固体核磁共振技术在锂/钠离子电池碳负极中的应用及研究进展

碳负极材料作为锂/钠离子电池的传统负极材料一直获得广泛的推广和应用，但其仍存在充电时间长、库伦效率低等问题，研究碳负极材料充放电机理是解决这些问题的关键.固体核磁共振（NMR）技术是一种研究固体材料中目标原子所处化学环境以及材料内部结构变化的有效手段.通过测定锂/钠离子电池中⁶Li、⁷Li和²³Na高速魔角旋转（MAS）条件下的固体NMR谱图，能够清晰获得锂/钠离子电池碳负极脱/嵌过程中的结构变化，以及碳原子与Li/Na的配位情况，从而为碳负极材料的设计及其电化学性能的提升提供充分的理论依据.本文综述了近年来固体NMR技术在锂/钠离子电池碳负极材料研究中的应用以及相关研究进展.     

XRD和FTIR的掺硅酸钠富水材料强度演化机制

硅酸盐水泥和铝酸盐水泥是广泛应用的无机注浆材料,混合使用这两种材料可制备凝结时间短及强度高的胶凝材料。然而,在富水条件下（水灰比大于1）,添加适量二水石膏所制备的硅酸盐-铝酸盐水泥基材料水化后期发生强度衰减。为了改善硅酸盐-铝酸盐水泥基富水材料的强度性能,将一定量的硅酸钠掺入硅酸盐水泥-铝酸盐水泥-二水石膏三元体系中。采用RMT-150力学试验系统测试含不同硅酸钠掺入量的硅酸盐-铝酸盐水泥基富水材料的强度,分析其强度演化特性及掺入硅酸钠对其强度的影响;采用扫描电镜（SEM）,X射线衍射（XRD）及傅里叶变换红外光谱（FTIR）对不同硅酸钠掺量的富水材料微观结构进行表征,分析其微观形貌、物相的变化规律,进而揭示该富水材料的强度演化机制。强度试验结果显示,不掺硅酸钠的富水材料早期强度低,并且后期强度发生衰减;而硅酸钠的掺入有助于提高硅酸盐-铝酸盐水泥基富水材料的早期强度,并且在一定程度上减少材料固化后的后期强度衰减量,当硅酸钠掺入量高于3%以上时,可以有效控制该富水材料后期强度的衰减。SEM,XRD及FTIR研究结果表明：不掺硅酸钠的硅酸盐-铝酸盐水泥基富水材料水化14 d时,检测到所属六方晶系的物相CAH₁₀ 及C₂AH₈转变为具有立方晶系结构的C₃AH₆,这种晶型转变是导致该富水材料强度衰减的原因。相比不掺硅酸钠的富水材料,当硅酸钠掺入1%时,富水材料水化3 d生成更多的水化硅酸钙（C-S-H）凝胶,这有利于提高富水材料的早期强度;水化14 d后,XRD结果显示,在d=11.75, 6.24 Å出现C₂ASH₈的衍射峰,而直至28 d才检测到C₃AH₆（d=5.16, 3.18 Å）衍射峰,并且C₃AH₆衍射强度较不掺硅酸钠的材料低,FTIR谱3 643 cm-1处出现的振动带证实了这一发现。这说明掺入1%硅酸钠促使六方晶系（CAH₁₀ 及C₂AH₈）转变为C₂ASH₈,进而抑制了CAH₁₀及C₂AH₈向C₃AH₆的转变。但是,添加1%的硅酸钠却不足以完全抑制富水材料水化后期的晶型转变,因此富水材料水化后期仍会发生强度衰减。当硅酸钠掺入量升至4%时,硅酸盐-铝酸盐水泥基富水材料中的C₂ASH₈生成量显著增大,并且水化28 d后未检测到C₃AH₆,表明富水材料内的晶型转变完全得以抑制,材料水化后期强度衰减得到有效控制。     

