Search results for "energy [jet]"
showing 10 items of 1760 documents
Update on desiccant wheel model
2004
This short communication presents the update on the desiccant wheel models, developed earlier by the present authors. It is to be mentioned here that the psycrometric model presented earlier (Int. J. Energy Res., 2003; 27:17) is valid only for the desiccant wheel running with identical volume air-flows in supply and regeneration sides. However, when system runs with volume air flow ratio between supply and regeneration side (α), different from 1 (one), the model need further modifications. In the present work, correction factors were developed and incorporated in order to update the earlier model for predicting correctly the temperature and humidity of processed air at the outlet of desicca…
An experimental investigation on the poor hydrogen sorption properties of nano-structured LaNi5 prepared by ball-milling
2011
Abstract Nano-structured LaNi5 hydrogen storage materials prepared by ball-milling is analysed using differential scanning calorimetry (DSC) and x-ray photoelectron spectroscopy (XPS). DSC results indicate a partial elimination of defects at 500 °C in a more efficient way for the short-time ball-milled powders compared to the long-time ball-milled ones. XPS results show almost no change in the core-level electronic structure for La and Ni of LaNi5 in the bulk and the nano-structured forms, but gives an indication that the self-restoring mechanism of the active surface observed in the bulk sample (Siegmann et al. Phys. Rev. Lett. 40, 972) may not be occurring in the nano-powders. Results fro…
Using Electron Diffraction to Solve the Crystal Structure of a Laked Azo Pigment
2009
The structure of the ζ phase of Pigment Red 53:2 was solved using electron diffraction data. The unit cell determination appeared to be more complicated due to twinning of the crystals. A series of...
The Instability of the NbTe2 Surface Structure
2002
Low energy electron diffraction from clean NbTe 2 surfaces shows very diffuse reflections. The effect is attributed to an anisotropic heating of the irradiated Te-Nb-Te surface layer. Diffraction patterns for electron energies below 90 eV correspond to an overlapped contribution from numerous domains, belonging to three orientational variants. Electrons of higher energies stabilize the parent high-temperature CdI 2 structure. A similar effect is observed during scanning tunneling microscopy, where the expected surface corrugation is usually lost for tunneling currents of a few ten nA.
Transversal thermovoltages of (1 1 9) Bi2Sr2CaCu2O8+δ thin films on vicinal (1 1 0) SrTiO3 substrates
1997
Abstract Biaxial textured (1 1 9) oriented Bi 2 Sr 2 CaCu 2 O 8+δ thin films were fabricated by DC-Magnetron sputtering on vicinal (1 1 0) SrTiO 3 substrates. The crystal orientation and stochiometry of the films were obtained from precise X-ray diffraction measurements in four-circle geometry. According to anisotropic transport measurements, the superconducting transition temperature is approximately 47 K and the normal state resistivities along two perpendicular paths differ by a factor of 13.5. Transversal thermoelectric effects were investigated by measuring thermovoltages transverse to temperature gradients parallel to the surface normal induced by pulsed laser irradiation. At room tem…
Controlling the Formation of Sodium/Black Phosphorus IntercalationCompounds Towards High Sodium Content
2021
The solid-state synthesis of pure sodium-black phosphorus intercalation compounds (Na-BPICs) has been optimized in bulk for two stoichiometric ratios. Specifically, in-situ X-Ray diffraction (XRD) allowed the precise identification of the optimal temperature range for the formation of Na-BPICs: 94°C–96°C. Moreover, as the undesired formation of Na3P takes place at this very same range, we succeeded in introducing a new synthetic route based on a fast-thermal ball milling implementation that results in the bulk production of BPIC without Na3P in 9 out of 10 cases. Finally, by combining XRD, Raman spectroscopy, and DFT calculations we developed a new structural model for Na-based BPICs showin…
Electron diffraction, X-ray powder diffraction and pair-distribution-function analyses to determine the crystal structures of Pigment Yellow 213, C23…
2009
The crystal structure of the nanocrystalline alpha phase of Pigment Yellow 213 (P.Y. 213) was solved by a combination of single-crystal electron diffraction and X-ray powder diffraction, despite the poor crystallinity of the material. The molecules form an efficient dense packing, which explains the observed insolubility and weather fastness of the pigment. The pair-distribution function (PDF) of the alpha phase is consistent with the determined crystal structure. The beta phase of P.Y. 213 shows even lower crystal quality, so extracting any structural information directly from the diffraction data is not possible. PDF analysis indicates the beta phase to have a columnar structure with a si…
Cooperative atomic motion probed by ultrafast transmission electron diffraction
2015
In numerous solids exhibiting broken symmetry ground states, changes in electronic (spin) structure are accompanied by structural changes. Femtosecond time-resolved techniques recently contributed many important insights into the origin of their ground states by tracking dynamics of the electronic subsystem with femtosecond light pulses. Moreover, several studies of structural dynamics in systems with periodic lattice modulation (PLD) were performed. Since intensities of the super-lattice diffraction peaks are in the first approximation proportional to the square of the PLD amplitude, their temporal dynamics provides access to cooperative atomic motion. This process takes place on a fractio…
The role of electron diffraction in zeolite structure determination
2006
Because electron diffraction can sample individual microcrystals, it is clear that this single crystal method can facilitate, in at least two ways, structure determination for inorganic materials, such as zeolites, that are preferentially microcrystalline. First, in a qualitative application, three-dimensional tilts of individual small crystals, to map the reciprocal lattice, greatly facilitates unit cell and space group determination when powder diffraction indexing programs fail. If incoherent multiple scattering leads to violation of systematic absences, these absences can be restored by collection of precession diffraction patterns based on the Vincent-Midgley method [1], as demonstrate…
Automated electron diffraction tomography - a new tool for nano crystal structure analysis
2011
Automated electron Diffraction Tomography (ADT) comprises an upcoming method for “ab intio” structure analysis of nano crystals. ADT allows fine sampling of the reciprocal space by sequential collection of electron diffraction patterns while tilting a nano crystal in fixed tilt steps around an arbitrary axis. Electron diffraction is collected in nano diffraction mode (NED) with a semi-parallel beam with a diameter down to 50 nm. For crystal tracking micro-probe STEM imaging is used. Full automation of the acquisition procedure allowed optimisation of the electron dose distribution and therefore analysis of highly beam sensitive samples. Cell parameters, space group and reflection intensitie…