteristics of conductive, corrosion resistant, high temperature resistance and so on. It can be used as electrode in extreme environment. W_2B5 has high stability and can be used to make composite materials to improve the corrosion resistance of material.WB4 with high hardness and stable at high temperature, so it can be used as a substitute for diamond. Making all kinds of cutting tools for materials. In order to make WB and W_2B5 more valuable, improving the hardness and conductivity of WB and W_2B5 has become the hot spot of research. Therefore, we consider the use of carbon as a dopant to improve the properties of tungsten boride. This paper uses B13C2 and W powder as B, C, W, high energy mechanical ball milling and post heat. The preparation of tungsten boron boron carbide was prepared by means of carbon doping. The crystal structure of tungsten boron carbon was studied by means of XRD and other characterizations. The study shows that W-B-C amorphous alloy can be prepared by high energy ball milling. In the vacuum atmosphere of 900-1200 degree C, after the annealing of the samples after ball milling, we infer that the mixture after the 900-950 degree C is removed from the mixture of fireball. In order to prove inference, we have proved that the formation energy of WB (C) and W_2B (C) formation energy of WB (C) and W_2B (C) is lower than that of WB and W_2B. In order to prove the inference, we have proved that the formation energy of WB (C) and W_2B (C) is lower than WB and W_2B. After annealing for the samples of ball milling under 1200 degrees C, there are W and solid solutions. The formation mechanism, and the effect of boron tungsten molar ratio and annealing temperature on the phase transition of boron tungsten compounds are discussed.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304

【相似文献】