A systematic study of long-range ordered 3D-SBA-15 materials by electron tomography

The porous structure and the periodic array of cavities in ordered mesoporous materials with large, three-dimensionally arranged and interconnected pores is thoroughly described by combining electron tomography, small-angle X-ray diffraction, and nitrogen sorption techniques. We used the ability of the electron tomography to provide local three-dimensional information of a nano-object and compared the results to those of the other characterization techniques which furnish global information. We showed thus that the face-centered cubic (fcc) structure usually assigned to the FDU-12 materials is in fact an intergrowth of cubic and hexagonal close-packing structures. This agrees with small-angle X-ray scattering (SAXS) modeling, but for the first time a direct visualization of these stacking faults was achieved. Three-dimensional transmission electron microscopy (3D-TEM) provides also a direct and unique evidence of peculiar stacking defects ("z-shifted [111] areas"), as well as an estimate of their density, which have never been reported elsewhere. In addition, interstitial cavities were also observed, revealing the complex defective structure of this material. A direct observation of the nature of the connecting pores was also achieved for the first time, with a resolution limit of 2 nm. Finally, the characteristics of the porous network evidenced by 3D-TEM are used to explain and validate the results obtained by nitrogen sorption experiments.

Three-dimensional tomography reveals distinct morphological and optical properties of soot aggregates from coal-fired residential stoves in China

In this study, a 30 kW RF plasma reactor is used to synthesize metallic (Ni) and intermetallic (Mg2Ni) nanoparticles along with carbon-encapsulated Ni. The system was configured with injection probes at the top and bottom of the torch to facilitate the synthesis of compounds as well as core-shell particle structures. Materials used as precursors include methane, Ni, Mg, and pre-alloyed Mg2Ni powder. By feeding Ni together with methane, nickel nanoparticles encapsulated with 6-10 layers of graphite were produced. The core-shell particles and other samples collected were analyzed using X-ray diffraction and electron imaging techniques and were found to be spherical in shape and less than 100 nm in diameter.

The titanium oxide nanotubes have become a very attractive material with potential applications in biomedicine, photocatalysis, energy etc. Their properties depend mostly on morphology which is relatively easy to change by controlling the conditions of the anodization like the type of electrolyte used, the voltage and the time of anodization. There is a direct linear relation between the anodization voltage and the average diameter of the formed nanotubes, as the voltage increases the diameter of nanotubes also increases [1,2]. The possibility of the preparation of nanotubes with different size, shape and wall thickness leads to the control of their geometric surface area and specific surface area, which is an important parameter in the development of new substrates for example in heterogeneous catalysis. Nanotube surface functionalization with platinum nanoparticles is a way to fabricate active material for catalysis of oxidation reaction of methanol. Such nanostructured complex materials demand advanced methods for characterization and visualization of real structure, therefore application of TEM and electron tomography techniques is desired. In this work titania nanotubes were obtained by electrochemical oxidation of pure titanium at voltage of 10 and 25V, that resulted in creation of TiO 2 nanotubes with 40 and 110 nm in diameter, respectively. After anodization the heat treatment was performed at 450 o C for 1h to change amorphous structure of TiO 2 nanotubes into crystalline anatase structure. A suitable amount of Pt – 0.2 mg/cm 2 on the surface of the nanotubes was deposited using magnetron sputtering. FIB prepared specimens were analyzed in a Hitachi HD‐2700 dedicated STEM (Scanning Transmission Electron Microscopy). Fig. 1 shows cross‐section SEM images of TiO 2 nanotubes with 0.2 mg/cm 2 Pt deposit on the top. The platinum nanoparticles tend to choose the edges of TiO 2 nanotubes and side walls. A high amount of Pt fills the interior of the nanotubes as shown in Fig. 1b. As nanotubes diameter increases from 40 to 110 nm the depth of deposition into nanotubes also increases (Fig. 1c). Morphology of prepared structures was characterized by scanning transmission electron microscopy tomography. This method provides three‐dimensional structural information at nanoscale based on two dimensional projections acquired at different tilt angles. High angle annular dark field (HAADF) imaging was used for 2D projections. The results have shown distribution of platinum nanoparticles inside the nanotubes. The variations in platinum content introduced into different diameter nanotubes were also examined. Segmented volume of nanotubes was analyzed in terms of specific surface area and volume fraction.

