硅化钛薄膜的制备及其在离子溶液中的双电层电容行为研究

发布时间：2018-05-26 20:45

本文选题：TiSi_2薄膜 + 表面结构　；参考：《浙江大学》2014年硕士论文

【摘要】：由于人口的快速增长和工业化步伐的不断加快,水污染变得越来越严重。污水中一般含有酸、碱、氧化剂,氯化物、氨、氟化物、硝基化合物以及铜、镉、汞、砷等化合物。为了人们的健康,需要更多,更方便的能够实时监测污水中离子浓度的装置,以监测水质是否被污染。双电层电容是通过在电极表面吸附电解质离子来储能的,其在低电解液浓度时的电容值随电解液浓度的增大而增大,有望被应用于污水的实时监测。硅化物薄膜具有低电阻,高的热稳定性和化学稳定性,低的表面逸出功,硅化钛与硅工艺能很好的匹配,因此是一种很好的电极材料。考虑到不同制备条件下制备得到的薄膜表面结构有很大差别。另一方面,双电层电容的电容值不仅与电极的孔隙率有关,还与孔尺寸、孔的拓扑学特性,电解液中离子尺寸等都相关。因而研究不同薄膜制备条件与薄膜结构的关系,不同电解质离子在不同硅化钛薄膜电极双电层电容器中的表现,对提高材料的应用性能,对控制和制备高性能器件将具有非常重要的科学意义和应用价值。本文通过APCVD法在玻璃基板上制备了不同沉积温度,不同硅钛比例的TiSi2薄膜,并通过XRD,SEM,AFM研究了其结晶性和表面结构,通过循环伏安测试研究了其双电层电容特性,并分析了薄膜的表面结构,电解液浓度和电解质对其双电层电容特性和循环伏安曲线形态的影响,并建立了它们之间的理论关系。研究表明,不同硅钛比例和沉积温度下,TiSi2薄膜的结晶性和表面结构分别受到吉布斯自由能和晶体成核与长大的影响。可通过调节硅钛比例,沉积温度获得具有不同表面结构的TiSi2薄膜,要获得低堆积密度,大粗糙度的TiSi2薄膜时,应控制硅钛比为2,沉积温度为6800C和730℃。硅化钛薄膜,纳米线均具有较好的双电层电容特性,其循环伏安曲线呈准矩形。TiSi2薄膜的双电层比电容值与薄膜的堆积密度呈负相关关系,与薄膜表面粗糙高度呈正相关关系。可通过调节硅钛比例,沉积温度获得具有不同比电容的TiSi2薄膜,要获得比电容值大的硅化钛薄膜电极,应控制硅钛比为2,沉积温度为680℃和730℃。实际双电层电容体系中因存在串联电阻,循环伏安曲线偏离标准的矩形。随着串联电阻的增大,曲线偏离矩形的程度增大。受薄膜表面精细结构的影响,串联电阻并非定值,其随电压变化符合下列关系式：R=R_1+[R_2-(KV)~2]=R_0-(KV)~2 这最终导致了大电压处的电流峰的出现,电流峰随着K的增大,凡的减小而增强。电流峰仅在电压到达一定值时出现,且随电压扫描速率的增大而增大。随着电解液浓度的增大,TiSi2薄膜的电容值先线性增大,后达到饱和值后保持不变。成功制得了比电容值达320μF/cm2的TiSi2薄膜,是同样测试条件下ITO薄膜的比电容的22倍。硅化钛纳米线电极的比电容可达1308.7μF/cm2,是ITO薄膜的90倍。TiSi2薄膜在0.05mol/L的Na2SO4溶液中的比电容值就可以达到其在去离子水中的24倍。其在Na2SO4溶液中的饱和比电容是去离子水中的59倍,表现出在污水监测方面极好的应用前景。
[Abstract]:Water pollution is becoming more and more serious because of the rapid growth of population and the accelerating pace of industrialization. The sewage usually contains acids, bases, oxidizers, chlorides, ammonia, fluoride, nitro compounds, and copper, cadmium, mercury, and arsenic compounds. For people's health, more and more convenient devices can be used to monitor the concentration of ions in the sewage in real time. To monitor whether the water quality is polluted or not, the double layer capacitance is used to store the energy by adsorbing electrolyte ions on the surface of the electrode. The capacitance value increases with the increase of the electrolyte concentration in the low electrolyte concentration. It is expected to be applied to real-time monitoring of sewage.
Silicide films have low resistance, high thermal stability and chemical stability, low surface escape work, and titanium silicide can match well with silicon technology. Therefore, it is a good electrode material. Considering that the surface structure of the films prepared under different preparation conditions is very different. On the other hand, the capacitance value of the double layer capacitance is not only with the electricity. The relationship between the pore size, the topological properties of the pores, the ion size in the electrolyte and so on. Therefore, the relationship between the preparation conditions of different films and the structure of the film, the performance of different electrolyte ions in the double layer capacitor of different titanium silicide film electrodes, the improvement of the application performance of the materials, and the control and preparation of the high performance of the materials are also studied. Devices will have very important scientific significance and application value.
