二元钾硅酸盐玻璃结构的Raman光谱分析

用带空间分辨和累积时间分辨耦合系统的Raman光谱仪,测定了二元钾硅酸盐K2O·xSiO2玻璃及晶体的Raman光谱,比较并解释了随SiO2含量变化的微结构单元Raman振动模。结果表明:钾硅酸盐玻璃有多种微结构单元共存,并且随二氧化硅含量的增加,微结构逐步由硅氧四面体单体向二聚体、链状、层状和网络状转化。硅氧四面体对称伸缩振动区的主峰不对称性以及展宽主要是由于一系列具有不同微环境下的二级结构的变化造成的。微环境的不同是造成精细微结构单元和光谱表征差异的根本原因。Raman光谱的精细结构反映了微结构单元连接的复杂性,采用二级结构的概念有利于在更深层次和更大的空间范围内来认识硅酸盐玻璃微结构。     

AbxAnxDiy硅酸盐熔体结构及其结晶相的高温Raman光谱研究

运用高温Raman光谱测试技术 ,对共结线附近一系列的AbxAnxDiy 样品进行了升温过程的研究。系统地对比分析了这一系列样品的玻璃 -晶体 -熔体的Raman光谱特征。低温玻璃与高温熔体在结构上虽然很相似 ,但确实存在差别。晶体与玻璃和熔体的特征峰有相似性 ,反映了晶体结构对熔体结构的继承性。晶体Raman峰的强度变化规律与温度和成分关系 ,反映了相图中不同首晶区的结晶过程特点和晶体含量的变化关系。同时 ,通过对高频区的解谱研究了体系中各结构单元的种类及含量与温度的关系     

拉曼光谱在硅酸盐熔体结构研究的应用

硅酸盐在冶金、材料等诸多领域应用非常广泛,硅酸盐熔体的微观结构决定了其物理化学性质,因此,对硅酸盐熔体结构的研究至关重要。拉曼光谱是研究硅酸盐熔体结构的一种有效手段,应用拉曼光谱在常温下测定玻璃态硅酸盐结构和采用高温拉曼光谱技术测定完全熔融状态下硅酸盐结构一直是一个重要的研究方向,并且也取得了很多研究成果。在硅酸盐熔体结构的拉曼谱峰中,400～800cm^-1波数段内反映了[SiO₄]四面体中桥氧的弯曲或伸缩振动,800～1200cm^-1波数段内反映了[SiO₄]四面体中非桥氧的对称伸缩振动,含有其它离子的硅酸盐熔体的拉曼谱峰会因离子属性的不同而改变其位移、半高宽和强度。     

非晶态硅酸盐微观结构的研究进展

总结了目前对非晶态硅酸盐微观结构的认识。综述了硅酸盐的分子动力学模拟技术的最新发展以及Raman光谱研究的最新结果。在简要叙述了其它的实验研究手段的基础上,将Raman光谱与它们进行了简单比较,阐明了Raman光谱在硅酸盐微观结构研究方面的优越性,总结了该研究领域需要进一步研究的内容。     

氧化钆对磷酸钡玻璃微结构影响的热分析及光谱分析

为研究氧化钆对磷酸钡玻璃热性能及微结构的影响,采用熔融-淬火法制备xGd_2O_3-(100-x)(50BaO-50P_2O_5)(x=0,2,4,6,8mol%)系列玻璃,研究了玻璃密度和摩尔体积及热相变特性,并利用X射线衍射(XRD)、扫描电镜(SEM)、红外光谱(FT-IR)、拉曼光谱(Raman)等测试技术对样品的微结构进行了分析。研究结果表明:当x≤6 mol%时,体系易形成透明的均质玻璃,当x=8 mol%时,样品中出现GdPO_4晶相;在玻璃形成范围内,增加Gd_2O_3含量,使玻璃微结构网络更致密,玻璃热稳定性得到改善;FT-IR和Raman光谱表明玻璃微结构主要是Q~2结构单元,有少量Q~0和Q~1结构单元。     

As2S3-PbI2二元系玻璃的形成与结构

运用传统的熔融淬冷技术制备了As2S3-PbI2二元系玻璃样品。通过XRD,TG-DTA,Raman光谱等实验手段研究了该二元系玻璃的形成范围、热性能与结构。实验结果表明：在冰水淬冷情况下,该二元系玻璃Pbl2最大摩尔分数可达25％;玻璃转变温度介于194～201℃之间,并随着PbI2掺量增加而降低;该系统玻璃的微结构为网络形成体As2S3以[ASS3／2]三角锥结构单元存在,通过共用S或S-S连结形成无序网络状结构八面体构型的配位多面体[PbI6]为网络修饰体,通过S-I键与EAsS3／2]三角锥连接,从而均匀地分布于玻璃网络之中。由于S-I键的形成,S的正电荷升高,增加了与As之间的排斥力,使[AsS3／2]网络结构变得疏松。     

