Preparation and Structural Investigation of CuCl2 Graphite Intercalation Compounds

Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a mixture of anhydrous CuCl2 and graphite nanosheets. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy were performed to characterize the microstructures of stage-1 nano-scale CuCl2 graphite intercalation compounds. The structure and components of the domain wall and core in the nano-scale CuCl2 graphite intercalation compounds are described. The results show that the content of CuCl2 in the mixture plays a crucial role in the size of the nano-scale CuCl2 graphite intercalation compound.     

A review on the synthesis and applications of green rust for environmental pollutant remediation

This paper discusses the various approaches to the synthesis of green rust. Green rusts are synthesized by changing the average oxidation state of iron compounds so that the ratio of ferric/ferrous ions is between 0.25 and 0.33. This can be achieved by mixing ferrous and ferric hydroxides, oxidation of ferrous compounds or reduction of ferric compounds. Characterization of the samples with analytical methods such as Mossbauer spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy, transmission electron microscopy and atomic-force microscopy is discussed. Green rusts have a layered double hydroxide structure, with an interchangeable anion layer and a mixed ferrous–ferric cation layer. This structure can adsorb ions by intercalation or exchange anions with its environment. The cation layer can oxidize, which gives a reducing nature to green rusts. These properties make them excellent candidates for the reduction and immobilization of several inorganic pollutants. Green rusts also have applications in dechlorination of organic compounds and in the synthesis of nanohybrid materials. These environmental and nanochemistry applications are also covered in this paper.     

钾膨胀石墨层间化合物(K-EGIC_S)的电阻率测量

在低温惰性条件下合成的钾膨胀石墨层间化合物 (K_EGICS)的电学性能与膨胀石墨的电学性能完全相反 ,随着温度的升高 ,K_EGICS 的电阻率逐渐升高 ,电导率逐渐降低。这一现象是由客体材料钾自身的结构及其与膨胀石墨化合时的键性决定的。     

An exotic kind of cosmic material: graphite-containing xenoliths from the Krymka (LL3.1) chondrite

Seven graphite-containing xenoliths were found in the Krymka (LL3.1) chondrite. The xenoliths have the following chemical and mineralogical characteristics which distinguish them from the Krymka host: (1) low totals in bulk chemical analyses obtained by electron microprobe; (2) high bulk Fe abundances; (3) a uniform recrystallized, chondrule-free texture; (4) the presence of euhedral graphite and carbon-rich material; (5) higher quantities of troilite and metal; (6) a relatively homogeneous composition of silicates; (7) a distinctive composition of metal, chromite and phosphate; (8) isotopically heavy C in graphite compared to both bulk Krymka and graphite in other ordinary chondrites. The xenoliths are mineralogically similar, but not identical, to the Krymka carbonaceous clast K1, which bears graphite microcrystals, organic compounds and mysterite. They resemble carbonaceous chondrites, both chemically and isotopically. The mineralogical, chemical and isotopic data for the graphite-containing fragments suggest that this material represents metamorphosed varieties of a previously unknown type of unequilibrated carbonaceous matter. Most likely, the graphite has a metamorphic origin and was crystallized from C-containing precursor materials through the following transformation sequence: organic compounds → C-rich material → graphite.     

Microinclusions in dark gray diamond crystals of octahedral habit from Yakutian kimberlites

Micrometer-sized inclusions in dark gray diamond crystals of octahedral habit from Yakutian kimberlites were studied by analytical scanning electron microscopy and analytical transmission electron microscopy. In addition to peridotite-suite silicate inclusions (enstatie and olivine), which were previously studied in detail as macroinclusions in perfect diamond crystals, there are abundant inclusions of native metals (Fe-Cr and Fe-Cr-Ti intermetallic compounds and metallic Fe), sulfides (Fe-Ni sulfide, polydymite, and chalcopyrite), and carbonates (calcite). Rare grains of ilmenite, fluorite, apatite, zircon, phlogopite, and some other minerals were also found. The gray and black colors of diamonds were previously attributed to the presence of graphite. Although this phase was identified in the electron diffraction patterns of all the samples, its content was very low. Microinclusions of induced octahedral morphology composed of intimate enstatite-calcite intergrowths were also found. Possible deep processes responsible for the formation of diamonds with such a peculiar inclusion association are discussed in light of new data on experimental synthesis. Original Russian Text ? S.V. Titkov, A.I. Gorshkov, N.G. Zudin, I.D. Ryabchikov, L.O. Magazina, A.V. Sivtsov, 2006, published in Geokhimiya, 2006, No. 11, pp. 1209–1217.     

