X-ray and scanning electron microscopy archaeometric studies of pigments from the Aguada culture, Argentina

X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive system (EDX) were used in order to obtain mineralogical and chemical composition of white and reddish pigments belonging to the Ambato style of “Aguada” culture, found in the archaeological site of Piedras Blancas (Catamarca, Argentina 500–1100 AD). These pigments are associated with different sectors, two of them being related to funerary context. Due the scarce amount of samples available, it was necessary to develop a new methodology for their study. X-ray diffraction spectra were collected using a low background Si sample holder, which allows the study of small sample amounts (a few milligrams). The mineral quantifications were carried out by applying the Rietveld method to the XRD spectra. The major difficulties arose for reddish pigments, since they contain iron-bearing phases, such as ferruginous clays, in which neither the concentration of Fe^{+ 2} relative to Fe^{+ 3} nor the location in the lattice (occupancy factor) is completely known. With the aim of performing quantitative elemental analysis from SEM-EDX spectra, a special sample holder for the small amounts of available samples was developed. Commercial standards were used in the quantification process and the characteristic intensities were corrected for matrix effects. Micrographs and EDX point spectra allowed the characterization of minor phases and particle analysis. The Rietveld method combined with the new procedure for EDX analysis has proven to be a suitable method for routine quantitative analysis of small amounts of archaeological pigments.     

Synthesis and characterization of core-shell selenium/carbon colloids and hollow carbon capsules

A novel Se/C nanocomposite with core-shell structures has been prepared through a facile one-pot microwave-induced hydrothermal process. The new material consists of a trigonal-Se (t-Se) core and an amorphous-C (a-C) shell. The Se/C composite can be converted to hollow carbon capsules by thermal treatment. These products were characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction (SAED), energy-dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS).     

Sol–gel combustion synthesis and characterization of nanostructure copper chromite spinel

Nanocomposite copper chromite spinel was fabricated by sol–gel process using copper nitrate trihydrate, chromium nitrate nonahydrate, ethylene glycol, diethyl ether, and citric acid. The thermoanalytical measurements (TG–DTG), X-ray powder diffractometry (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis were used to characterize the structural and the chemical features of the nanocomposites. TG–DTG results showed that the major mass loss for copper(II) nitrate, chromium(III) nitrate as precursors occur at 258 and 140 °C, respectively. The major mass loss for dried gel of copper chromite occurs at 310 °C. XRD data revealed the formation of pure copper chromite after thermal decomposition at 1,000 °C for 2 h. The observation of XRD patterns reveals the presence of single-phase tetragonal spinel CuCr₂O₄. FESEM analysis of calcined composite was found to be in the range of 20–30 nm.     

X-ray and scanning electron microscopy archaeometric studies of pigments from the Aguada culture,Argentina

X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive system (EDX) were used in order to obtain mineralogical and chemical composition of white and reddish pigments belonging to the Ambato style of “Aguada” culture, found in the archaeological site of Piedras Blancas (Catamarca, Argentina 500–1100 AD). These pigments are associated with different sectors, two of them being related to funerary context. Due the scarce amount of samples available, it was necessary to develop a new methodology for their study. X-ray diffraction spectra were collected using a low background Si sample holder, which allows the study of small sample amounts (a few milligrams). The mineral quantifications were carried out by applying the Rietveld method to the XRD spectra. The major difficulties arose for reddish pigments, since they contain iron-bearing phases, such as ferruginous clays, in which neither the concentration of Fe^+ 2 relative to Fe^+ 3 nor the location in the lattice (occupancy factor) is completely known. With the aim of performing quantitative elemental analysis from SEM-EDX spectra, a special sample holder for the small amounts of available samples was developed. Commercial standards were used in the quantification process and the characteristic intensities were corrected for matrix effects. Micrographs and EDX point spectra allowed the characterization of minor phases and particle analysis. The Rietveld method combined with the new procedure for EDX analysis has proven to be a suitable method for routine quantitative analysis of small amounts of archaeological pigments.     

静电纺丝法制备铁酸锌中空纤维及其磁学性能

以锌盐、铁盐和聚乙烯吡咯烷酮(PVP)为原料,通过静电纺丝法先制备PVP/硝酸盐复合纤维,这些复合纤维以5℃·min-1的升温速率加热到500℃并保温3h,最终得到铁酸锌(ZnFe2O4)中空纤维.通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)以及振动样品磁强计(VSM)等分析手段对中空纤维的晶体结构、形貌和磁学性能进行了研究.结果显示,ZnFe2O4中空纤维属于尖晶石结构,高温处理后仍能保持一维结构,纤维直径在200-400nm之间,纤维壁由大小为25nm的颗粒堆积而成.室温磁化结果显示制备的ZnFe2O4中空纤维具有超顺磁性,在10kOe的磁化强度为2.03emu·g-1.     

