Powder X-ray diffraction measurements

Powder X-ray diffraction and SAXS were employed here to explore the microstructure of hard carbon samples with high capacities. Powder X-ray diffraction measurements were made on all the samples listed in Table 4. We concentrate here on sample BrlOOO, shown in Fig. 27. A weak and broad (002) Bragg peak (near 22°) is observed. Well formed (100) (at about 43.3°) and (110) (near 80°) peaks are also seen. The sample is predominantly made up of graphene sheets with a lateral extension of about 20-30A (referring to Table 2, applying the Scherrer equation to the (100) peaks). These layers are not stacked in a parallel fashion, and therefore, there must be small pores or voids between them. We used SAXS to probe these pores. 

The ferric oxide, hematite, used in the present work was a high purity powder reagent with a BET surface area of 27 m2/g 30 mg was employed in each run. Some measurements were made on hematite calcined in air to see the effects of sintering the surface on the chemical structure of the adsorbed metal ions. The hematite samples were checked by Mossbauer absorption and powder X-ray diffraction measurements. The Mossbauer absorption spectra consisted of a magnetic sextet with no superparamagnetic component due to fine particles ( ). 

We can learn the structural change in the crystals during topochemical polymerization by powder X-ray diffraction measurements. X-ray diffraction profiles continuously changed during the polymerization of 1 under the irradiation of an X-ray beam (Fig. 5) [51]. The reflections shifted and approached the reflection position of the polymer. This suggests that the polymerization... 

For each synthesis, a reactant mixture was placed in a stainless autoclave with an agitator. The crystallization was carried out in a temperature range 90°-200°C for 20-72 h. The solid product was filtered, washed and dried. Zeolite was identified by powder X-ray diffraction measurement. Chemical analysis was conducted by atomic adsorption spectrometry. 

Catalyst surface areas were measured using the multi-point BET method on a Carlo-Erba Ins. Sorpty 1750. Before the measurements, the samples were heated under dynamic vacuum at 573 K for 1 h in order to remove adsorbed water and impurities. Measurements were made at liquid nitrogen temperature with nitrogen as the adsorbate gas. Powder X-ray diffraction measurements were performed on a Siemens Model D-500 diffractometer with Co Kc monochromatic radiation (X = 1.78901 A) and the high resolution electron microscopy was carried out on a Topcon EM-002B microscope. To prevent artefacts no solvents were used in the preparation and mounting of samples for HRTEM. 

Results from powder X-ray diffraction measurements indicated that the interlayer spacing of vermiculite did not change during the reaction. This implies that the interlayer region is too narrow to accommodate the reactants and only Lewis acid sites on the external surfaces, probably Fe3+ cations, are responsible for catalysing the reaction. 

Particle size analysis was carried out on a Horiba dynamic laser scattering particle size analyser. Powder X-ray diffraction measurements were performed on a Siemens D500 diffratometer with a monochromated Cu Ka radiation source. SEM analysis was done using a Zeiss Ultra55 Electron Microscope. The gas tightness of non reduced half cells (substrate, anode, and electrolyte, dimensions ... 

UV/vis absorption spectra were recorded on a Shimadzu UV-3100 spectrophotometer. Powder X-ray diffraction measurements were carried out on a Scintag XDS-2000 powder diffraction system. Transmission electron microscopy (TEM) images were obtained on Hitachi 7000 and Hitachi HF-2000 TEM systems. 

The CN valence frequencies of the bridged compounds shift to higher energy as compared with the mononuclear complexes M [PcM(CN)2]. This increase in CN valence frequencies is a good indication for the presence of a cyano bridge in [PcM(CN)]n [129]. Powder X-ray diffraction measurements give evidence... 

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