Papers by Keyword: HRTEM

Abstract: Nanoscale carbon tubes (also referred as CNTs) along with other nanostructures made from carbon could keep you amused as you waiting for your chance to participate in this nanotechnology. Research on carbon nanotubes has attracted an enormous amount of focus from researchers across the world for the significant function that it could have in the growing field of nanotechnology. The MLCNTs were made using these temperatures as the operational parameters using a fatty acid methyl ester formed from peanut oil as a precursor at a flow rate of 20 mL per hour in an environment comprised of argon. The intention of this research is to examine a usual green originator for the production of multiple layer carbon nanotubes (MLCNTs) using the methyl ester of a fatty acid of peanut oil at temperature that range from 725°C to 875°C with intervals of 75°C on Fe-Co assisted on Silica within an atmosphere of argon. The investigation will be concentrated on the production of MLCNTs on Fe-Co assisted on Silica. The as-grown carbon nanomaterials have been studied using SEM, HRTEM, XRD, and Raman spectroscopic research. We observed that the yield and diameter of the as-grown MLCNTs were not the same across the entire board for temperatures. The crystalline temperature of the CNTs climbed from 725 degrees Celsius to 800 degrees Celsius initially, and eventually it dropped from 800 degrees Celsius to 875 degrees Celsius. The temperature at which MLCNTs are created may have a bearing on the level of graphitization that they'll show.

Abstract: ZnO films were deposited by magnetron sputtering using RF power supply, in order to study the effect of substrates on quality of the prepared films. Then, growth of the ZnO films on thin AlN buffer layer and Si(100) substrates were characterized using different techniques. The surface morphology was investigated by means of scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The structural properties were investigated via X-ray diffraction (XRD) patterns, Rocking Curve as well as Pole figures. The ZnO films were textured and they had preferred orientation (002) and the crystallinity was better for ZnO/Si in the used growth conditions. The XRD results were confirmed by HRTEM. Optical properties were analyzed by photoluminescence (PL), as well as electrical characteristics were performed by C-V and I-V measurements. The dispersion orientation of these films, as indicated via the FWHM (rocking curves), is small for thin ZnO/Si. These results are considered as hopeful for piezoelectric applications.

Abstract: Bimetallic nanoparticles (BMNPs) of silver and gold are synthesized by eco- friendly green chemical procedure using leaf extract of Cocculus hirsutus. Under the experimental condition most individual silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) are spherical whereas silver-gold bimetallic nanoparticles (Ag-Au BMNPs) found cloudy and lost their individual shape. Ag-Au BMNPs formed by the co-reduction of Au(III) and Ag(I) ions in aqueous leaves extract solution where the extract act as both reducing and capping agent. NPs were characterized with the help of UV-Vis absorption spectroscopy, high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) analysis. UV-Vis spectroscopy exhibit surface plasmon absorption maxima at 435 and 540 nm for AgNPs and AuNPs respectively whereas surface plasmon resonance (SPR) maxima for Au-Ag bimetallic appeared in between the peaks corresponding to pure silver and gold at the same reaction conditions. X-ray diffraction analysis confirmed that crystalline nanoparticles (NPs) are face centered cubic structure. The synthesized bimetallic nanocomposites show stronger scavenging ability, around 67% and 75% on hydroxyl radical and superoxide radicals at the concentration of 400 µg/ml respectively, compared to the mono metallic AgNPs and AuNPs, indicating stronger antioxidant properties of Ag-Au BMNPs.

Abstract: A method for the identification of graphene materials in fibers by high-resolution transmission electron microscopy (HRTEM)-Energy Dispersive Spectroscopy (EDS) has been reported. Two ways to prepare samples are available, namely the dissolution extraction and the ultra-thin sectioning method. For samples prepared by any method, the graphene material in the fiber can be detected by the following steps. Firstly,the elemental composition of the microparticle is demonstrated by EDS. Secondly, the morphology of the particles in the fiber can be obtained by TEM, and the number of layers of graphene materials is able to observed directly from the edge of sheet.