Both light and electron microscopy have experienced exciting advances in the past few years, driven by the development of new imaging technologies and the ready availability of powerful computers and associated algorithms for visualization, analysis, and image restoration. The concomitant development of molecular genetic methods for engineering fluorescent molecules into proteins and for targeting indicator dyes to subcellular compartments has led to unprecedented opportunities for the study of dynamic processes and for correlating physiology and structure. Although the effective resolution of light microscopy has been increased through the use of optical sectioning and computational deblussing of images, the resolution of the light microscope is still not sufficient to address Inany issues of cell and tissue structure and protein localization. Electron microscopy has also undergone a quiet revolution, in particular high voltage electron microscopy, where the technique of electron tomography allows 3D reconstruction of relatively large structures such as neuronal spiny dendrites without the need for serial sectioning. In combination with light microscopy, high voltage EM and electron tomography provide a relatively straightforward method to bridge the resolution gap between light and electron microscopy. In this review, we discuss correlated 3D light and electron microscopy imaging of cells and tissues, including the adaptation of fluorescent dyes for electron microscopy imaging. (The J Histotechnol 23:261, 2000)

A new methodology to obtain magnetic information on magnetic nanoparticle (MNP) systems via electron tomography techniques is reported in this work. The new methodology is implemented in an under-development software package called Magn3t, written in Python and C++. A novel image-filtering technique that reduces the highly undesired diffraction effects in the tomography tilt-series has been also developed in order to increase the reliability of the correlations between morphology and magnetism. Using the Magn3t software, the magnetic shape anisotropy magnitude and direction of magnetite nanoparticles has been extracted for the first time directly from transmission electron tomography.

Hydrothermal treatment of erythromycin fermentation residue: Harmless performance and bioresource properties

Correlation of porosity types derived from NMR data and thin section image analysis in a carbonate reservoir

Three-dimensional (3D) structural analysis is essential to understand the relationship between the structure and function of an object. Many analytical techniques, such as X-ray diffraction, neutron spectroscopy, and electron microscopy imaging, are used to provide structural information. Transmission electron microscopy (TEM), one of the most popular analytic tools, has been widely used for structural analysis in both physical and biological sciences for many decades, in which 3D objects are projected into two-dimensional (2D) images. In many cases, 2D-projection images are insufficient to understand the relationship between the 3D structure and the function of nanoscale objects. Electron tomography (ET) is a technique that retrieves 3D structural information from a tilt series of 2D projections, and is gradually becoming a mature technology with sub-nanometer resolution. Distinct methods to overcome sample-based limitations have been separately developed in both physical and biological science, although they share some basic concepts of ET. This review discusses the common basis for 3D characterization, and specifies difficulties and solutions regarding both hard and soft materials research. It is hoped that novel solutions based on current state-of-the-art techniques for advanced applications in hybrid matter systems can be motivated.

In this paper, the mineral and pore structure characteristics of Longmaxi shale gas reservoir have been studied with a series of parallel experiments on core samples drilled from Jiaoshiba gas field, southern Sichuan Basin, China, including X-ray diffraction (XRD) tests, total organic carbon (TOC) analysis, field emission scanning electron microscopy (FE-SEM), low temperature nitrogen adsorption/desorption (LTNA), and nuclear magnetic resonance (NMR). The relations among TOC, mineralogical compositions and pore structure parameters, and comparison of pore size distribution (PSD) of shales obtained by LTNA and NMR are discussed. The results show that the Longmaxi shales are rich in organic matter, with an average content of 2.73%. The mineralogical compositions are dominated by quartz and clay minerals, with an average content of 43.72 and 36.32%, respectively. The TOC has strong positive correlations to the quartz and pyrite, but negative correlations to clay mineral. There are three types of pores, including organic pores, inorganic pores (inter-crystalline pores and intergranular pores), and microfractures (diagenetic shrinkage joints and organic evolution abnormal-pressure fracture), which can be seen from FE-SEM, with pore sizes following the order of organic pores <inorganic pores < micro-fractures. The organic matter and quartz have a positive influence on the specific surface (ranging from 7.27 to 14.705 m2/g) and total pore volume (ranging from 0.004 to 0.02 cm3/g), whereas clay minerals have a negative effect on the specific surface and total pore volume. Compared with LTNA, the NMR can better reveal pores, indicating pore size ranging from smaller than 1 nm to several tens of micrometers. The PSDs acquired from NMR present tri-modal distribution when TOC content is higher than 2.5% and clay mineral content lower than 40%. On the contrary, the PSDs present bi-modal distribution when TOC content is lower than 2.5% and clay mineral content higher than 40%.

Crystallization of synthetic hydrotalcite under hydrothermal conditions

Investigation on pore structure characteristics of ultra-tight sandstone reservoirs in the upper Triassic Xujiahe Formation of the northern Sichuan Basin, China

Assessing shale gas reservoir potential using multi-scaled SEM pore network characterizations and quantifications: The Ciñera-Matallana pull-apart basin, NW Spain

Integrating in situ deformation and electron tomography (ET) techniques allows us to visualize the materials’ response to an applied stress with nanometer spatial resolution. The capability of structural, chemical, and morphological characterization in three-dimension real time and at sub-microscopic levels alleviates several persistent problems of two-dimensional imaging such as the projection effect and postmortem appearance. On the other hand, implementing deformation mechanism introduces additional experimental constraints that could influence the accuracy of the reconstructed volumes in a different way. To materialize quantitative and statistically relevant microstructure interpretation by time-resolved ET, we evaluated several key parameters such as angular tilt range, tilt increment, and reconstruction algorithms to characterize their influences on the accuracy of size and morphology reproducibility.

Evaluation of Hydrothermal Treatment of Empty Fruit Bunch for Solid Fuel and Liquid Organic Fertilizer Co-Production