Search results for "Scanning electron microscope"

Synthesis of new molybdenum–tungsten, vanadium–tungsten and vanadium–molybdenum–tungsten oxynitrides from freeze-dried precursors

2004

Abstract Interstitial molybdenum–tungsten, vanadium–tungsten and vanadium–molybdenum–tungsten oxynitrides in the solid solution series Mo1−zWz(OxNy) and V1−zWz(OxNy) (z=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1), and V1−u−zMouWz(OxNy) (u, z=0.2, 0.33, 0.4, 0.6; u+z

V2O5 nanowires with an intrinsic iodination activity leading to the formation of self-assembled melanin-like biopolymers

2011

V2O5 nanowires act as biomimetic catalysts resembling vanadium haloperoxidases (V-HPO). The nanowires display iodinating activity as confirmed by a colorimetric assay using thymol blue (TB), UV/Vis spectrophotometry and mass spectrometry (FD-MS). In the presence of dopamine these nanowires catalyze the fast and efficient synthesis of melanin-like biopolymers under mild conditions (aqueous solution, neutral pH and room temperature). The resulting melanin-like biopolymer obtained by the V2O5 nanowire catalysts was characterized by scanning electron microscopy (SEM), X-ray diffraction, UV-Vis, FT-IR and electric conductivity resembling the natural biopolymer both in its chemical and morphologi…

Consolidation and protection by nanolime: recent advances for the conservation of the graffiti, Carceri dello Steri Palermo and of the 18th century l…

2014

Abstract Nanolime dispersed in 2-propanol was extensively used for the consolidation of wall paintings. The knowledge of the advances of this methodology dealing with all the possible effects associated with the nanolime new material in conservation is fundamental to assess and improve the technique. In this paper, four different dispersions of Ca(OH) 2 nanoparticles were characterised by Small Angle X-rays Scattering technique (SAXS) and Transmission Electron Microscopy (TEM) in order to achieve information on size, shape, polydispersity, agglomeration, and crystal structure (by SAED patterns) of the particles. Once characterised, the dispersions were tested in two different case studies, …

The Electrical Properties of Ba1-ySryZrxTi1-xO3Solid Solution

2011

A lead-free solid solution Ba0.80Sr0.20Ti0.75Zr0.25O3 was prepared by a conventional technology. The structure and morphology of investgated samples were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The studies of electric conductivity were performed depending on temperature and frequency of electric measuring field. The activation energy was calculated from the Arrhenius plots.

Effect of Zr4+Doping on the Electrical Properties of BaTiO3Ceramics

2011

The BaZrxTi1-xO3 for 0⩽x⩽15 ceramics were prepared by a conventional solid state reaction method and were determined by an X-ray diffraction (XRD) and scanning electron microscopy (SEM) for crystallographic, surface morphological and compositional studies. A single phase with perovskite structure was identified in the samples at room temperature. No significant impurities were detected in an EDS spectrum and the samples are in good stoichiometric ratio. The temperature dependence of electric conductivity was evaluated in the temperature range from 300 to 550 K for a selected frequency by a HP4284 LCR meter. The activation energy was calculated from the Arrhenius plots.

Environmental scanning electron microscopy (ESEM) as a new technique to determine the ice nucleation capability of individual atmospheric aerosol par…

2007

Abstract Heterogeneous ice nucleation on synthetic silver iodide, natural kaolinite and montmorillonite particles via condensation, freezing and deposition modes was studied by environmental scanning electron microscopy (ESEM) in the temperature range of 250–270 K. By increasing the H2O pressure in the sample chamber at constant temperature, ice formation can be studied in situ and can be related to the chemical composition of the particles that can be determined simultaneously. For silver iodide and kaolinite, supersaturation values of first ice formation are in good agreement (1–2% absolute) with diffusion chamber experiments. For both substances, threshold temperatures for the condensati…

Pore-space characterization of an altered tonalite by X-ray computed microtomography and the14C-labeled-polymethylmethacrylate method

2012

[1] The structure of geological materials strongly affects migration processes that take place in them and are also important in their weathering and alteration processes. Further information of that structure will also be important for many applications that involve geological materials. The emphasis of this study was thus to characterize the pore structure and porosity of altered tonalite by combining different measuring techniques: X-ray tomography, the14C-polymethylmethacrylate method, electron microscopy, and argon pycnometry. Intragranular porosities were determined using chemical staining of rock surfaces. Three-dimensional distributions of minerals and porosities were evaluated with…

2017

Abstract. Eleven particle samples collected in the polar stratosphere during SOLVE (SAGE III Ozone loss and validation experiment) from January until March 2000 were characterized in detail by high-resolution transmission and scanning electron microscopy (TEM/SEM) combined with energy-dispersive X-ray microanalysis. A total of 4202 particles (TEM  =  3872; SEM  =  330) were analyzed from these samples, which were collected mostly inside the polar vortex in the altitude range between 17.3 and 19.9 km. Particles that were volatile in the microscope beams contained ammonium sulfates and hydrogen sulfates and dominated the samples. Some particles with diameters ranging from 20 to 830 nm were re…

Individual-particle analysis of airborne dust samples collected over Morocco in 2006 during SAMUM 1

2011

During the course of SAMUM 1 in May and June 2006, airborne samples were collected in southern Morocco at altitudes between 830 and 3340 m above ground. We analysed approximately 22 500 particles of 1–30 μm by automated individual-particle analysis with a scanning electron microscope (SEM) and an energy-dispersive X-ray (EDX) analyser. The major difference between samples is due to the presence and amount of chlorine- and sulphur-bearing particles, pointing to a varying maritime influence and to different degrees of aging. In contrast, the desert dust component is very homogeneous independent of altitude, activated local source area, and dust storm intensity, implying very fast mixing of th…

Surface spectroscopic study of the corrosion of ultrathin57Fe-evaporated and Langmuir-Blodgett films in humid SO2 environments

2000

Integral conversion electron Mossbauer spectroscopy (ICEMS), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and scanning electron microscopy (SEM) have been used to carry out a comparative study of the corrosion resistance against humid SO2-aggressive environments of ultrathin 57Fe films. These films, having a thickness ≤ 2.5 nm, have been prepared by evaporation of 57Fe under vacuum and by 57Fe coating by a Langmuir–Blodgett (LB) technique on SiO2/Si wafers. The results have shown that the corrosion resistance of the evaporated films is similar to that of massive Fe. However, the LB films show a remarkably higher corrosion resistance. Thus, although the Fe films …