Synthesis, and crystal and electronic structure of sodium metal phosphate for use as a hybrid capacitor in non-aqueous electrolyte

Energy storage devices based on sodium have been considered as an alternative to traditional lithium based systems because of the natural abundance, cost effectiveness and low environmental impact of sodium. Their synthesis, and crystal and electronic properties have been discussed, because of the importance of electronic conductivity in supercapacitors for high rate applications. The density of states of a mixed sodium transition metal phosphate (maricite, NaMn1/3Co1/3Ni1/3PO4) has been determined with the ab initio generalized gradient approximation (GGA)+Hubbard term (U) method. The computed results for the mixed maricite are compared with the band gap of the parent NaFePO4 and the electrochemical experimental results are in good agreement. A mixed sodium transition metal phosphate served as an active electrode material for a hybrid supercapacitor. The hybrid device (maricite versus carbon) in a nonaqueous electrolyte shows redox peaks in the cyclic voltammograms and asymmetric profiles in the charge-discharge curves while exhibiting a specific capacitance of 40 F g(-1) and these processes are found to be quasi-reversible. After long term cycling, the device exhibits excellent capacity retention (95%) and coulombic efficiency (92%). The presence of carbon and the nanocomposite morphology, identified through X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) studies, ensures the high rate capability while offering possibilities to develop new cathode materials for sodium hybrid devices.

Efficient and practical synthesis of modular chiral beta-organochalcogeno amines, ArYCH2CH(R)NH2, and single crystal structures of (S) - MsOCH2CH(Bz)NH3+ center dot Cl- and (R)-MsOCH2CH(Ph)NH3+ center dot Cl-

Modular chiral I3-organochalcogeno amines, ArYCH2CH(R)NH2 (4a-4g) where R = Me, Bz, Ph; and ArY = PhS, BzSe and 4-MeOC6H4Te respectively have been synthesized and characterized. Compounds 4a-4g were synthesized (Method II) from chiral aminoalkyl 13-methanesulfonate hydrochlorides, MsOCH2CH(R)NH3+ center dot Cl- (2a-2c) through nucleophilic displacement of MsO- with organochalcogenolate (ArY-). In another attempt (Method I) chiral beta-organotelluro amines (4a-4c) were prepared by deprotection of chiral N-boc I3-organotelluro amides, 4-MeOC6H4TeCH2CH(R)NH-Boc (3a-3c), which in turn, 13,-,1 were made from chiral N-boc 13-methanesulfonate amides (la-lc) and ArTeNa. 1H, and FTIR spectra of all the compounds (3a-3c and 4a-4g) were characteristic. The composition of 3a-3c was determined by elemental analysis. The a]TD values of 3b-3c and 4a-4g were determined. The single crystal structures of (S)-2b and (R)-2c were determined by X-Ray diffraction studies. Both (S)-2b and (R)2c were crystallized in orthorhombic system and the Flack parameter x was found 0.08(12) and 0.00(2) respectively. The crystal of (S)-2b contain two asymmetric units with gauche (A) and staggered (B) conformations. There are NH Cl-, NH-O and CH-O intra and intermolecular secondary interactions in (S)-2b and (R)-2c resulting in supramolecular structures. (C) 2015 Elsevier By. All rights reserved.

Microhardness Studies of Vapour Grown Tin (II) Sulfide Single Crystals

Earth abundant tin sulfide (SnS) has attracted considerable attention as a possible absorber material for low-cost solar cells due to its favourable optoelectronic properties. Single crystals of SnS were grown by physical vapour deposition (PVD) technique. Microindentation studies were carried out on the cleaved surfaces of the crystals to understand their mechanical behaviour. Microhardness increased initially with the load, giving sharp maximum at 15 g. Quenching effect has increased the microhardness, while annealing reduced the microhardness of grown crystals. The hardness values of as-grown, annealed and quenched samples at 15 g load are computed to be 99.69, 44.52 and 106.29 kg/mm(2) respectively. The microhardness of PVD grown crystals are high compared to CdTe, a leading low-cost PV material. The as-grown faces are found to be fracture resistant.