新型硫系玻璃热电极化的倍频效应

为探索优良非线性光学玻璃材料,研究了不同磷族元素掺入对GeS2-Ga2S3玻璃结构和性能的影响.利用传统的熔融淬冷技术,制备了0.8GeS2·0.1Ga2S3·0.1X2S3(X=P,As,Sb)3种硫系玻璃.差热分析表明:所制备的3种硫系玻璃的晶化温度和转变温度之差均大于100K,具有较好的成玻性能.Raman光谱、远红外光谱、可见-近红外光谱、Maker条纹等方法对3种硫系玻璃的结构和性能进行了分析.结果表明:玻璃内部存在较多的多面体单元可以导致玻璃在热电极化后出现较大的二阶非线性光学性能,玻璃在可见光波段透过率的不同将会导致在Maker条纹仪记录倍频光强度时出现反射和透射的倍频效应.     

高温高压下利用金刚石压腔实验技术对材料Raman光谱的研究

金刚石对顶砧装置(diamond anvil cell, DAC)是静态超高压装置的一种,由于金刚石具有高的硬度和良好的透光性,因此这种装置所实现的压力和能测量物性的种类都优于其他高压装置.Raman 光谱是表征物质结构及其变化的一种重要手段,DAC 超高压实验技术与激光Raman 光谱测试方法相结合, 为高压下物质结构相变研究提供了一种有效途径.实验利用金刚石压腔实验技术在高温高压条件下对氧化镓、硫酸锶固体材料进行了Raman光谱的测量.     

玄武岩熔体的析晶性能研究

实验研究了玄武岩及其添加SiO_2试样熔化后高温熔体的温度-粘度曲线及熔体水淬后玻璃态试样的析晶性能。得到了试样的温度-粘度曲线和析晶温度范围,并对它们进行了分析比较。实验结果表明,粘度、析晶性能随着温度的变化而变化,同时也显示了化学组成的变化对熔体粘度和析晶性能产生较大的影响。     

Y2O3掺杂对硅酸盐玻璃结构及其熔体黏度的影响

为了探索稀土氧化物Y2O3掺杂对硅酸盐玻璃结构及其高温熔体黏度的影响,用熔融-水淬法制得了掺杂不同含量Y2O3的Na2O-CaO-SiO2系玻璃料,采用激光共聚焦Raman光谱仪和高温旋转黏度计分别对玻璃料进行了Raman光谱和黏度的测试,根据Arrhenius方程推算了玻璃的熔制温度,同时给出了计算玻璃结构中每个四面体中的氧数、非桥氧数、平均桥数及非桥氧比例的公式.结果表明:Y2O3的掺杂使得Na2O-CaO-SiO2系玻璃中,具有不同非桥氧的结构单元之间发生了一定转化.随着Y2O3掺杂量的增加,玻璃中每个四面体中的氧数和非桥氧数都逐渐增大,玻璃中每个四面体中的连接数降低.此外Y2O3的掺杂降低了Na2O-CaO-SiO2系玻璃的高温黏度与熔制温度,且与玻璃结构的变化规律相一致.     

水泥预分解系统粉尘与碱、氯、硫融体的粘结特性及其对结皮的影响

采用化学试剂和生产原料,研究了预分解系统内粉尘与碱、氯、硫等单一或复合低温融体之间的粘结特性。结果表明：作为低温融体,KCl和混合融体KCl K2SO4 Na2SO4粘(融)结粉尘的粘结能力最强,对结皮堵塞的影响最大;其次是CaCl2,Na2SO4和混合融体CaCl2 K2SO4 Na2SO4;而单一的K2CO3和K2SO4对结皮的影响较小。作为粉尘,CaSO4最容易被各种融体粘结形成坚硬结皮;C2S与CaCO3较容易被融体粘结形成疏松结皮;CaO,Al2O3,MgO,Fe2O3,SiO2不易被融体粘结。分解率高(98％)的生料不容易被融体粘结;分解率低的生料较容易被粘结形成结皮。因此,提高入窑生料分解率不会增加而是可减少结皮堵塞的几率。     

