The high efficiency of solid oxide fuel cells with La0.8Sr0.2MnO3−δ (LSM) cathodes working in the range of 800–1000 °C, rapidly decreases below 800 °C. The goal of this study is to improve the properties of LSM cathodes working in the range of 500–800 °C by the addition of YFe0.5Co0.5O3 (YFC). Monophasic YFC is synthesized and sintered at 950 °C. Composite cathodes are prepared on Ce0.8Sm0.2O1.9 electrolyte disks using pastes containing YFC and LSM powders mixed in 0:1, 1:19, and 1:1 weight ratios denoted LSM, LSM1, and LSM1, respectively. X-ray diffraction patterns of tested composites reveal the presence of pure perovskite phases in samples sintered at 950 °C and the presence of Sr4Fe4O11, YMnO3, and La0.775Sr0.225MnO3.047 phases in samples sintered at 1100 °C. Electrochemical impedance spectroscopy reveals that polarization resistance increases from LSM1, by LSM, to LSM2. Differences in polarization resistance increase with decreasing operating temperatures because activation energy rises in the same order and equals to 1.33, 1.34, and 1.58 eV for LSM1, LSM, and LSM2, respectively. The lower polarization resistance of LSM1 electrodes is caused by the lower resistance associated with the charge transfer process.
In this paper, the regioselective reactions of kaolinite and methoxy-modified kaolinite (MeO-Kaol), methanol-expanded kaolinite, with octadecyltrimethylammonium salts are compared. This study mainly concerns the reactions of kaolinite or MeO-Kaol with octadecyltrimethylammonium chloride (C18TAC) in methanol and the subsequent exhaustive washing of the resultant products with ethanol. X-ray diffraction patterns of the products reveal no intercalation of C18TAC between pristine kaolinite layers. Additionally, intercalation and subsequent deintercalation of C18TAC proceed in the product using MeO-Kaol. In the Fourier-transform infrared spectra, the intensities of CH2 stretching bands of the product prepared using MeO-Kaol drastically increase compared to those using kaolinite. In addition, CH2 stretching bands of the product using kaolinite are hardly observed without enlarging the spectrum. The product using MeO-Kaol also displays mass loss in the range of 200–300 °C in the thermogravimetric curve and a nitrogen content with 0.15 mass% estimated using the CHN analysis. These results therefore demonstrate an increase in the available reactive edges in the layered crystal material following an expansion of the stacked layers.
AbstractA raw electron backscatter diffraction (EBSD) signal can be empirically decomposed into a Kikuchi diffraction pattern and a smooth background. For pattern indexing, the latter is generally undesirable but can reveal topographical, compositional, or diffraction contrast. In this study, we proposed a new background correction method using polynomial fitting (PF) algorithm to obtain clear Kikuchi diffraction patterns for some applications in nonconductive materials due to coating problems, at low accelerated voltage and at rough sample surfaces and for the requirement of high pattern quality in HR-EBSD. To evaluate the quality metrics of the Kikuchi patterns, we initially used three indices, namely, pattern quality, Tenengrad variance, and spatial–spectral entropy-based quality to detect the clarity, contrast, and noise of Kikuchi patterns obtained at 5 and 15 kV. Then, we examined the performance of PF method by comparing it with pattern averaging and Fourier transform-based methods. Finally, this PF background correction is demonstrated to extract the background images from the blurred diffraction patterns of EBSD measurements at low kV accelerating voltage and with coating layer, and to provide clear Kikuchi patterns successfully.
AbstractThis study reports on the physical, mechanical, mineralogical and geochemical analysis carried out on four lateritic hardpan specimens from quarries in the Bamendjou area in the Western Region of Cameroon using common prescribed procedures. The results indicate that values of the bulk density, specific gravity, total and open porosities are very variable from one specimen to another. Meanwhile, the value of the compressive strengths of both the dry and immersed specimens were also very variable from one specimen to another, with the F2 and F1 specimens having higher values than the A1 and A2 specimens. All the specimens immersed in water recorded lower compressive strengths than the dry specimens. The flexural strengths also varied from one sample to another, with the F2 specimen having the highest resistance. The X-ray diffraction patterns reveal that the major peaks were assigned to gibbsite, goethite, and hematite, while the minor peaks were assigned to kaolinite and anatase. The mineralogy and geochemistry influenced the physical and mechanical properties, with the iron rich specimens having higher values in both the physical and mechanical properties than the alumina rich specimens. The results of the compressive strengths obtained were higher than (1–4) MPa obtained in Burkina Faso and India where they have been using latertic blocks for construction. Thus the hardpans of Bamendjou can also be exploited for building purposes conveniently.
