【作者】 尤静林；

【导师】 徐匡迪； 蒋国昌；

【作者基本信息】 上海大学 ， 钢铁冶金， 2006， 博士

【摘要】 物质微结构研究及其相关科学技术是物理学和材料科学的交叉领域中基础研究与应用研究相结合的新的学科生长点和新材料的源泉。物质微结构研究将揭示不同层次的微结构与性能的相互关系，并在此基础上，按所需特定功能去进行微结构设计，借助于当代先进实验技术获得和改造各种先进材料，并揭示其内涵深刻的物理化学过程和特殊效应。高温状态的物质结构研究，特别是高温熔体的研究已引起包括冶金、地质、晶体生长、光谱学和计算化学等诸多学科的关注和重视，也取得了一些重要进展。本文综述了包括X-ray衍射（散射）、核磁共振谱和拉曼散射光谱等实验方法，以及量子化学、经典力学基础上的分子模拟和耦合计算等理论方法，阐明了相关研究的基本原理和特点，分析和评估了各类方法的优势和欠缺，并以此作为研究方向和研究手段考量的依据。拉曼光谱因其在高温下的应用潜力，确立成为本学位论文的基本实验手段，同时引入量子化学从头计算等方法加以理论阐释。上海大学现代冶金与材料制备重点实验室在原有JY U1000型双光栅单色仪的基础上，配置了Olympus BH-2微区分析用显微镜和Leitz microscopic heating stage 1350型显微热台，探测器为单道扫描，光源采用Ar＋514．5 nm或488．0 nm激发线，实现了高温达1600 K的显微拉曼（micro-Raman）。此外，还运用光谱信号的时间分辨检测技术，激光光源采用铜蒸气或半导体脉冲激光器，实现了可达2023 K温度下的宏观拉曼（macro-Raman）。这两项改造在高温物质（固态和液态）的拉曼光谱测量中，有效地抑制了背景的强烈热辐射，获得了满意的效果。不仅如此，创新性地将增强型电荷耦合探测器（ICCD）与可见脉冲激光同步耦合在JY LabRam HR800型拉曼光谱仪上，实现了累积时间分辨和空间分辨耦合的新一代的高温拉曼光谱技术。硅酸盐是地球上极为丰富的物质，涉及冶金、玻璃、陶瓷和地质岩浆等许多学科领域，其结构和性能及其相互关系一直令人关注，因此，硅酸盐微结构研究具有十分重要的意义。本文总结了前人在硅酸盐微结构方面的研究成果，设计了具有结构代表性的硅酸盐离子簇系列，采用量子化学从头计算优化几何构型和实施了拉曼光谱的计算，同时定义和提出了硅氧四面体应力指数（SIT）的概念，有效地归纳了非桥氧对称伸缩振动频率与SIT的内在关联，沟通了一系列稳定局部结构的电子和几何因素，提升了硅酸盐微结构拉曼光谱表征的特征性和实用性．这些成果能较好地应用于硅酸盐晶体结构和拉曼光谱的诠释；也有利于硅酸盐玻璃拉曼光谱特征的描述，特别是解释了硅酸盐不同微结构单元偏拉曼光谱的不对称性；在引入振动频率的温度系数后，也有利于对硅酸盐熔体拉曼光谱的解读。从实验和理论计算上系统地考察了碱金属系列阳离子对离子簇微结构和其拉曼光谱地影响。结果表明，不同的阳离子对离子簇局部几何结构影响甚微，也没有引起非桥氧对称伸缩振动频率的显著不同，但是却对其拉曼散射截面产生显著的改变。电子结构的计算同时表明，半径较大的阳离子可以提升非桥氧键的共价性成分，从而导致更大的拉曼散射截面。同时，对拉曼光谱中“奇异”现象如相邻Q₃与Q₄间的“邻位增强”效应在电子云结构层次上进行了较好的说明。碱金属和碱土金属硅酸盐晶体的温致变化以及相应玻璃和熔体的光谱研究表明，拉曼光谱具有较好的结构分辨本领以及高温原位观察特性，十分适合于温致相变的研究．硅酸盐熔体的拉曼光谱虽然缺乏较高的信噪比，但却反映了熔体中离子簇宽泛分布的本质。通过对熔体光谱的解谱，可以有助于了解微结构单元温致变化的规律，为沟通硅酸盐结构和性能的关系奠定基础。将自主开发的宏观和显微以及累积时间和空间耦合分辨的高温拉曼光谱新技术应用于多项基础的研究工作，涉及冶金熔渣、晶体生长、玻璃化学、地球化学、功能材料等诸多领域，研究对象包括无机聚合体系（磷酸盐和硼酸盐）、熔盐（硝酸盐和碳酸盐）、陶瓷功能材料、纳米材料和制备以及晶体生长原位检测等。通过对多种物质结构形态，晶体、玻璃和熔体的光谱测量、分析和比较，以及原位观察温致相变过程，可以得出，高温拉曼光谱技术是物质相诊断和结构研究的强有力工具，并为观察物质高温状态和熔体的结构及其变化提供了实验研究的可能和便捷，特别是在材料制备和高温熔体法晶体生长边界层的结构变化研究中更是提供合适的原位实验手段。探索和揭示了高温下物质在分子水平其微观结构随化学组成与温度的变化和规律，以及与物质宏观性质的相互关系，且有力地促进多种新技术和新材料的开发，其中，尤为突出了高温和熔融条件下物质微结构及其拉曼光谱的特点。同时，采用相关的结构和谱学计算方法，并结合其它相关研究手段，诠释了所获得的实验拉曼光谱，深化了对物质微结构基元的认识，为沟通物质微结构和宏观性能的相互关系提供了良好的基础。更多还原