A Limited Review of Water Diffusivity and Solubility in Glasses and Melts

A limited review of the literature dealing with water solubility and diffusion in oxide glasses and melts is presented, with an emphasis on simple and commercial compositions and on work during the past decade. Several methods for determination of water solubilities and diffusivities are discussed. Experimental results are presented for silicate, borate, and germanate glasses and melts. Water diffusivities always increase with increasing temperature and modifier oxide content in these melts. Variations in water solubility and diffusivity with alkali and alkaline earth identity for otherwise identical compositions are small, while variations with the identity of the glass-forming oxide are large. Water solubility increases with increasing modifier oxide content in alkali silicate melts, but decreases with increasing modifier oxide content in alkali borate and germanate melts.     

Impact of nanosilicates on poly(vinylidene fluoride) crystal polymorphism: Part 1. Melt-crystallization at high supercooling

Polymorphism of poly(vinylidene fluoride), PVDF, in the presence of Lucentite STN organically modified silicate (OMS) is investigated for PVDF nanocomposites melt-crystallized at high supercooling temperatures where neat PVDF crystallizes exclusively in the alpha crystalline phase. Nanocomposites were prepared from solution with 0-1.0 wt% OMS composition. Here we observed that clay addition promotes gamma phase formation in nanocomposites melt-crystallized at high supercooling (i.e., at low crystallization temperature), whereas previously we showed that even small amount of nanosilicates resulted in beta phase formation in cold-crystallized PVDF nanocomposites [1].Wide-angle X-ray scattering (WAXS), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) studies showed that α- and γ-phases co-existed in nanocomposites containing up to 0.1 wt% OMS, and the amount of α-crystals substantially diminished for higher OMS content. Formation of γ-crystal phase was confirmed with morphologic observation of spherulites of low-birefringence using polarizing optical and atomic force microscopies, and their crystalline structures were verified by FTIR and Raman microscopic spectroscopy. We also address in this work the ambiguities in assessing PVDF crystallographic phases, and correct the phase identification errors which have persisted up to this point in the literature based on melting point confusion. The crystal phase identification for PVDF nanocomposites is discussed and clarified, based on X-ray scattering, vibrational spectra, and thermal analysis. For reference, we provide a vibrational band list, indicating the close, or overlapping bands, of the three phases of PVDF: α, β and γ.     

拉曼光谱的发展及应用

本文阐述了拉曼光谱产生的基本原理;介绍了拉曼光谱的发现、发展过程;讨论了表面增强拉曼光谱技术、高温拉曼光谱技术、共振拉曼光谱技术、共焦显微拉曼光谱技术和近年来在不同领域的应用及研究新进展.     

Surface,microstructure and optical properties of copper-doped diamond-like carbon coating deposited in pulsed cathodic arc plasma

Diamond-like carbon (DLC) coating doped with copper has been deposited on silicon substrate by pulsed cathodic arc plasma using a composite cathode made of graphite with inserted copper rods. The surface morphology, microstructure and distribution patterns of elements in the coating and substrate have been studied by atomic force microscopy, scanning electron microcopy, Raman spectroscopy and energy dispersive spectroscopy. The results show that the studied coating is very well-adhered to the silicon substrate, with no microcracks, microvoids, localized delaminations or other defects being observed at the coating/substrate interface. It is also shown that the studied coating has layered microstructure and its surface is very smooth, however containing a few of nano-sized particle-like projections of copper oxide that seems to be a specific feature of all the pulsed methods used for deposition of DLC coatings doped with metals. The distribution patterns of elements in the microstructure of the studied coating are discussed. The relationship between refractive index of the coatings, and the intensity ratio of D and G peaks in the Raman spectrum has been established.     

In Situ Raman Indentation of β-Eucryptite: Characterization of the Pressure-Induced Phase Transformation

A pressure-induced phase transformation in the lithium aluminum silicate β-eucryptite was studied with in situ Raman spectroscopy. Dense β-eucryptite composites were made via powder synthesis followed by sintering. The specimens were then subjected to diamond indentation up to applied contact stresses of about 8 GPa, while collecting Raman spectra. The appearance of a Raman peak (∼520 cm⁻¹) at a contact stress of about 3 GPa likely corresponds to the reversible phase transformation of β-eucryptite to the orthorhombic phase ɛ-eucryptite. Loading and unloading in situ Raman indentation experiments are discussed with regards to this transformation.