Crystal structure of a tripeptide containing aminocyclododecane carboxylic acid: a supramolecular twisted parallel -sheet in crystals

The crystal structure of a tripeptide Boc-Leu-Val-Ac(12)c-OMe (1) is determined, which incorporates a bulky 1-aminocyclododecane-1-carboxylic acid (Ac(12)c) side chain. The peptide adopts a semi-extended backbone conformation for Leu and Val residues, while the backbone torsion angles of the C-,C--dialkylated residue Ac(12)c are in the helical region of the Ramachandran map. The molecular packing of 1 revealed a unique supramolecular twisted parallel -sheet coiling into a helical architecture in crystals, with the bulky hydrophobic Ac(12)c side chains projecting outward the helical column. This arrangement resembles the packing of peptide helices in crystal structures. Although short oligopeptides often assemble as parallel or anti-parallel -sheet in crystals, twisted or helical -sheet formation has been observed in a few examples of dipeptide crystal structures. Peptide 1 presents the first example of a tripeptide showing twisted -sheet assembly in crystals. Copyright (c) 2016 European Peptide Society and John Wiley & Sons, Ltd.

Growth mechanism of the interdiffusion zone between platinum modified bond coats and single crystal superalloys

Pt-modified beta-NiAl bond coats are applied over the superalloys for oxidation protection in jet engine applications. However, as shown in this study, it also enhances the growth of the interdiffusion zone developed between the bond coat and the superalloy along with brittle precipitates. Location of the Kirkendall plane indicates that a precipitate free sublayer grows from the bond coat, whereas another sublayer grows from the superalloy containing very high volume fraction of precipitates. With increasing Pt content, thickness of both the sublayers increases because of an increase in diffusion rates of the components. Quantitative electron probe microanalysis indicates high concentration of refractory components in the precipitates. Transmission electron microscopy shows that Rene N5 superalloy produces TCP phases mu and P, whereas CMSX-4 superalloy produces mu and sigma in the interdiffusion zone. With increasing Pt content in the bond coat, the average size of the precipitates decreases when coupled with Rene N5. Precipitates become much finer when the same bond coats are coupled with CMSX-4. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

CuIn1-xAlxSe2 Thin Films Grown by Co-Sputtering and Modified Selenization: Application in Flexible Solar Cells

Thin films of CuIn1-xAlxSe2 (CIAS) were grown on the flexible 10 micrometer thin stainless steel substrates, by dc co-sputtering from the elemental cathodes, followed by annealing with modified selenization. CuInAl alloyed precursor films were selenized both by noble gas assisted Se vapor transport in a tubular furnace and vacuum evaporation of Se in an evaporation chamber. CIAS thin films were optimized for better adhesion. X-ray diffraction, scanning electron microscopy, and UV-visible absorption spectroscopy were used to characterize the selenized films. The composition of CIAS films was varied by substituting In with Al in CuInSe2 (CIS) from 0 <= x <= 0.65 (x = Al/Al+In). Lattice parameters, average crystallite sizes, and compact density of the films, decreased when compared to CIS and (112) peak shifted to higher Bragg's angle, upon Al incorporation. The dislocation density and strain were found to increase with Al doping. Solar cells with SS/Mo/CIAS/CdS/iZnO: AZnO/Al configuration were fabricated and were tested for current-voltage characteristics for various `x' values, under Air Mass 1.5 Global one sun illumination. The best CIAS solar cell showed the efficiency of 6.8%, with x = 0.13, Eg = 1.17 eV, fill factor 45.04, and short circuit current density J(sc) 30 mA/cm(2).

Crystal structure of a tripeptide containing aminocyclododecane carboxylic acid: a supramolecular twisted parallel -sheet in crystals

The crystal structure of a tripeptide Boc-Leu-Val-Ac(12)c-OMe (1) is determined, which incorporates a bulky 1-aminocyclododecane-1-carboxylic acid (Ac(12)c) side chain. The peptide adopts a semi-extended backbone conformation for Leu and Val residues, while the backbone torsion angles of the C-,C--dialkylated residue Ac(12)c are in the helical region of the Ramachandran map. The molecular packing of 1 revealed a unique supramolecular twisted parallel -sheet coiling into a helical architecture in crystals, with the bulky hydrophobic Ac(12)c side chains projecting outward the helical column. This arrangement resembles the packing of peptide helices in crystal structures. Although short oligopeptides often assemble as parallel or anti-parallel -sheet in crystals, twisted or helical -sheet formation has been observed in a few examples of dipeptide crystal structures. Peptide 1 presents the first example of a tripeptide showing twisted -sheet assembly in crystals. Copyright (c) 2016 European Peptide Society and John Wiley & Sons, Ltd.