超无烟煤中石墨微晶产出状态与成因

超无烟煤（也称变质无烟煤）中广泛发育石墨微晶,为深入分析煤中石墨微晶产出特征及成因,以福建省永安煤田典型样品为例,采用光学显微镜、扫描电镜和透射电镜等测试方法,识别并分析煤中石墨微晶的光学性质、物质组成、晶体结构等特征,并探讨其成因。结果显示:石墨微晶主要产出于煤中微裂缝和空腔内,多数具有类似于石油焦的纤维状显微结构,可见气泡膜状结构;石墨微晶最大反射率为9.29%~10.83%,远远高于煤中原有显微组分;正交偏光加石膏试板观测条件下,石墨微晶呈现一级黄、二级蓝干涉色以及镶嵌状、区域状、纤维状等显微结构,局部定向性明显。扫描电镜加电子探针探测显示,石墨微晶多呈鳞片状并见流动状结构和气孔构造,同时显示出纯碳特点。高分辨率透射电镜观测到石墨微晶晶格条纹呈平直定向排列,选区电子衍射呈现典型的石墨晶格环斑模式。初步分析认为,煤中石墨微晶的碳质来源于高度熔融的（变）壳质组和富氢（变）镜质体,热源为侵入煤田周边及盆地底部的燕山期花岗岩,熔融含碳物质在孔缝空间内汇聚流动并在高温下脱除杂质元素,然后在强大岩浆侵位压力下结晶形成秩理性显著的石墨微晶;同时,也不排除渗出沥青质体再次活化形成研究区煤中石墨微晶的可能性。移动阅读      

New Data on Diamond–Graphite Relationships in the Gneisses of the Kokchetav Massif (Northern Kazakhstan)

The results of studying an aggregate of graphite-and-diamond crystal in tourmaline 5 μm of the Kokchetav massif by the method of transmission electron microscopy are presented. The detail studies of the interface between the crystals of graphite and diamond have revealed the absence of disordered graphite that is detail partially graphitized diamond. Intense deformation changes in the graphite crystal occurred after it was captured by tourmaline at the regression stage, which led to considerable kinking of the graphite crystal along the a-axis. Thus, the coexistence of graphite and diamond crystals cannot be unambiguously interpreted as a product of partial diamond graphitization. Graphite could have crystallized syngenetic with a diamond crystal or at the retrograde stage in the graphite stability field.

     

Influence of chlorine substitution on adsorption of gaseous chlorinated phenolics on multi-walled carbon nanotubes embedded in SiO<Subscript>2</Subscript>

Multi-walled carbon nanotubes (MWCNTs) embedded in SiO₂ particles were prepared through the floating-catalyst chemical vapor deposition method. The parameters reaction time and flow rate of the carbon source (CH₄) were studied to obtain optimum conditions for MWCNT synthesis. The obtained MWCNTs were characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy to confirm their morphology and crystallinity. The optimum conditions were a CH₄ flow rate of 100 ml/min in a H₂–Ar mixture at a flow rate of 500 ml/min and a reaction time of 20 min. Under these conditions, MWCNTs with average outer and inner diameters of around 50 and 10 nm, respectively, were obtained. SiO₂ particles with embedded MWCNTs were studied for their adsorption of gaseous chlorinated phenolic compounds (CPCs), with emphasis on the effect of number of chlorine substituents. The CPC compounds of 2-chlorophenol (CP) and 2,4-dichlorophenol (DCP) were compared against phenol (P). Adsorption of P and CPCs on the particles fit well the Langmuir isotherm. The adsorption capacities of P, CP, and DCP on SiO₂ particles with embedded MWCNTs were found to be 3.12, 13.83, and 44.25 mg/g, respectively. Desorption activation energy was determined by thermogravimetric analysis. Chlorine substitution on P changed the adsorption process from physical to chemical adsorption. The particles showed high potential for use as a pre-concentration unit for solid-phase microextraction.     