Characterization of electron-beam-modified surface coated clay fillers and their influence on physical properties of rubbers

A novel process of surface modification of clay filler has been developed by coating this with an acrylate monomer, trimethylol propane triacrylate (TMPTA) or a silane coupling agent, triethoxy vinyl silane (TEVS) followed by electron beam irradiation. Characterization of these surface modified fillers has been carried out by Fourier-transform infrared analysis (FTIR), electron spectroscopy for chemical analysis (ESCA), wettability by dynamic wicking method measuring the rise of a liquid through a filler-packed capillary tube and water flotation test, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Presence of the acrylate and the silane coupling agent on the modified fillers has been confirmed from FTIR, ESCA, and EDX studies, which has also been supported by TGA studies. The contact angle measurement by dynamic wicking method suggests improvement in hydrophobicity of the treated fillers, which is supported by water flotation test especially in the case of silanized clay. However, XRD studies demonstrate that the entire modification process does not affect the bulk properties of the fillers. Finally, both unmodified and modified clay fillers have been incorporated in styrene butadiene rubber (SBR) and nitrile rubber (NBR). Rheometric and mechanical properties reveal that there is a definite improvement using these modified fillers specially in the case of silanized clay compared to the control sample, probably due to successful enhancement in interaction between the treated clay and the base polymer.     

以煤矸石为原料合成Y型沸石及其吸附性能的探究

以固体废物煤矸石为原料,采用“高温焙烧活化 碱熔融 碱溶 陈化 晶化”水热反应体系,根据Y型沸石相应的结构特征,通过对各阶段反应条件的探究及对SiO₂/Al₂O₃的摩尔比的控制,合成Y型沸石,其结构、形貌和性能经X-射线荧光光谱、X-射线衍射、扫描电子显微镜、Fourier红外光谱和氮吸附仪分析表征。并将Y型沸石应用于氨氮废水的处理,对其吸附性能进行研究。结果表明,在活化温度800 ℃,碱熔融温度850 ℃,碱熔融质量比（Na₂CO₃/煤矸石）为1.0,碱溶NaOH溶液浓度为3 mol·L^-1,于60 ℃陈化12 h,晶化温度105 ℃,晶化时间6 h条件下,硅铝比为6~8,制得的Y型沸石结晶度最高（93％）,对氨氮废水的去除率在40 min内达到88.2%。     

Structural,morphological and magnetic properties of nano-crystalline zinc substituted cobalt ferrite system

Nano-crystalline zinc-substituted cobalt ferrite powders, Co_1−xZn_xFe₂O₄ (x = 0, 0.25, 0.5, 0.75 and 1), have been synthesized by the combustion route. The structural, morphological and magnetic properties of the products were determined and characterized in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). X-ray analysis showed that the samples were cubic spinel. The increase in zinc concentration resulted in an increase in the lattice constant, unit cell volume, X-ray density, ionic radii, the distance between the magnetic ions and bond lengths on tetrahedral sites and octahedral sites of cubic spinel structure. Opposite behavior was observed for the average crystallite size of the as synthesized solids. The variation of saturation magnetization (M_s) value of the samples was studied. The maximum saturation magnetization value of the Co_o.25Zn_0.75Fe₂O₄ sample reached 76.87 emu/g. The high saturation magnetization of these samples suggests that this method is suitable for preparing high-quality nano-crystalline magnetic ferrites for practical applications.     

Analysis and Protection of One Thousand Hand Buddha in Dazu Stone Sculptures

The components of the rock, the pigments, the gold foils and the adhesive of One Thousand Hand Buddha in Dazu stone sculptures, Chongqing, China, have been analyzed by X-ray diffraction (XRD), X-ray fluorescence (XRF), infrared spectroscopy (IR), energy dispersive X-ray analysis (EDX) and fiber optics reflectance spectroscopy (FORS). Furthermore, the weathering and degeneration of One Thousand Hand Buddha have been discussed and the protective methods have been provided. In this work some useful information to study on conservation of stone relics is given.     

A chemical, morphological, and electrochemical (XPS, SEM/EDX, CV, and EIS) analysis of electrochemically modified electrode surfaces of natural chalcopyrite (CuFeS2) and pyrite (FeS2) in alkaline solutions

Electrodic surfaces of natural chalcopyrite and natural pyrite minerals (El Teniente mine, Chile) have been studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy including microanalysis (SEM/EDX). For comparison, fractured and polished mineral surfaces were also studied by XPS. In both electrodes, the formation of Fe(III) species containing oxygen were detected and Cu(II) species containing oxygen were additionally detected for chalcopyrite at advanced oxidation states. The presence of Cu(II) species containing oxygen was not detected by XPS for the initial oxidation states of the chalcopyrite. For pyrite, the present results do not allow confirmation of the presence of polysulfurs such as have been previously proposed. In both minerals, the measurements of SEM and EDX show relevant alterations in the respective surfaces when different potential values were applied. The chalcopyrite surface shows the formation of protrusions with a high concentration of oxygen. The pyrite surface shows a layer of modified material with high oxygen content. The modifications detected by XPS, SEM, and EDX allowed the explanation of the complexity of the equivalent circuit used to simulate the experimental EIS data. At high oxidation states, both minerals showed a pseudoinductive loop in the equivalent circuit, which was due to the active electrodissolution of the minerals which takes place through a surface film previously formed.     

