【作者】 苏玉荣；

【导师】 谢二庆；

【作者基本信息】 兰州大学 ， 凝聚态物理， 2012， 博士

【摘要】 Zr02和Hf02纳米材料因其独特的物理化学性质在电学、光学以及耐温材料等诸多领域有广泛的应用前景。利用物理和化学的方法制备各种低维纳米材料,进而实现对其结构、形貌及物性的调控,对于深入研究纳米材料的形成过程以及生长机理,从而实现对纳米材料的结构设计以及功能调控具有重要的意义。本论文在Zr02和Hf02低维纳米材料的合成、形成机制以及物性等方面进行了系统的研究。创新性地建立了一种制备纳米带的简易方法。采用自行搭制的静电纺丝装置制备了Zr02和Hf02纳米线、纳米带。系统地研究了电纺丝的基本控制参量如溶液浓度、电压、固化距离、环境温度对纳米带形貌的影响。实验发现,通过控制溶液的浓度可以得到高宽比可控的纳米带。此外,高温环境对纳米带的形成十分有利,在环境温度为70℃时能得到厚度为5nm的超薄纳米带。在此基础上,提出了纳米带的生长机理：相分离效应是纳米带形成的主要因素,而溶剂的快速挥发对纳米带的形成至关重要。采用此项技术,实现了其他材料(ZnO、SnO2、PAN)纳米带的可控制备。初步探讨了稀土掺杂HfO2纳米带在发光器件中的潜在应用。为了增强纳米颗粒的发光效率,在稀土掺杂的ZrO2纳米颗粒表面包覆惰性和活性外壳。研究了壳层厚度和外壳掺杂对纳米材料结构和发光性能的影响,从实验和理论上揭示了包覆纳米材料发光强度提高的机制。发现活性外壳同时具有保护内核中发光离子和吸收紫外光并将能量传递给内核中的发光离子两方面的作用。HfO2薄膜作为一种重要的高介电常数材料在MOS型器件中有潜在的应用。本论文采用反应溅射法在Si衬底上制备了Hf02薄膜。研究了薄膜的生长参数和后处理对薄膜结构和电学性能的影响。得到了性能最优异的Hf02薄膜的制备参数。同时对各种缺陷的形成机理以及缺陷对薄膜电学性能的影响也进行了研究。更多还原

【Abstract】 Owing to unique physical and chemical properties, nanostructured zirconium oxide and hafnium oxide have exhibited promising applications in electrics, optics, temperature-resistant and other fields. Preparing low-dimensional nanostructures by phycal and chemical methods and investigating their general formation mechanism may be a solution to the precise control of their structure, morphology and properties. In this dissertation, systematic explorations have been carried out on synsthetic strategies of zirconium oxide and hafnium oxide, their formation mechanisms and properties.A simple synthetic method for nanobelts has been developed. ZrO2and HfO2nanowires, nanobelts were prepared in homemade electrospinning setup. The effects of electrospinning parameters such as solution concentration, the voltage and the distance between the cathode and the anode, ambient temperature on the morphology of nanobelts were systematic investigated. We found that the aspect ratio of nanobelts could be adjusted by controlling the polymer solution concentration. In addition, elevated ambient temperature is favorable to the formation of the nanobelts and ultra-thin nanobelts (-5nm) could be obtained at70℃. On this basis, the growth mechanism of nanobelts was discussed. It was found that phase separation effect is the main factor in the formation process of nanobelts and the rapid evaporation of solvent played an important role. Several polymer solutions with different solvent have been electrospun and corresponding nanobelts were fabricated by this method. The potential application of rare-earth-doped HfO2nanobelts in the light emitting devices was explored.To enhance the intensity of luminescence in nanoparticles, rare earth doped ZrO2nanoparticles coated with inert and active shells have been synthesized. The effects of the shell thickness and rare earth doped active shell on the luminescence of the nanoparticles have been demonstrated. The active-shell serves two purposes:one is to protect the luminescing rare earth ions from the non-radiative decay and the other is to transfer UV absorbed radiation to the luminescing core.HfO2has emerged as the most promising high dielectric for MOS devices. In this dissertation, HfO2thin films were prepared by reactive sputtering at silicon substrate. The impact of the deposition parameters and post-treatment on the structure and electrical property of HfO2films was analysed to explore the best preparation condition of HfO2film. Moreover, the formation mechanism of various defects was indicated and the defects effect on the electrical properties of the films was suggested.更多还原