Conversion of carbonaceous material to graphite within the Greywacke Zone of the Eastern Alps

Morphology and reflectance of carbonaceous material (CM) in Late Carboniferous metasediments of the eastern Greywacke Zone (Eastern Alps) indicate a mixture of vitrinite, grainy textured and lamellar shaped particles. As imaged by high-resolution atomic-force microscopy, vitrinite and the grainy textured particles show mesophase structures which can be described as facetted nanocrystals within the carbon matrix. High-resolution transmission electron microscopy has revealed two types of microtextures representing different degrees of graphitization. The first type is characterized by elongated ring-shaped microtextures, whereas the second type is characterized by graphite lamellae and polygonal flakes with long-range ordered aromatic layers. In spite of the heterogeneity of the CMs, the geographical distribution of quantitative metamorphic parameter (Raman spectra parameter, X-ray diffraction pattern, microscopic reflectance) suggests a graphitization process which is promoted by advective heat transport during post-collisional processes. In a tentative pressure-time path, Late Cretaceous thrusting results in a turbostratic ordering of the aromatic layer. Ordering to long-range ordered aromatic layers was achieved during the Late Cretaceous-Paleogene exhumation of mid-crustal rocks beneath the eastern Greywacke Zone.     

大别山双河硬玉石英岩石英中的纳米-亚微米级流体包裹体

用透射电子显微镜(TEM)观察产于大剐山双河地区含柯石英硬玉石英岩矿物石英中纳米级至亚微米级的流体包裹体超微观结构特征发现：大多数包裹体呈圆形或负晶形(粒径大多为10nm～350nm),构成宽的密集的包裹体串。TEM揭示了柯石英和寄主矿物石英之间为共晶格取向连生关系,并寻找到在峰期变质条件下高盐流体存在的有力证据。流体包裹体经常伴随着许多相互连接的位错,并且与位错和位错壁等交生在一起,形成网络分布,这是在光学显微镜尺度下所不能探测到的。非爆裂的流体渗漏可能通过H2O或CO2分子沿位错的管道扩散,从包裹体进入寄主矿物石英,因而导致原来包裹体密度和成分的变化。     

Effect of the activation temperature over activated carbon production from castor cake and its evaluation as dye adsorbent

In this work, castor cake produced as a by-product in castor oil extraction was used for activated carbon production. Castor cake was chemically treated with a K₂CO₃ solution, and the effect of the pyrolysis temperature in the 500–900 °C range was studied. Materials were characterized by X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy and nitrogen adsorption–desorption at ?196 °C. Methylene blue adsorption was selected as a test probe to stress the removal capacity of the prepared materials. By the X-ray powder diffraction analysis, carbon obtaining in its graphite allotropic form together with other inorganic compounds was verified. Scanning electron microscopy images evidenced the generation of porosity in the thermally treated samples compared with the pristine compound. In addition, the specific surface area values augmented progressively with the thermal treatment increment achieving a value of 1015 m² g^?1 in the 900 °C calcined sample. Calcination at 800 °C and m/V = 0.003 ratio were the best parameter combination to achieve a 99.6% methylene blue uptake.     

The influence of pressure and composition on the viscosity of andesitic melts

The effect of pressure and composition on the viscosity of both anhydrous and hydrous andesitic melts was studied in the viscosity range of 10⁸ to 10^11.5 Pa · s using parallel plate viscometry. The pressure dependence of the viscosity of three synthetic, iron-free liquids (andesite analogs) containing 0.0, 1.06, and 1.96 wt.% H₂O, respectively, was measured from 100 to 300 MPa using a high-P-T viscometer. These results, combined with those from Richet et al. (1996), indicate that viscosities of anhydrous andesitic melts are independent of pressure, whereas viscosities of hydrous melts slightly increase with increasing pressure. This trend is consistent with an increased degree of depolymerization in the hydrous melts. Compositional effects on the viscosity were studied by comparing iron-free and iron-bearing compositions with similar degrees of depolymerization. During experiments at atmospheric and at elevated pressures (100 to 300 MPa), the viscosity of iron-bearing anhydrous melts preequilibrated in air continuously increased, and the samples became paramagnetic. Analysis of these samples by transmission electron microscopy showed a homogeneous distribution of crystals (probably magnetite) with sizes in the range of 10 to 50 nm. No significant difference in the volume fractions of crystals was found in samples after annealing for 170 to 830 min at temperatures ranging from 970 to 1122 K. An iron-bearing andesite containing 1.88 wt.% H₂O, which was synthesized at intrinsic fO₂ conditions in an internally heated pressure vessel, showed a similar viscosity behavior as the anhydrous melts. The continuous increase in viscosity at a constant temperature is attributed to changes of the melt structure due to exsolution of iron-rich phases. By extrapolating the time evolution of viscosity down to the time at which the run temperature was reached, for both the anhydrous (at 1055 K) and the hydrous (at 860 K) iron-bearing andesite, the viscosity is 0.7 log units lower than predicted by the model of Richet et al. (1996). This may be explained by differences in structural properties of Fe²⁺ and Fe³⁺ and their substitutes Mg²⁺, Ca²⁺, and Al³⁺, which were used in the analogue composition.The effect of iron redox state on the viscosity of anhydrous, synthetic andesite melts was studied at ambient pressure using a dilatometer. Reduced iron-bearing samples were produced by annealing melts in graphite crucibles in an Ar/CO atmosphere for different run times. In contrast to the oxidized sample, no variation of viscosity with time and no exsolution of iron oxide phases was observed for the most reduced glasses. This indicates that trivalent iron promotes the exsolution of iron oxide in supercooled melts. With decreasing Fe³⁺/ΣFe ratio from 0.58 to 0.34, the viscosity decreases by ∼1.6 log units in the investigated temperature range between 964 and 1098 K. A more reduced glass with Fe³⁺/ΣFe = 0.21 showed no additional decrease in viscosity. Our conclusion from these results is that the viscosity of natural melts may be largely overestimated when using data obtained from samples synthesized in air.     