Role of calcination on geopolymerization of lateritic clay by alkali treatment

In the present study, the role of calcination of a low iron lateritic clay sample was investigated to synthesize the geopolymer. The analyses like X-ray fluorescence (XRF) spectroscopy for chemical composition, X-ray diffractometry (XRD) for mineral composition, and Fourier transform infrared (FT-IR) spectroscopy & scanning electron microscopy (SEM) for structural changes upon calcination at 500, 700 and, 900 °C were used to assess the suitability of selected lateritic clay sample for geopolymer. The drop in electrical conductivity and greater consumption of calcium hydroxide by CS-900 confirmed its potential reactivity than CS-700, CS-500, and CS-Control. The quality of geopolymer derived from un-calcined and calcined lateritic clay samples by alkali activation was evaluated by comparing results of compressive strength, water absorption test, and stability in the aggressive environment of chloride, FT-IR, XRD, and SEM analyses. The experimental results reveal that the quality of geopolymer enhances as the calcination temperature of the lateritic clay sample increases, However, calcination of the lateritic clay sample at 900 °C gives significant results and yield good quality geopolymer with 24.8 MPa of compressive strength, 7.07% of water absorption and 2.22% loss in mass in an aggressive environment.     

SnO2/TiO2复合纳米纤维的制备及光催化性能

采用静电纺丝技术,以聚乙烯吡咯烷酮和钛酸正丁酯为前驱体,制得锐钛矿相TiO2纳米纤维。以TiO2纳米纤维为模板,通过水热合成法,制备了具有异质结构的SnO2/TiO2复合纳米纤维。利用扫描电镜(SEM)、X射线能量色散光谱（EDS）、透射电镜(TEM)和X射线衍射(XRD)等分析测试手段对其形貌和结构进行了表征,结果表明,SnO2纳米粒子均匀地生长在TiO2纳米纤维表面,形成了异质结构的SnO2/TiO2复合纳米纤维材料。通过改变反应物浓度,能有效地实现SnO2/TiO2复合纳米纤维的可控合成。以罗丹明B为模拟污染物,考察了SnO2/TiO2复合纳米纤维的光催化性能,与纯TiO2纳米纤维相比光催化活性明显提高,初步探讨了光催化反应机理。     

LiAl_xMn_(2-x)O_4的制备及其在酸介质中的稳定性

采用沉淀法合成了系列掺Al尖晶石氧化物LiAl_xMn_(2-x)O_4(x=0,0.3,0.5,0.7,1.0)。通过X射线衍射(XRD)、能量色散谱(EDS)和扫描电子显微镜(SEM)等方法对其结构、成分和形貌进行了表征,并通过酸浸实验考察了不同组成和不同焙烧温度的LiAl_xMn_(2-x)O_4在弱酸性介质中的稳定性。结果表明当x为0.5,合成温度为850℃时,Al能最大程度地纳入尖晶石晶格,形成结晶致密、成分均匀的产物。同时,LiAl_(0.5)Mn_(1.5)O_4能较大程度地抑制Mn在弱酸条件下的溶出,而具有较低的Al溶出率和较高的Li溶出率。酸浸后LiAl_(0.5)Mn_(1.5)O_4仍保持尖晶石结构且形貌完整。     

尖晶石LiMn2O4纳米粉的合成 及其交流阻抗性能研究

以LiOH和电解二氧化锰(EMD)为原料,葡萄糖为还原剂,制备了粒径为200nm左右的球状尖晶石LiMn2O4纳米粒子,并用X射线衍射(XRD)和扫描电镜(SEM)对样品进行了结构和形貌的表征.在循环伏安测试(CV)峰电位下研究了该材料嵌脱锂相变过程中的交流阻抗(EIS)图谱,并提出一种新的等效电路对EIS图谱进行拟合...     