【Abstract】 Micro-structure study and relative science and technology development are new growth of subject and headspring of new materials in basic and applied study among crossed fields of physics and materials sciences. Micro-structure study can discover the relationship between micro-structures of materials and their macro properties. According to this, micro-structure design can be introduced to meet the requirement for realizing and improving specific functions of various materials with the enhancement of advanced experimental techniques, and the physical and chemical processing and special mechanism can be revealed.Study of micro-structure under high temperature, especially for melts, have brought much attention and recognition in the fields of metallurgy, geology, crystal growth, spectroscopy and computational chemistry and have made achievement in the past. In this paper, experimental methods of X-ray diffraction （or scattering）, nuclear magnetic resonance and Raman spectroscopy, as well as theoretical methods of quantum chemistry, molecular simulation and relative coupling methods are reviewed. The rationales and their characteristics of various researching method are introduced, their advantages and deficiencies are also evaluated as consideration for this study. Raman spectroscopy is chosen as predominant experimental method because of its potentials in application under high temperature, while quantum chemistry and other methods being applied for theoretical explanation.High temperature micro-Raman spectrometer （up to 1623 K） is constructed by using Leitz microscopic heating stage and argon ion laser （lines, 514.5 and 488.0 nm） coupled with Olympus BH-2 microscopy and mono channel scanning based on JY U1000 monochromator in Shanghai Enhanced Laboratory of Modern Metallurgy and Material Processing in Shanghai University. High temperature macro-Raman spectrometer （up to 2023 K） is also constructed by using pulsed laser （copper vapor laser or semi-conductor laser） and time resolved detecting technique. With the help of these techniques, dense background thermal radiation can be satisfactorily eliminated in routine Raman spectra recording. Furthermore, a novel high temperature Raman spectroscopic technique combined with accumulated time and space resolved method is realized by coupling intensified charge coupled device （ICCD） with visible pulsed laser.Silicates are most abundant substances on the earth, involved with domains of metallurgy, glass, ceramic and geologic magma, and micro-structure study about silicates is most significantly important. In this paper former efforts of studies on micro-structure of silicates were summarized. A series of typical silicate clusters with characteristic structure are designed, and they are optimized in geometric configuration, and made Raman spectrum simulation by using quantum chemistry ab initio calculation method. A new concept of stress index of silicon-oxygen tetrahedron （SIT） is defined and applied to correlate the vibrational wavenumber of non-bridging oxygen symmetric stretching of silicon-oxygen tetrahedron with the value of SIT. This helps to understand local stabilized micro-structure affected by geometric and electron structure, and strengthens the representation, characteristic and application of Raman spectra of silicate. It demonstrates that various Raman spectra of silicates can be satisfactorily elucidated, especially for the understanding of non-symmetry of partial Raman spectra of primary structure of silicates. It also helps to explain characteristics of silicate melts while temperature coefficient is introduced.Cation effect on micro-structure and its Raman spectrum of silicate cluster is investigated by experimental and theoretical calculation for alkali silicates. It shows that the local micro-structure configuration has little been influenced, the vibrational wavenumber of non-bridging oxygen symmetric stretching of silicon-oxygen tetrahedron has also no distinct deviation, but the cross section of Raman optical active vibration is dramatically affected. Cation with larger radius can enhance the covalent component of non-bridging oxygen bonding which is the key point for increasing Raman optical activity as confirmed by electron structure calculation. Meanwhile, other spectral effects such as neighbor enhancement, which means that Raman optical activity of non-bridging oxygen of primary Q₃ species will be enhanced by neighboring Q₄ species, can also be understood.Temperature dependent Raman spectra of alkali and alkali earth silicate crystals, and Raman spectra of silicate glasses as well as their melts demonstrate that Raman spectra have the advantage of delicate structure resolution and characteristics for high temperature in-situ recording and investigation, especially for the research of temperature dependent structure transformation. Although high temperature Raman spectra of silicate melts have lower signal-noise ratio, it reflects the fact and the nature of multiple cluster species coexisted. Deconvolution of Raman spectra of silicate melts can be used to diagnose micro-structure units and investigate temperature dependent varieties of them, as helps to establish a basement for communicating micro-structure and its property of silicate.Self developed high temperature Raman spectroscopic techniques are also applied to record various materials in the fields of metallurgy, crystal growth, glass chemistry, geology and functional materials, including inorganic polymers （phosphates and borates）, molten salts （nitrates and carbonates）, functional ceramics, nano materials and relative processing, as well as in-situ investigation of crystal growth. It is concluded that high temperature Raman spectroscopy is a powerful tool for phase diagnosis and micro-structure investigation of various materials, and also offer experimental possibility and convenient to penetrate the micro-structure of substances and their melts under high temperature, especially during materials processing such as micro-structure of boundary in crystal growth. Temperature and chemical composition dependent micro-structure deviation and its rule on atom or molecular level can be explored and discovered. Those results vice versa help to develop new manufacture techniques during new materials exploring. With the help of related experimental and calculation method, the obtained experimental Raman spectra are well annotated and elucidated, which deepen one’s knowledge of micro-structure units of substances and establish a good basement to correlate macro-properties with their micro-structures.更多还原