Modulated structures in calcian dolomite: A study by electron microscopy

Calcian dolomite from the Devonian Lost Burro formation has been investigated with electron microscopy techniques. Electron diffraction shows evidence for “c” and “d” type reflections which may occur independently and are indicative of ordered superstructures. High resolution electron microscopy combined with selected area optical diffraction is the basis for models to explain the superstructures in calcian dolomite. It is proposed that “c” reflections are due to ordered substitution of Mg by Ca in basal cation layers. “d” reflections result when the rhombohedral stacking of basal layers is interrupted by intercalation of additional Ca layers. During electron irradiation at 1 MeV the Mg-Ca distribution becomes disordered and the crystal structure attains calcite symmetry. The arrangement of CO₃ groups remains ordered.     

不同变质程度煤系石墨结构特征

煤系石墨形成于煤层的接触变质带,通常被当作煤开采利用而造成严重的资源浪费.为了了解煤系石墨在成矿过程中分子结构的变化,利用X射线衍射（XRD）、透射电子显微镜（TEM）、拉曼光谱（Raman）等技术,对我国陕西凤县、湖南新化和湖南郴州鲁塘地区处于不同变质程度煤系石墨进行测试分析.结果表明:凤县样品石墨化度最低,仍处于超无烟煤阶段;新化石墨处于半石墨阶段,鲁塘样品石墨化程度最高,其结构比较完美,接近于三维有序理想石墨结构,但仍存在少量的无序化畴.XRD分析显示随着样品石墨化程度的升高,堆砌层数与堆砌延展度均增大;拉曼光谱中D峰减弱,G峰逐渐增强并尖锐,D峰与G峰的强度比和面积比均减小,显示碳原子sp2平面域增大.透射电子显微镜晶格像显示,由无烟煤向石墨结构转变过程中,煤的芳香片层首先形成类石墨结构的微柱体,然后这些微柱体之间相互联结,最后形成横向无限延展的石墨晶层.      

高岭石/乙酰胺插层复合物的制备及结构表征

乙酰胺在熔融状态下直接插层高岭石，产物经无水乙醇洗涤，得到纯净的高岭石／乙酰胺插层复合物。XRD结果显示高岭石层间距从0．721nm膨胀到1．102nm。插层作用使得高岭石内表面羟基伸缩振动峰由3651cm^-1。移动至3647cm^-1。处，变形振动峰由911cm^-1移动至907cm^-1处；乙酰胺3211cm^-1和3390cm^-1处NH2基伸缩振动峰消失，并在3478cm^-1处产生一新的振动峰，这些表明原高岭石层问氢键的损失及与乙酰胺分子之间氢键的形成。高岭石内羟基的吸收峰由3616cm^-1移动至3611cm^-1处，以及其硅氧面的骨架振动峰变化表明乙酰胺的甲基中CH嵌入到高岭石的复三方空穴中。进而构建高岭石／乙酰胺插层复合物的结构模型，结果表明该模型的理论计算值与实际测量结果具有很好的一致性。     

