【作者】 王春旭；

【导师】 李晓天； 李楠；

【作者基本信息】 吉林大学 ， 材料物理与化学， 2012， 硕士

【摘要】 本论文主要采用水热方法结合煅烧处理制备微/纳米结构的氧化钇纳米线和亚微米纤维，并采用XRD，SEM，TEM，TG-DTA，N₂吸附，IR等测试手段对样品进行了详细的表征和分析。具体内容如下：通过水热反应制备了Y₄O（OH）₉（NO₃）纳米线，经进一步煅烧分解得到氧化钇纳米线。Y₂O₃纳米线的直径范围为20-35nm，长度为0.6-1μm。纳米线呈现多孔结构，孔的尺寸为5-15nm。实验发现提高水热反应温度有利于提高纳米线的长径比和尺寸的均一性，增大pH值有利于形成尺寸更小的纳米线。通过水热反应制备了Y（OH）_xCl_3-x·yH₂O亚微米纤维，进一步煅烧分解得到氧化钇亚微米纤维。氧化钇纤维的直径为100-300nm，长度可达数十微米。实验结果表明提高水热反应温度，减小pH值有利于形成更加完好的纤维形貌。氧化钇纤维表现出优异的高温稳定性，经过高温煅烧后其形貌仍没有改变。更多还原

【Abstract】 Yttrium oxide （Y₂O₃） is one of the most important rare-earth compounds andhas been extensively applied to optics, functional ceramics, optoelectronics, catalyticreactions and high-efficient additives for functional composite materials. With respectto the physical properties, yttrium oxide has a high melting temperature （Tm=2430°C）, which is higher than that of a number of other well-known oxides, such asalumina, zirconia, YAG, and spinel. Yttrium oxide normally exists as a cubic phaseand is stable up to melting point without phase transformation. Many methods, suchas solid-state method, sol–gel processing, gas-phase condensation, precipitation,hydrothermal synthesis, and so on, have been developed to prepare yttrium oxide withdifferent morphology. Compared with other methods，hydrothermal synthesis iswidely accepted as a better and simple method to prepare materials with controlledmorphology and particle size. So in this paper we used hydrothermal synthesis toprepare yttrium oxide micro/nanometer materials.Here, we successfully synthesized yttrium oxide nanowires in nitric acid system.First，Y₄O（OH）₉（NO₃） nanowires were synthesized through a facile hydrothermalreaction, followed by a subsequent heat treatment obtained yttrium oxide nanowires.The diameter of the nanowires ranged from20to35nm, while the length was0.6-2 μm, with aspect ratio of20-50. XRD and TG-DTA charaterizations show that theobtained Y₂O₃is pure phase. TEM and N₂adsorption characterizations show theobtained yttrium oxide nanowires were porous, with pore size of5-15nm. It has beenshowed that the hydrothermal temperature and pH value play crucial roles indetermining morphology of the products. It is found that increasing reactiontemperature would increase the aspect ratio of nanowires as well as improving thedistributing uniformity on diameters. Smaller nanowires could be obtained byincreasing pH value. By controlled the hydrothermal reaction temperature and pHvalue, the optimal experimental reaction conditions of formation the best morphologyfor the nanowires have been obtained:200°C for the hydrothermal temperature,13for pH value. The pores were originated from the decomposition of the hydrothermalprecursor Y₄O（OH）₉（NO₃） during the heat treatment to form yttrium oxide. Yttriumoxide formed porous structure in thermodynamics after calcining perhaps due toforming a more stable structure in the process of heat treatment. And the porous Y₂O₃nanowires will be of interest in optics and catalysis fields.Yttrium oxide ceramic fibers are attractive as reinforcements for high-temperaturematerials due to the combination of high strength and excellent high-temperaturestability in air. We successfully synthesized yttrium oxide sub-micrometer sized fibersin hydrochloric acid system in this paper. In this experimentmt, yttrium oxidesub-micrometer sized fibers have been synthesized via hydrothermal reaction andsubsequent thermal treatment using yttrium compound for Y（OH）₃（NO₃）_3-x·yH₂Osub-micrometer sized fibers as precursor. The fiber diameter ranged from100to300nm, while the length was up to tens of microns. The products before and after thethermal treatment were characterized by powder X-ray diffractions （XRD）, scanningelectron microscopy （SEM）, ion chromatograph analysis, and thermogravimetry anddifferential thermal analysis （TG-DTA）. It was found that the chemical composition,structure, and morphology of the products were closely related to the pH value ofreaction solution, and fibrous products could be obtained at pH9.5-10.25. Theexperiment results show that hydrothermal temperature, pH value and yttriumconcentration play important roles in determining particle size of the products. It is found that increasing reaction temperature and decreasing pH value, would obtainebetter morphology of the fibers. By controlled the hydrothermal reaction temperatureand pH value, the optimal experimental reaction conditions of formation the bestmorphology for the fibers have been obtained:200°C for the hydrothermaltemperature,9.5for pH value. These oxide fibers exhibited outstandinghigh-temperature stability, which maintained their morphology at temperature up to1400°C. Consequently, these fibers would be promising materials for refractoryapplications, such as refractory insulation and high temperature gas filtration.更多还原