XRD与SEM的钢渣尾渣物理激发机理研究

钢渣是冶金工业中产生的主要固体废弃物,其产量约为每年粗钢产量的15%~20%。由于技术的局限,导致我国钢渣利用率较低,仅为年钢渣产量的10%;同时加之管理制度的不健全,导致钢渣大量露天堆放,对土地资源、地下水源,以及空气质量造成严重影响。固体废弃物再利用是资源可持续发展的重要途径之一,由于钢渣的主要化学成分(CaO,SiO₂,A1₂O₃,MgO,Fe₂O₃,MnO,f-CaO等)、主要矿物组成(硅酸三钙、硅酸二钙、钙镁橄榄石、钙镁蔷薇辉石、铁酸二钙等)与水泥熟料的主要化学成分、主要矿物组成极为相似,是一种具有潜在胶凝活性的胶凝材料。以钢渣尾渣作为研究对象,采用机械研磨的方式对钢渣尾渣处理,即物理激发,获得不同粒径钢渣尾渣微粉。依据《用于水泥和混凝土中的钢渣粉》(GB/T 20491-2006)与《水泥胶砂强度检验方法(ISO法)》(GB/T 17671-1999)制备一系列钢渣尾渣胶砂试块(分别标记为A₄₀,A₆₀,A₈₀,A₁₀₀和A₁₂₀)。研究对钢渣尾渣胶凝活性的影响,以及不同水化时间对钢渣尾渣胶凝活性的影响,即3 d钢渣尾渣胶砂强度、7 d钢渣尾渣胶砂强度与28 d钢渣尾渣胶砂强度。利用激光粒度分析仪(LPSA)对钢渣尾渣微粉的粒径分布进行测试与分析,X射线衍射仪(XRD)对钢渣尾渣微粉与钢渣尾渣胶砂的矿物组成进行测试与分析,扫描电子显微镜(SEM)进行微观形貌测试与分析,从而获得钢渣尾渣的物理激发机理。结果表明,随着钢渣尾渣微粉粒径的减小,其胶凝活性呈现先增加后降低的趋势,当研磨时间为80 min时,A₈₀钢渣尾渣微粉的胶凝活性最高,即3 d活性指数为67.55%、7 d活性指数为71.96%和28 d活性指数为73.61%。随着钢渣尾渣微粉粒径的减小,钢渣尾渣微粉中RO相的XRD特征峰强度稳定,Ca₂SiO₄与Ca₃SiO₅的XRD特征峰强度呈现先增加后降低的趋势,Ca₃SiO₅与Ca₂SiO₄参与水化反应,生成一定量的Ca(OH)₂与C-S-H凝胶,具有良好的胶凝活性。A₈₀钢渣尾渣微粉中Ca₂SiO₄含量较少,而Ca₃SiO₅含量较多,均可以生成一定量的Ca(OH)₂与C-S-H凝胶,小幅提高A₈₀钢渣尾渣胶砂的早期(3~7 d)力学性能,大幅提高A₈₀钢渣尾渣胶砂的中、后期(7 d~28 d)力学性能。当水化时间3 d时,A₈₀钢渣尾渣胶砂中存在少量水化产物且大量分散小颗粒;当水化时间7 d时,A₈₀钢渣尾渣胶砂中水化产物大幅增加且形成较大颗粒;当水化时间28 d时,A₈₀钢渣尾渣胶砂中形成大量水化产物且几乎不存在分散小颗粒。从而进一步实现固体废弃物的资源化再利用,达到钢铁企业增加效益,环境缓解压力的目的。     

低场核磁共振：弛豫和扩散的多维实验

近年来，低场核磁共振日益展示其在弛豫与扩散测量中的有效应用。在材料研究领域，诸如催化剂的研制、水泥的水化、岩石及土壤中的液体输运等，以及地质勘探和医疗诊断学中的人体组织性质的表征方面，核磁共振的弛豫与扩散测量都十分重要。特别是此技术在多维度方法方面的发展，大大促进了其在多孔材料方面的应用。多孔材料在人们生活的环境中无所不在，其微结构（微米级至毫米级）对于其性质和应用方面，具有决定性的作用。该文概述低场核磁共振的弛豫及扩散的多维度技术的基本原理、核磁共振方法学及其应用的若干关键性进展。     

