氢在二氧化钛中的行为研究

发布时间：2018-03-15 06:32

本文选题：二氧化钛　切入点：氢　出处：《北京科技大学》2015年博士论文　论文类型：学位论文

【摘要】：氢在氧化物材料中的研究工作目前还很少,一般认为氢很少与氧化物材料发生反应。传统上,氢对材料作用的研究起始于冶炼、酸洗、电镀和焊接等过程中引起的金属材料的氢致塑性损伤(氢脆)以及氢致裂纹及断裂等危害,从而开启了人们对氢在金属材料中的影响研究。而近期的研究表明,氢对一些半导体氧化物材料的电学、磁学、光学等性能都能起到非常显著的影响。尤其针对二氧化钛材料的研究,有越来越多的研究表明氢对二氧化钛的光催化性能、电学性能等均有显著的影响。本论文以金红石型二氧化钛材料为研究对象,对氢在二氧化钛材料中的行为规律进行研究。研究内容主要分为四个部分：氢的侵入、存在、扩散和改性。结合实验和第一性原理计算,得出以下几个结论： 1.研究了两种不同的氢处理方式(高温气相氢处理和电化学氢处理)下二氧化钛材料中的氢原子存在形式。通过实验,尤其是通过第一性原理计算从实验和理论两个方面研究了氢在二氧化钛中的具体形式。在高温气相氢处理中,氢原子倾向于处在氧空位的位置；在电化学氢处理中,氢原子倾向于处于氧原子的八面体间隙位置中。处于氧空位上的氢原子在晶体中是得电子的,并呈电负性；而处于间隙位置的氢原子是失电子的,呈现电正性,并与最近的氧原子形成OH键。同时,对比二氧化钛的结构变化,发现氧空位对二氧化钛晶格参数的影响最大,其次是间隙氢原子,影响最小的是氧空位上的氢原子。 2.通过对不同温度和在不同退火时间的氢处理的二氧化钛样品,以及在不同温度下的氘气的渗透率来对氢在二氧化钛中的扩散行为进行研究。研究发现随着氢处理时间的增加,二氧化钛样品中的氢含量也随着增加。当经过50小时的氢处理样品中的氢原子达到饱和后,氢含量趋于稳定。氢处理温度在200到1000摄氏度的温度范围内,温度越高,二氧化钛中的氢含量也越大。同时,氢在二氧化钛陶瓷和单晶材料中的扩散也存在差异,在温度较低时,二氧化钛陶瓷中的氢含量较高。而在温度较高时,二氧化钛单晶中的氢含量较高。通过氢在二氧化钛薄膜中的渗透速率还计算出了氢在二氧化钛薄膜材料的渗透能。 3.二氧化钛的氢致改性研究主要从三个方面：电学、光学和亲疏水性。对电学性能的研究,发现通过氢处理能够让二氧化钛的电导增加,使材料从半导体向导体转变；对光学性能的研究,发现氢处理能够调控二氧化钛的能带结构,使材料的带隙减小并对可见光波段的吸收增强；对亲疏水性的研究,发现氢处理能增强二氧化钛表面的疏水性。通过以上对氢在二氧化钛材料的行为研究,能够进一步扩展二氧化钛材料在环境保护、新能源等领域的开发和应用。同时也为氢在其他氧化物材料中的行为规律的研究提供实验和理论参考,为其它氧化物材料的开发应用提供帮助。
[Abstract]:Research work on hydrogen in oxide materials is still rare, and it is generally believed that hydrogen rarely reacts with oxide materials. Traditionally, the study of hydrogen's effect on materials began with smelting, pickling and pickling. Hydrogen induced plastic damage (hydrogen embrittlement) and hydrogen induced cracks and fractures in metal materials caused by electroplating and welding have opened up the study of the influence of hydrogen on metal materials. Hydrogen has a significant effect on the electrical, magnetic and optical properties of some semiconductor oxide materials. In this thesis, the behavior of hydrogen in titanium dioxide materials is studied. The research contents are divided into four parts: the invasion of hydrogen, the existence of hydrogen, the existence of hydrogen, and so on. Diffusion and modification. Combined with experiments and first-principles calculations, the following conclusions are drawn:. 1. The existence forms of hydrogen atoms in titanium dioxide materials under two different hydrogen treatment methods (high temperature gas phase hydrogen treatment and electrochemical hydrogen treatment) have been studied. In particular, the specific forms of hydrogen in titanium dioxide have been studied from both experimental and theoretical aspects through first-principle calculations. In high temperature gas phase hydrogen treatment, hydrogen atoms tend to be in the position of oxygen vacancy, and in electrochemical hydrogen treatment, Hydrogen atoms tend to be in the octahedron gap of oxygen atoms. Hydrogen atoms in oxygen vacancies are electronegativity in crystals, while hydrogen atoms in the gap position are electron-lost and electronpositive. At the same time, compared with the structural changes of titanium dioxide, it is found that the oxygen vacancy has the greatest influence on the lattice parameters of titanium dioxide, followed by the interstitial hydrogen atom, and the hydrogen atom on the oxygen vacancy is the least. 2. The diffusion behavior of hydrogen in titanium dioxide was studied by the permeability of hydrogen treated at different temperature and annealing time, and deuterium gas at different temperature. It is found that the diffusion behavior of hydrogen in titanium dioxide increases with the increase of hydrogen treatment time. The hydrogen content in the titanium dioxide sample also increases. When the hydrogen atom in the sample reaches saturation after 50 hours of hydrogen treatment, the hydrogen content tends to stabilize. The higher the temperature, the higher the hydrogen treatment temperature is in the range of 200 to 1000 degrees Celsius. At the same time, the diffusion of hydrogen in titanium dioxide ceramics and single crystal materials is also different. At lower temperature, the hydrogen content in titanium dioxide ceramics is higher, but at higher temperature, the content of hydrogen in titanium dioxide ceramics is higher than that in titanium dioxide ceramics. The hydrogen content in titanium dioxide single crystal is high and the permeation energy of hydrogen in titanium dioxide thin film is calculated by the permeation rate of hydrogen in titanium dioxide film. 3. The research of hydrogen induced modification of titanium dioxide is mainly from three aspects: electricity, optics and hydrophobicity. It is found that the conductivity of titanium dioxide can be increased by hydrogen treatment, and the material can be changed from semiconductor to conductor; It is found that hydrogen treatment can regulate the energy band structure of titanium dioxide, decrease the band gap and enhance the absorption of visible light wave band, and the hydrophobicity can enhance the hydrophobicity of titanium dioxide surface. Through the above research on the behavior of hydrogen in titanium dioxide materials, it is possible to further expand the environmental protection of titanium dioxide materials. The development and application of new energy and other fields also provide experimental and theoretical reference for the study of the behavior of hydrogen in other oxide materials, and provide help for the development and application of other oxide materials.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ134.11

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