The Geometric Algebra formalism opens the door to developing a theory
upgrading conventional quantum mechanics. Generalizations, stemming from
implementation of complex numbers as geometrically feasible objects in
three dimensions; unambiguous definition of states, observables,
measurements bring into reality clear explanations of conventional weird
quantum mechanical features, particularly the results of double split
experiments where particles create diffraction patterns inherent to wave
diffraction. This weirdness of the double split experiment is milestone
of all further difficulties in interpretation of quantum mechanics.
Composite of polyaniline-MgCl has been synthesized using oxidative polymerization method. Synthesized samples were characterized for structural analysis using FTIR and XRD. Morphological studies were carried by SEM micrographs. Current-Voltage (I-V) properties are obtained through Kiethly source meter. FTIR spectrum of polyaniline-MgCl composite indicates all the characteristic peaks of polyaniline. X-ray diffraction patterns represented the amorphous nature of polyaniline-MgCl composite. SEM micrographs confirmed the presence of MgCl particles in polyaniline matrix. I-V characteristics have shown the ohmic type behavior of polyaniline and polyaniline-MgCl composite.
This contribution is devoted to discussion of questions related to the influence of a possible contribution from a bulk material on the lineshape of elastic peaks observed in diffraction experiments at neutron and / or X-ray radiation scattering on nanoporous matrices containing substances embedded into their porous space (channels). The proposed algorithm permits to estimate the input of massive component into diffraction peaks using the analysis of the experimentally observed distortions of the lineshape of the Bragg peaks. This preliminary analysis greatly simplifies the profile analysis of nanocomposite diffraction patterns, especially for molecular sieves based on powders of SBA-15, MCM-41, MCM-48, etc. types.
In this study, chitosan was extracted from shrimp shells by demineralization and deproteination processes. The extracted chitosan was used to modify the layered double hydroxide and used as an adsorbent for the removal of congo red from aqueous solutions. Composites were successfully synthesized using M2+/Al (M2+ = Zn, Mg, Ni) and chitosan (CH) and the samples obtained were characterized using XRD and FTIR. The X-ray diffraction (XRD) pattern appeared at the layered double hydroxide peak of 2? = 11.63°; 23.00°; 35.16°; and 61.59° and chitosan at 2? = 7.93° and 19.35. The composite appearing in the layered double hydroxide and chitosan indicated that the composite material has been successfully synthesized. The XRD diffraction patterns of Zn/Al-CH, Ni/Al-CH, and Mg/Al-CH showed low crystallinity. The Fourier Transform Infrared (FTIR) spectra verifying absorption spectrum showed the presence of two bands at 3448 cm-1, 1382cm-1 characteristic to both chitosan and LDH. Adsorption of Congo Red (CR) followed the pseudo-second-order and Langmuir isotherm models. The adsorption capacities of Zn/Al-CH, Ni/Al-CH, and Mg/Al-CH were 181.818 mg/g, 227.273 mg/g, and 344.828 mg/g, respectively. The layered double hydroxide-chitosan composite adsorption was endothermically characterized by positive enthalpy and entropy values. On the other hand, the adsorption spontaneously was characterized by a negative Gibbs free energy value. The composites in this study were formed from LDH modified from chitosan extracted from shrimp shells to form Zn/Al-CH, Ni/Al-CH, and Mg/Al-CH. The results of the characterization showed a number of characteristics that resembled the constituent materials in the form of LDH and chitosan. After being applied as an adsorbent to absorb Congo red dye, it then showed the most effective results using Mg/Al-CH adsorbent with an adsorption capacity of 344.828 mg/g.
In the quasi-binary system CaNi2-MgNi2 solid-solutions CaxMg1−xNi2 (0 ≤ x ≤ 1) were prepared from the elements. They crystallize in the hexagonal Laves phase type (MgNi2, C36) for x ≤ 0.33 (P63/mmc, a = 482.51(7) pm, c = 1582.1(3) pm for x = 0, a = 482.59 (3), c = 1583.1(1) for x = 0.33) and in the cubic Laves phase type (MgCu2, C15) for 0.33 < x (Fd−3m, a = 697.12(3) pm for x = 0.5, a = 705.11(2) pm for x = 0.67, a = 724.80(2) pm for x = 1). After hydrogenation in an autoclave the X-ray diffraction patterns changed completely. Reflections assigned to CaNiH3, and Ni and Rietveld refinement confirmed this. The hydrogenation properties of CaxMg1−xNi2 (0 ≤ x ≤ 1) compounds were also studied in situ by X-ray powder diffraction. In situ X-ray powder diffraction of CaxMg1−xNi2 (0 ≤ x ≤ 1) compounds under 0.3 MPa hydrogen gas flow (15 sccm), data collected on a Rigaku SmartLab diffractometer in an Anton Paar XRK 900 Reactor Chamber using Cu-Kα1 radiation. Scanning electron microscopy and EDX spectroscopy confirmed the entitled materials and elemental composition, respectively. From the Transmission electron microscopy and Selected area electron diffraction concluded that the CaxMg1−xNi2 (0 ≤ x ≤ 1) compounds were crystalline.