水化磷脂层中蛋白质和多肽的高分辨固体核磁共振波谱学

有序样品的固体核磁共振(NMR)已快速发展成测定蛋白质和多肽在“仿真”水化磷脂层中高分辨结构的重要谱学方法. 由于与膜相连的蛋白质和多肽的结构、动力学和功能往往都和其周边自然环境密切相关,因此人们把蛋白质和多肽有序排列于水化磷脂层中进行固体NMR测量, 从而获得与取向相关的各向异性自旋相互作用. 这些取向约束可作为结构参数重构蛋白质在水化磷脂层中的高分辨三维结构. 近十年来在样品制备,NMR探头和实验方法方面的显著发展,极大地促进了有序样品的固体NMR的发展,并使之成为测定与膜相连的蛋白质和多肽结构的有效方法. 该综述介绍有序样品的固体NMR谱学方法,并总结此领域里的最新研究进展.     

基于固体核磁共振技术的固体酸结构、酸性及活性分析

固体酸是工业烃转化和生物质精炼中应用最广泛的非均相催化剂之一，了解它们的局部结构和酸性等性质有利于合理设计高效绿色固体酸催化剂，从而提高目标反应的活性和稳定性.近年来，固体核磁共振波谱在定性和定量表征固体酸的局部结构和酸性方面已显示出巨大的应用潜力，甚至可作为一种标准方法.二维固体核磁共振波谱的应用可以进一步揭示固体酸表面位点的结构对称性和不同位点的空间构效关系，从而加深对“催化剂结构-酸性-活性关系”的理解.在这篇综述中，我们总结了用于固体酸表征的固体核磁共振波谱方法和常规实验操作流程，并着重阐述了在使用和不使用探针分子的情况下，固体核磁共振波谱应用于固体酸局部结构和酸性性质研究的进展.     

固体核磁共振技术在气体水合物研究中的应用

气体水合物是在低温高压条件下由气体和水形成的笼型化合物,主要有I型,II型和H型3种晶体结构,而固体核磁共振（solid state NMR）是测定其水合指数、笼占有率等结构参数的重要手段. 该文综述了固体核磁共振技术的原理及其在水合物研究中的应用,着重介绍固体核磁共振在水合物结构表征、气体组分的鉴定、结构转化、以及在水合物生成/分解动力学过程监测方面的研究进展. 同时,对其实验方法及测试条件也进行了详细的探讨.     

固体核磁共振技术在骨基生物材料研究中的应用

骨是人体的结构组织之一,又是重要的造血器官,它在支持和保护体内器官、贮存钙和磷、参与人体代谢和为肌肉提供附着等方面具有重要的作用,因此了解骨的微观结构对预防和治疗骨疾病有重要意义.由于骨形态多样化,无机和有机成分共存,而且骨样品对物理和化学处理十分敏感,因此对其研究存在许多实验困难.与其他表征技术相比,固体核磁共振（NMR）检测对骨样品不需要任何处理,不会破坏其自身结构,可以实现原位检测.另外,骨头中的许多元素（¹H、¹³C、³¹P、¹⁹F、⁴³Ca、²⁹Si、²⁵Mg和⁸⁷Sr）都是NMR可观察核,因此高分辨固体NMR技术是研究骨基生物材料的强有力工具.该文综述了近年来固体NMR技术在骨基生物材料研究中的应用进展.     

低场核磁共振:弛豫和扩散的多维实验（英文）

近年来,低场核磁共振日益展示其在弛豫与扩散测量中的有效应用.在材料研究领域,诸如催化剂的研制、水泥的水化、岩石及土壤中的液体输运等,以及地质勘探和医疗诊断学中的人体组织性质的表征方面,核磁共振的弛豫与扩散测量都十分重要.特别是此技术在多维度方法方面的发展,大大促进了其在多孔材料方面的应用.多孔材料在人们生活的环境中无所不在,其微结构(微米级至毫米级)对于其性质和应用方面,具有决定性的作用.该文概述低场核磁共振的弛豫及扩散的多维度技术的基本原理、核磁共振方法学及其应用的若干关键性进展.     