Growth mechanism of the interdiffusion zone between platinum modified bond coats and single crystal superalloys

Pt-modified beta-NiAl bond coats are applied over the superalloys for oxidation protection in jet engine applications. However, as shown in this study, it also enhances the growth of the interdiffusion zone developed between the bond coat and the superalloy along with brittle precipitates. Location of the Kirkendall plane indicates that a precipitate free sublayer grows from the bond coat, whereas another sublayer grows from the superalloy containing very high volume fraction of precipitates. With increasing Pt content, thickness of both the sublayers increases because of an increase in diffusion rates of the components. Quantitative electron probe microanalysis indicates high concentration of refractory components in the precipitates. Transmission electron microscopy shows that Rene N5 superalloy produces TCP phases mu and P, whereas CMSX-4 superalloy produces mu and sigma in the interdiffusion zone. With increasing Pt content in the bond coat, the average size of the precipitates decreases when coupled with Rene N5. Precipitates become much finer when the same bond coats are coupled with CMSX-4. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

CuIn1-xAlxSe2 Thin Films Grown by Co-Sputtering and Modified Selenization: Application in Flexible Solar Cells

Thin films of CuIn1-xAlxSe2 (CIAS) were grown on the flexible 10 micrometer thin stainless steel substrates, by dc co-sputtering from the elemental cathodes, followed by annealing with modified selenization. CuInAl alloyed precursor films were selenized both by noble gas assisted Se vapor transport in a tubular furnace and vacuum evaporation of Se in an evaporation chamber. CIAS thin films were optimized for better adhesion. X-ray diffraction, scanning electron microscopy, and UV-visible absorption spectroscopy were used to characterize the selenized films. The composition of CIAS films was varied by substituting In with Al in CuInSe2 (CIS) from 0 <= x <= 0.65 (x = Al/Al+In). Lattice parameters, average crystallite sizes, and compact density of the films, decreased when compared to CIS and (112) peak shifted to higher Bragg's angle, upon Al incorporation. The dislocation density and strain were found to increase with Al doping. Solar cells with SS/Mo/CIAS/CdS/iZnO: AZnO/Al configuration were fabricated and were tested for current-voltage characteristics for various `x' values, under Air Mass 1.5 Global one sun illumination. The best CIAS solar cell showed the efficiency of 6.8%, with x = 0.13, Eg = 1.17 eV, fill factor 45.04, and short circuit current density J(sc) 30 mA/cm(2).

Four- and five-component molecular solids: crystal engineering strategies based on structural inequivalence

A synthetic strategy is described for the co-crystallization of four-and five-component molecular crystals, based on the fact that if any particular chemical constituent of a lower cocrystal is found in two different structural environments, these differences may be exploited to increase the number of components in the solid. 2-Methylresorcinol and tetramethylpyrazine are basic template molecules that allow for further supramolecular homologation. Ten stoichiometric quaternary cocrystals and one quintinary cocrystal with some solid solution character are reported. Cocrystals that do not lend themselves to such homologation are termed synthetic dead ends.

Influence of Local Magnetic Fields on P-Doped Si Floating Zone Melting Crystal Growth in Microgravity

A two-dimensional axisymmetric numerical model is presented to study the influence of local magnetic fields on P-doped Si floating zone melting crystal growth in microgravity. The model is developed based on the finite difference method in a boundary-fitted curvilinear coordinate system. Extensive numerical simulations are carried out, and parameters studied include the curved growth interface shape and the magnetic field configurations. Computed results show that the local magnetic field is more effective in reducing the impurity concentration nonuniformity at the growth interface in comparison with the longitudinal magnetic field. Moreover, the curved growth interface causes more serious impurity concentration nonuniformity at the growth interface than the case with a planar growth interface.

DPIV and Interferometry Technique for Velocity Field and Concentration Fields Measurement in Crystal Growth

The property of crystal depends seriously on the solution concentration distribution near the growth surface of a crystal. However, the concentration distributions are affected by the diffusion and convection of the solution. In the present experiment, the two methods of optical measurement are used to obtained velocity field and concentration field of NaClO₃ solution. The convection patterns in sodium chlorate (NaClO₃) crystal growth are measured by Digital Particle image Velocimetry (DPIV) technology. The 2-dimentional velocity distributions in the solution of NaClO3 are obtained from experiments. And concentration field are obtained by a Mach-Zehnder interferometer with a phase shift servo system. Interference patterns were recorded directly by a computer via a CCD camera. The evolution of velocity field and concentration field from dissolution to crystallization are visualized clearly. The structures of velocity fields were compared with that of concentration field.

Effect of non-uniform magnetic field on crystal growth by floating-zone method in microgravity

The magnetic damping effect of the non-uniform magnetic field on the floating-zone crystal growth process in microgravity is studied by numerical simulation. The results show that the non-uniform magnetic field with designed configuration can effectively reduce the flow near the free surface and then in the melt zone. At the same time, the designed magnetic field can improve the impurity concentration non-uniformity along the solidification interface. The primary principles of the magnetic field configuration design are also discussed.