【作者】 王鹏飞；

【导师】 阮永丰；

【作者基本信息】 天津大学 ， 材料物理与化学， 2013， 博士

【摘要】 SiC具有优良的抗辐照性，作为宽带隙半导体材料，可用于制备抗辐照电子器件和辐照探测器，作为结构功能材料，SiC陶瓷和复合材料在聚变堆面向等离子体元件的制备方面具有巨大的应用潜力。这些产品在使用过程中因受到载能粒子的辐照而产生大量的缺陷，进而导致各种性能退化。所以充分认识辐照缺陷的形成机制、微观构型及其对宏观物性的影响非常重要。本文利用拉曼光谱和X射线衍射研究了1.72×1019和1.67×1020n/cm2中子辐照的6H-SiC，详细结果如下：1.检测到与Si-Si振动有关的189、275、437和539cm-1峰，与Si-C振动有关的610、657和712cm-1峰，和与C-C振动有关的1420cm-1峰。大注量辐照后，还检测到1357和1603cm-1峰，它们分别属于无序石墨的A1g和E2g振动模。这些散射峰证明辐照导致SiC中形成了Si原子团、sp2/sp3C团和石墨团。2.辐照导致FTO2/6和FLO0/6光学峰在低波数区域出现了拖尾，这是辐照缺陷引起的声子限制效应。辐照导致FTO2/6和FLO0/6峰向低波数方向发生了不同程度的偏移，造成FLO0/6-FTO2/6劈裂减小，这主要归因于VC和VSi缺陷。3.对辐照缺陷进行热稳定性分析，发现Si原子团、sp2/sp3C团和石墨团分别在1100、1000和800℃退火后消失。退火过程中还检测到575cm-1峰，它在800℃退火后首次出现，1400℃退火后消失，应该属于CSiVC缺陷的Si-C振动。4.石墨团的产生强烈地依赖于辐照注量和故意掺杂的N杂质。本质上，诱导石墨团产生的是N聚集体而不是NC施主。在中子辐照过程中，N聚集体可以形成CSi(NC)2缔合体，它具有sp2C=C原子对，可起到石墨晶核的作用。5.辐照前预退火处理导致石墨团的浓度显著地降低，经过1000℃预退火处理的样品几乎不能产生石墨团。主要原因是：预退火处理导致N聚集体发生分解，辐照过程不能再形成石墨晶核sp2C=C原子对。6. X射线衍射法和透射电子显微镜分析法揭示，经过这两种注量辐照的SiC含有的缺陷类型主要是点缺陷、缺陷团和非晶区。7.利用X射线衍射法分析了（006）衍射峰的退火回复规律，发现衍射FWHM（半高宽）回复过程分为三个阶段：200-800℃、800-1400℃和1400-1600℃。8.利用（006）衍射峰FWHM的退火回复规律，开发出辐照SiC晶体测温技术。通过具体试验证实，这种测温技术可以对工作在900-1600℃范围内的部件进行最高温的测定，相对误差在3%以内。更多还原

【Abstract】 Silicon carbide (SiC) is a superior irradiation-resistance material. It can be usedfor fabricating the irradiation resistance electronic devices and irradiation detectors.The SiC-based ceramics and composites are the potential materials for the fusionplasma-facing components. During the application in severe irradiation environment,the irradiation induced defects will lead directly to the deterioration of performances.It is essential to recognize the formation mechanism and microstructure of irradiationdefects and the effect of defects on the macroscopic properties. The confocalmicro-Raman spectroscopy and X-ray diffraction were employed to investigate the6H-SiC neutron irradiated up to1.72×1019and1.67×1020n/cm2. The details are asfollows:1. The Si-Si related peaks at189,275,437, and539cm-1, the Si-C related peaksat610,657, and712cm-1, and C-C related peak at1420cm-1are recorded. Afterhigh-fluence neutron irradiation, the peaks at1357and1603cm-1are also measured.They agree well with A1gand E2gin disordered graphite. These scattering peaksindicate that irradiation leads to the production of Si clusters, sp2/sp3C clusters andgraphite clusters.2. Irradiation results in the appearance of the low-frequency tails of the FTO2/6and FLO0/6optical peaks, which is phonon confinement effect. Irradiation defects alsodiminish unequally the frequency of the FTO2/6and FLO0/6peaks, leading to thereduction of FLO0/6-FTO2/6splitting. The annealing evolution demonstrates that theVCand VSiare responsible mainly for the reduction of the FLO0/6-FTO2/6splitting.3. Annealing experiments reflect that the Si clusters, sp2/sp3C clusters andgraphite clusters are removed after1100,1000and800oC annealing treatments,respectively. In addition, an interesting peak at575cm-1is measured during annealingtreatment. It emerges initially after annealing at800oC and vanishes at1400oC. Thisevolution indicates the575cm-1originates from the Si-C vibration of CSiVCcomplex.4. The formation of graphite clusters depends strongly on the neutron fluenceand intentionally incorporated N impurity. Essentially, the formation originates fromN aggregation but not from NCdonor. During neutron irradiation, N aggregation cantransform into CSi(NC)2complex, which contains the sp2C=C pair. The sp2C=C paircan act as the graphite nucleus.5. Pre-irradiation annealing treatment can decrease the concentration of graphite clusters. After the pre-irradiation annealing treatment at1000oC, the graphite clustersbecome almost undetectable because the N aggregation dissociates into isolated Natoms and then there is no pproduction of sp2C=C pair in SiC during the subsequentirradiation.6. The X-ray diffraction measurement and transmission electron microscopyanalysis indicate that there are mainly points, clusters, and amorphous regions in thesamples neutron irradiated up to the two fluences.7. The X-ray diffraction was employed to analyze the annealing recovery of theFWHM (full with at the half maximum) of the (006) diffraction peak, which showsthe200-800oC,800-1400oC, and1400-1600oC recovery stages.8. Based on the above mentioned recovery stages, the neutron irradiated SiC wasemployed to determine the maximum temperature of the parts running in the range of900-1600°C. The application test results demonstrated that the technique possesses aless than3%of the relative temperature errors.更多还原