磷酸苯基二乙基酯的合成及NMR和ESI-MS/MS测定

在冰盐浴条件下,将DEPH和CCl₄混合液滴加到由苯酚、三乙胺、二氧六环组成的混合液中或由水杨酸乙酯, 三乙胺、二氧六环组成的混合液中. 分别用二乙基亚磷酸酯（DEPH)对苯酚和水杨酸乙酯进行磷酰化. 经电喷雾质谱（ESI-MS)及核磁共振检测,目标产物存在, 其分别为磷酸苯基二乙基酯和o-(邻乙氧甲酰（基）苯基)磷酸二乙酯.     

Microstructure and texture of cementitious porous materials

We have characterized the microstructure of different cementitious materials (white and Portland cement pastes, mortars, concretes) by different magnetic resonance techniques. In particular, we show how the measurement of proton nuclear magnetic spin-lattice relaxation as a function of magnetic field strength (and hence nuclear Larmor frequency) can provide reliable information on the dynamics of proton species at the surface of CSH, the specific surface area and the pore size distribution throughout the progressive hydration of cement-based materials. The measurement does not require any drying temperature modification and is sufficiently fast to be applied continuously during the progressive hydration of the material. Coupling this method with the standard proton nuclear spin relaxation and high-resolution NMR allows us to follow the development of microscale texture within the material.     

Compositional analysis of multi-element magnetic nanoparticles with a combined NMR and TEM approach

The increasing interest in nanoscale materials goes hand in hand with the challenge to reliably characterize the chemical compositions and structural features of nanosized objects in order to relate those to their physical properties. Despite efforts, the analysis of the chemical composition of individual multi-element nanoparticles remains challenging—from the technical point of view as well as from the point of view of measurement statistics. Here, we demonstrate that zero-field solid-state nuclear magnetic resonance (NMR) complements local, single particle transmission electron microscopy (TEM) studies with information on a large assembly of chemically complex nanoparticles. The combination of both experimental techniques gives information on the local composition and structure and provides an excellent measurement statistic through the corresponding NMR ensemble measurement. This analytical approach is applicable to many kinds of magnetic materials and therefore may prove very versatile in the future research of particulate magnetic nanomaterials.     

A stray-field imaging,CRAMPS and MQMAS study of the drying process of precasting materials used in a steel-making converter

Optimization of the drying process conditions in a steel-making converter in a steel works is very difficult since the process is off-line and time-consuming. However, it is important to optimize drying process conditions (temperature, surface active agents, etc.), as steam explosion can readily occur with insufficient drying time. To help understanding, we have demonstrated that we can monitor the drying of real refractory mortar with stray-field imaging. We chose, this method because of the possibility of detecting shortT ₂ components. This paper shows the effect of varying water content in different materials on the drying rate. In particular, we find that the free-water loss rate is relatively independent of water content. However the bound-water loss rate is more affected. Also, solid-state nuclear magnetic resonance (NMR) (¹H-CRAMPS and²⁷Al M(3 and 5)QMAS) studies are performed to clarify the change of chemical structure by drying treatment. It is clear that imaging and solid-state NMR give useful information to optimize drying conditions. With this data, we can adjust and optimize the drying process and time in steel works.     

固体核磁共振技术在甲醇制烯烃反应中的应用

甲醇制烯烃过程是由非石油路线生成低碳烯烃的重要途径之一.分子筛因具备独特的孔结构和可调变的酸性质,而成为甲醇制烯烃过程的核心催化剂.固体核磁共振(NMR)是鉴定物质结构、阐释催化反应机理的强有力的工具,在甲醇制烯烃的研究中被广泛应用.本文主要总结了近年来利用原位固体NMR、多维多核NMR、脉冲梯度场NMR等固体NMR技术研究甲醇制烯烃反应机理取得的重要进展.原位固体NMR可以在真实反应条件下监测催化反应中反应物、中间体和产物的动态演变过程;多维多核NMR可以在不破坏催化剂结构情况下确定反应中间体结构信息,特别是¹²⁹Xe NMR可以很灵敏探测反应中催化剂的孔道结构变化;脉冲梯度场NMR可用于测定孔道内分子的扩散系数,阐明分子筛的扩散机制.     