碳材料在环境工学方面的应用

主要介绍了碳材料在石油废水处理，给排水水质处理、大气治理中的应用。膨胀石墨含有大量孔隙，密度很低，用作吸附材料可以治理石油废水。碳材料可作为生物增殖的载体，分解生物能降解的污染物。用于给排水水质处理，能够提高水质；而经过特殊处理的石墨可以与金属纳米复合，形成金属基石墨层间化合物，改善石墨的抗菌性能。碳材料的比表面积大，可用作气相污染物的吸附脱除材料，在大气污染方面，表现出良好的应用前景。     

河南祁雨沟金矿床冰长石中自然铜超显微包体的发现及成因

经透射电镜研究,在祁雨沟金矿床的冰长石中发现有自然铜超显微包体。作者认为这种超显微包体是在低fs_2、fo-2、富Cl的条件下形成,Cu是以CuCl-2~-络合物形式搬运。晶出的自然铜被正在结晶的冰长石捕获,使其封闭起来,未受到后来富fs_2流体的作用。     

Poorly crystalline carbonaceous matter in high grade metasediments: implications for graphitisation and metamorphic fluid compositions

Poorly crystalline carbonaceous matter was observed in chlorite to sillimanite grade metasediments from the Trois Seigneurs Massif, in contrast to other studies of carbon crystallinity which observed well crystallised graphite under upper greenschist facies conditions. Using transmission electron microscopy four types of carbon particle were identified; globular carbon, composite flakes, homogeneous flakes and crystalline graphite. Globular carbon and composite flakes are poorly crystalline microporous carbon. Homogeneous flakes decompose in the electron beam and are probably composed of heavy volatile hydrocarbons. Graphite is confined to samples from retrograde shear zones and often occurs with globular carbon. The lack of graphitisation in metasediments is probably a consequence of the microporous structure of the carbonaceous matter combined with low f _{O 2}. The preservation of carbonaceous matter in the Trois Seigneurs metasediments is not compatible with the metasediments having been externally buffered by a high X _H2_O fluid syn-metamorphism. An alternative hypothesis of internal buffering is preferred to explain the carbonaceous matter in the Trois Seigneurs metasediments.     

Phase state of the carbonaceous matter in the metalliferous shales of the Russian Far East

Carbonaceous matter (CM) in shales of some deposits and occurrences of the Russian Far East has been studied by scanning and transmission electron microscopy, Raman spectroscopy, and X-ray phase and differential thermal analyses. It was shown that the carbonaceous matter in the high-temperature shales (amphibolite facies) of the Soyuznoe deposit is represented by holocrystalline graphite, while the low-temperature (greenschist facies) shales of the Sutyr and Kimkan sequences contain mainly nanocrystalline graphite. It was substantiated for natural objects that platinum is assimilated by graphite at high temperatures. This should be taken into account in planning the prospecting works, as well as in developing a technique for enrichment of carbonaceous ore, because high-temperature carbonaceous shales with holocrystalline graphite are promising for Pt, unlike their low-temperature analogues with nanocrystalline graphite.     

Conversion of carbonaceous material to graphite during metamorphism

Using high-resolution transmission electron microscopy (HRTEM), we have charted some of the structural changes that occur as non-crystalline organic matter in low-grade metamorphic rocks becomes ordered, eventually to form well-crystallized graphite. It has long been known from X-ray studies that the state of crystallization of carbonaceous matter increases with metamorphic grade. Images obtained by HRTEM of samples from a range of metamorphic terranes provide considerable additional detail regarding the process of graphite development. The process is considerably more complex than is suggested by light-optical microscopy and powder X-ray diffraction measurements.In low-grade metamorphic rocks, the carbon layers are relatively few in number, short in length, and rather contorted. Electron-diffraction patterns show only one or two rings, and they are diffuse. As metamorphic grade increases, the carbon layers progressively increase in length and in number, the number of layers in the crystallite stacks increases, the planarity of the layers increases, and the number of layer terminations decreases. Electron-diffraction patterns show complementary increasing numbers of rings, decreasing diffuseness, and, for well-crystallized graphite, discrete spots. Well-crystallized graphite crystals appear in the chlorite zone but, in contrast to most X-ray measurements, a range of structural order is commonly observed among the various crystallites within a given rock sample. These presumably reflect the chemical and structural character of the carbonaceous precursors, possibly their sedimentary sources, as well as the degree of internal equilibration. The results of our electron microscope observations also have implications for interpreting measurements of carbon-isotope fractionations and the apparent lack of equilibrium reported in many such measurements.