Abstract: In this paper, red phosphorus successfully turned to black phosphorus by the mechanical ball milling method. The samples were analyzed by the X-ray diffraction (XRD) method and by high resolution transmission electron microscopy (HRTEM). The XRD result showed that the black phosphorus obtained had small crystal size and a small, amorphous, broadly diffused peak of red phosphorus. The HRTEM analysis showed that the grain size of most of the black phosphorus was small (about 3-5nm). The electron diffraction pattern and the d-spacing on HRTEM correspond well to the characteristic peaks of black phosphorus, such as {111}, {021} and {151}. In some areas, the grain size of black phosphorus was large (about 20-50nm) and contained many defects in crystals. This showed that initially, the amorphous red phosphorus turned into black phosphorus nanocrystals under the action of mechanical milling. Subsequently, the grains were refined and became tiny grains under the action of a large number of edge dislocations in the crystals. During analysis of the TEM, the small size crystals of black phosphorus were rapidly non-crystallized and seriously damaged by electron irradiation. Therefore only the big grains were left after 30 minutes of irradiation.

Abstract: A series of europium doped magnesium borotellurite glasses embedded with manganese nanoparticles (Mn₃O₄ NPs) of composition (59-x)TeO₂-30B₂O₃-10MgO-x1Eu₂O₃-1Mn₃O₄ with 0.5 ≤ x ≤ 1.5 mol % are prepared using melt quenching technique. The existence of broad hump in X-ray diffraction (XRD) pattern verifies the amorphous nature of glasses. The presence of Mn₃O₄ NPs with average diameter of ~11 nm and (1 0 3) lattice plane having 0.276 nm spacing in the glass matrix is confirmed by high resolution transmission electron microscope (HRTEM) image. The glass samples are excited under 390 nm excitation wavelength and the emission spectra are found to consist of four emission peaks centred at 587 nm, 610 nm, 651 nm and 700 nm assigned to the transition from ⁵D₀ →⁷F_J (J = 1, 2, 3, 4) states. The schematic energy level diagram is proposed. All results will be discussed with respect to the composition of Eu³⁺ ion.

Abstract: The mechanical destruction of the pyrophyllite structure and final ground products upon grinding with a laboratory planetary ball mill were investigated using high-resolution transmission electron microscope (HRTEM) coupled with selected area electron diffraction (SAED), field emission scanning electron microscope (SEM) and X-ray diffraction (XRD). Grinding produced a profound structural alteration, resulting in increasing amorphization. Increasing the intensity of grinding resulted in acceleration of the mechanically induced amorphization of the pyrophyllite structure. The pyrophyllite phase was transformed into its anhydride phase during the process of the prolonged grinding. Increasing the grinding intensity resulted in faster destruction of the pyrophyllite structure. The plate-like microcrystal exhibited the 2M-pyrophyllite crystal structure. The pyrophyllite anhydride phase was existed after grinding.

Abstract: The β-phase transforms to α′, α and α" within a range of temperature from the β-transus (T_β) to about 600°C, considering no external stress is applied. Two types of microstructure were obtained: acicular martensite when rapidly cooled and lamellar α/β when slowly cooled from the β phase field. The sequential transformation of β into α′, α-phase, α₂, and α" was revealed as peaks on the coefficient thermal expansion (CTE) curves, however, reversed transformations: α"→β, and α→β, were revealed by the DSC thermograms. The presence of β, α′, α, α₂ and α" was identified by means of XRD analysis and HRTEM.

Abstract: In order to better understand the morphology and properties of polymer nanocomposites it is necessary to conduct their characterization by Transmission Electron Microscopy (TEM). This work shows a technique through which the nanocomposite powder is mixed with a resin, and after cured, thin sections can be obtained by ultramicrotomy. Another technique presented in this work deals with the observation of clay powder in solution. In this work High Resolution Electron Microscopy (HRTEM) was used to obtain images of the nanocomposites and clay. Images with a high level of details were showed. Through the use of such techniques, it was possible to observe two types of clay morphology in polymer matrix and its distribution. The dimensions and hexagonal layers of the natural clay used as nanofiller for the nanocomposite were also observed. The X-ray Diffraction (XRD) was used to investigate the kaolinite and nanocomposite.

Abstract: Synchrotron white beam x-ray topography (SWBXT), synchrotron monochromatic beam x-ray topography (SMBXT), and high resolution transmission electron microscopy (HRTEM) studies have been carried out on stacking faults in PVT grown 4H-SiC crystal. Their fault vectors were determined by SWBXT to be 1/3<-1100>, 1/2<0001>, 1/6<-2203>, 1/12<4-403>, 1/12<-4403>. HRTEM studies reveal their similarity in stacking sequences as limited numbers of bilayers of 6H polytype structure. Simulation results of the two partial dislocations associated with the stacking faults in SMBXT images reveal the opposite sign nature of their Burgers vectors. A mechanism for stacking fault formation via 2D nucleation is postulated.