In this paper, TiSi2 films with different deposition temperatures and different silicon and titanium ratios were prepared on the glass substrate by APCVD method. The crystallinity and surface structure of the films were studied by XRD, SEM and AFM. The characteristics of the double layer capacitance were studied by cyclic voltammetry. The surface structure of the films, the electrolyte concentration and the electrolyte to the double layer capacitance were analyzed. The relationship between sex and cyclic voltammetry curves was established, and the theoretical relationship between them was established.
The results show that the crystallization and surface structure of TiSi2 films are affected by the free energy of Gibbs and the nucleation and growth of crystal under different Si and Ti ratio and deposition temperature. The TiSi2 films with different surface structures can be obtained by adjusting the proportion of silicon and titanium and at the deposition temperature. To obtain the TiSi2 thin films with low bulk density and large roughness, it should be controlled. The ratio of Si to Ti is 2, and the deposition temperature is 6800C and 730 C.
Titanium silicide films and nanowires have good double layer capacitance characteristics. The cyclic voltammetry curves of the quasi rectangular.TiSi2 film have a negative correlation with the bulk density of the thin films, and have a positive correlation with the surface roughness of the thin films. By adjusting the ratio of silicon and titanium to the deposition temperature, the TiSi2 has a different specific capacitance. To obtain the titanium silicide thin film electrode with larger specific capacitance, the silicon titanium ratio should be controlled at 2, and the deposition temperature is 680 and 730 C.
Due to the existence of series resistance in the actual double layer capacitance system, the cyclic voltammetry curve deviates from the standard rectangle. With the increase of the series resistance, the curve deviates from the rectangle. The series resistance is not a fixed value influenced by the fine structure of the film surface. The variation of the series resistance according to the voltage is in accordance with the following relation: R=R_1+[R_2- (KV) ~2]=R_0- (KV) ~2
This eventually leads to the emergence of the current peak at large voltage. The current peak increases with the increase of K, and the current peak appears only when the voltage reaches a certain value, and increases with the increase of the voltage scanning rate.
With the increase of electrolyte concentration, the capacitance value of TiSi2 film increases first and then remains unchanged after reaching the saturation value. The TiSi2 thin film with a specific capacitance of 320 mu F/cm2 is successfully prepared, which is 22 times the specific capacitance of the ITO film under the same test conditions. The specific capacitance of the titanium silicide nanowire electrode can reach 1308.7 mu F/cm2, and the 90 times.TiSi2 thin of the ITO film. The specific capacitance of the membrane in the Na2SO4 solution of 0.05mol/L can reach 24 times that of the deionized water. Its saturation specific capacitance in the Na2SO4 solution is 59 times that of the deionized water, showing an excellent application prospect in the field of sewage monitoring.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB383.2

【参考文献】