Multi-instrument characterization of HiPIMS and DC magnetron sputtered tungsten and copper films

In this work, copper and tungsten were sputtered onto silicon wafers by direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). The resulting films were characterized by energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and X-ray diffraction (XRD). By EDX and XPS, all the sputtered films showed only the expected metal peaks. By XPS, the surfaces sputtered by DCMS were richer in oxygen than those produced by HiPIMS. By AFM, the surfaces were quite smooth. The root mean square (RMS) roughness values are as follows: 0.83 nm (W, HiPIMS), 1.10 nm (W, DCMS), 0.85 nm (Cu, HiPIMS), and 1.78 nm (Cu, DCMS). By SEM, the HiPIMS films exhibited smaller grain sizes, which was confirmed by XRD. The crystallite sizes estimated by XRD are as follows: 4 nm (W, body-centered cubic, HiPIMS), 13 nm (W, body-centered cubic, DCMS), 7 nm (W, cubic, HiPIMS), 14 nm (W, cubic, DCMS), 25 nm (Cu, HiPIMS), and 35 nm (Cu, DCMS). By SE, the HiPIMS surfaces showed higher refractive indices, which suggested that they were denser and less oxidized than the DCMS surfaces.     

铂纳米空球的制备及其对甲醇氧化的电催化性能

以粒径为100nm的硒球作模板,在室温下批量合成了粒径约110nm、壳厚约5 nm的铂空球.采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、高分辨透射电子显微镜（HR-TEM）、选区电子衍射（SAED）、X射线衍射（XRD）、能量色散X射线谱（EDX）等检测技术表征了其形貌与结构;以甲醇为探针分子研究了铂纳米空球修饰玻碳电极对甲醇电氧化的催化性能.结果表明,由铂原子簇团构筑的多孔铂空球粒径均匀、分散性好、结构稳定、比表面积大、传质性能好,是甲醇氧化的理想催化材料.循环伏安（CV）结果表明:当甲醇氧化的电流密度0.10 mA·cm^-2,正扫时,铂纳米空球的氧化电位与实心铂纳米粒子及铂黑相比,分别负移了约110和64mV;负扫时,前者比后两者分别负移了约51与13 mV.经800圈循环伏安扫描后,正扫时,甲醇在铂纳米空球上氧化峰的电流密度为实心铂纳米粒子及铂黑上的13和15倍;负扫时,前者为后两者的19和38倍.表明铂纳米空球对甲醇氧化具有较好的催化活性和稳定性.     

Noble metal doped graphene nanocomposites and its study of photocatalytic hydrogen evolution

This work reports the deposition of platinum (Pt) nanoparticles on the surface of graphene nanosheet by a simple approach, using a microwave-assisted method. The photocatalytic activity has been investigated for hydrogen evolution. The hydrogen evolutions were attributed to graphene, due to its high photoelectron transport properties, and the Pt nanoparticles attached on the surface of graphene sheet, which act as reaction centers for H₂ evolution. The “as-prepared” composites were characterized by Brunauer Emmett Teller (BET) surface area measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectra (DRS). This work highlights the potential application of graphene-based materials in the field of energy conversion.     

Biosynthesis of silver nanocrystals by Bacillus licheniformis

The use of microorganisms for the synthesis of nanoparticles is in the limelight of modern nanotechnology. Using the bacterium Bacillus licheniformis, the biosynthesis of silver nanoparticles was investigated. These silver nanoparticles were characterized by means of UV-vis spectroscopy, scanning electron microscopy (SEM), electron diffraction spectroscopy (EDX) and X-ray diffraction (XRD). The nanoparticles exhibited maximum absorbance at 440 nm in UV-vis spectroscopy. The XRD spectrum of silver nanoparticles exhibited 2theta values corresponding to the silver nanocrystal. SEM micrographs revealed the formation of well-dispersed silver nanoparticles of 50 nm, and the presence of silver was confirmed by EDX analysis.     

Synthesis of a hybrid assembly composed of titanium dioxide nanoparticles and thin multi-walled carbon nanotubes using "click chemistry"

A hybrid assembly composed of thin multi-walled carbon nanotubes (t-MWCNT) and titanium dioxide (TiO(2)) has been prepared by using "click" chemistry for photocatalytic applications. TiO(2)-decorated t-MWCNT hybrids with anatase phase TiO(2) were obtained from the reaction of an azide moiety-containing TiO(2) with alkyne-functionalized t-MWCNTs. The hybrids were systematically characterized using Fourier transform infrared spectroscopic (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrum (EDX), and X-ray diffraction (XRD) measurements. The nanohybrid has been proved to be highly active and robust for photocatalytic degradation of methyl orange. The click coupling approach is a simple and convenient route to efficiently assemble TiO(2) on the surface of carbon nanotubes, and can be extended to obtain many other nanoparticle hybrids based on carbon nanotubes.     

Ag2S/Al2O3纳米复合物的水热合成及表征

采用水热技术结合煅烧的方法,成功制备了Ag2S/Al2O3纳米复合物。 通过SEM、EDX、XRD等测试技术对产品进行了表征,证明得到的产品是Ag2S/Al2O3纳米复合物;无孔Al2O3和多孔Al2O3作反应模板得到的复合物的形态和分布不同。