Cracks and pores – Their roles in the transmission of water confined in cementitious materials

Cement paste is formed through a process called hydration by combining water with a cementitious material. Concrete, the worlds most versatile and most widely used material, can then be obtained when aggregates (sand, gravel, crushed stone) are added to the paste. The quality of hardened concrete is greatly influenced by the water confined in the cementitious materials and how it is transmitted through cracks and pores. Here we demonstrate that the water transport in cracks and capillary pores of hardened cement pastes can be approximately modeled by simple equations. Our findings highlight the significance of arresting the development of cracks in cementitious materials used in repository barriers. We also show that neutron scattering is an advantageous technique for understanding how water transmission is effected by gel pore structures. Defining measurable differences in gel pores may hold a key to prediction of the reduction of water transport through cement barriers.     

High-Resolution Solid-State NMR Spectroscopy of Steroids and Their Derivatives

Abstract: Steroids are an important class of organic compounds containing a vast array of biologically and physiologically essential molecules. Due to their availability, relatively straightforward derivatizability, and endogeneity, they are widely used in pharmacological applications. The investigation of molecular and physicochemical properties of active pharmaceutical ingredients (APIs) in the solid state is important, because these properties are directly related to their pharmacological activity. Several methods are available for this purpose. Solid-state NMR spectroscopy offers a nondestructive and flexible technique, providing both structural and dynamic information. It can be applied to every solid physical state (both crystalline and amorphous) as well as to materials with different compositions. The current article aims at gathering together some of the recent and most important studies in the area of high-resolution solid-state NMR spectroscopy of steroids and their derivatives completed with related theoretical reports not forgetting to outline the future remarks.     

Structure solution of network materials by solid-state NMR without knowledge of the crystallographic space group

An algorithm is presented for solving the structures of silicate network materials such as zeolites or layered silicates from solid-state ²⁹Si double-quantum NMR data for situations in which the crystallographic space group is not known. The algorithm is explained and illustrated in detail using a hypothetical two-dimensional network structure as a working example. The algorithm involves an atom-by-atom structure building process in which candidate partial structures are evaluated according to their agreement with SiOSi connectivity information, symmetry restraints, and fits to ²⁹Si double quantum NMR curves followed by minimization of a cost function that incorporates connectivity, symmetry, and quality of fit to the double quantum curves. The two-dimensional network material is successfully reconstructed from hypothetical NMR data that can be reasonably expected to be obtained for real samples. This advance in “NMR crystallography” is expected to be important for structure determination of partially ordered silicate materials for which diffraction provides very limited structural information.     

Spatially resolved solid-state MAS-NMR-spectroscopy

A comprehensive account of spatially resolved solid-state MAS NMR of ¹³C is given. A device generating field gradients rotating synchronously with the magic angle spinner is described. Spatial resolution and sensitivity are compared for phase and frequency encoding of spatial information. The suppression of spinning sidebands is demonstrated for both cases. Prior knowledge about the involved materials can be used for the reduction of data from spatially resolved spectra to map chemical structure. Indirect detection via ¹³C NMR gives access to the information about mobility from proton-wideline spectra. Two-dimensional solid-state spectroscopy with spatial resolution is demonstrated for a rotor-synchronized MAS experiment which resolves molecular order as a function of space. By comparison of different experiments the factors affecting the spatial resolution are investigated.     

NMR方法在煤炭分析中的应用进展

简要介绍了核磁共振（NMR）方法在煤炭组成及热解过程分析中的应用. 目前用于煤炭分析的NMR方法主要包括固体NMR和液体NMR. 从检测手段来看,以¹³C NMR和¹H NMR方法较多,¹⁵N NMR, ¹⁹F NMR和³¹P NMR也在煤炭的分析中发挥了重要作用. 其中用于区分和选择性检测不同官能团的NMR谱编辑方法的发展, 进一步推进了NMR在煤炭化工中的应用.