Simultaneous WDXS and EBSD investigations of dense PLZT ceramics

Electron probe microanalysis (EPMA) with appropriate standards and precisely adjusted experimental conditions has been successfully applied to an accurate quantitative elemental analysis of the lead–lanthanum–zirconium–titanate (PLZT) ceramics with composition Pb_1-3x/2La_xZr_0.65Ti_0.35O₃, where x = 0.08. Heterogeneity tests for Pb, La, Ti and Zr performed on highly dense polycrystalline PLZT ceramics showed relatively large scatter in some data, especially for Ti. To check whether the crystallographic orientations or misorientations of PLZT grains have any potential influence on the chemical composition determined by the wavelength-dispersive X-ray spectroscopy (WDXS), orientation maps have been measured, for exactly same areas as in the WDXS measurements. The measurements of single orientations in the PLZT grains were performed with the use of an electron backscatter diffraction (EBSD) facility attached to a low-vacuum scanning electron microscope (LV-SEM). The single orientation maps of the PLZT samples and corresponding WDXS semi-quantitative results for cations concentration distribution are presented and discussed.     

Preparation of nanocrystalline palladium on p-Si by electroless deposition and its photo-electrochemical hydrogen evolution property

1. Introduction Because of the fast development of the modern industry in the last century, the reserves of fossil en-ergy resources, such as oil, natural gas, and coal, were reduced rapidly. In addition, the contamination of global environment aggravated because of the industrial growth. To overcome these problems and to find a source of renewable energy, scientists have extensively studied the utilization of hydrogen en-ergy for several decades, which is harmless to the environment [1]. Fuji…     

Silicon/graphite composites as an anode material for lithium ion batteries

Mixed silicon–graphite composites have been prepared by means of mechanical milling process. Their micro-heterogeneous structure is considered responsible for electrode failures. A fingerprint of this process is seen by cycling the carbonaceous component of the composite in an electrolyte containing small amount of propylene–carbonate (PC). Local voltage drops close to 0 V (versus Li metal) resulted in local electrode mechanical deterioration. In the presence of silicon particles such local disorders would lead to a loose interparticle contact (zones called dead spots). Deterioration pattern of the mixed composite electrode may be considered as a set of ‘dead spots’ spreading across the electrode as the cycling proceeds. Hence, a careful optimization is necessary in order to fabricate composite electrode giving minimum local disorders and having satisfactory cycling performance.     

Advanced lanthanide doped upconversion nanomaterials for lasing emission

Microlasers are narrow-band and coherent light from small cavities, which have been widely applied in biomedicine, optical interconnection, integration devices, etc. Lanthanide doped upconversion materials are potential gain media for microlasers from near infrared (NIR) to visible and UV regimes due to their multi ladder-like metastable energy levels and superior optical frequency conversion capability. The optical feedback from photon scattering of the porous upconversion nanoparticles clusters has been reported to produce upconversion random lasers. The light bouncing back and forth between two reflective surfaces or internal surface has been utilized to achieve modulated upconversion lasing emission. In addition, photon lattices and plasmonic cavities with enhanced electromagnetic fields can amplify the upconversion process within the sub-diffraction volumes and produce highly efficient upconverting lasers. In this review, the recent advances on using lanthanide doped upconversion materials for random, whispering gallery mode (WGM)/Fabry-Perot (FP) cavity and photon lattice/plasmonic cavity modulated upconversion microlasers are overviewed. Current challenges and future directions of the upconverting lasers are also discussed.     

In situ synthesis and ammoxidation activity of ammonium salt of molybdophosphoric acid on VOPO4 catalysts

Two isomorphous VOPO₄ catalysts were prepared and used as support materials for the in situ synthesis of ammonium salt of 12-molybdophosphoric acid (AMPA) from their solid phase phosphate component. Formation of AMPA was confirmed by the XRD and FTIR analyses. The activity of the catalysts in the ammoxidation reaction revealed that the in situ synthesized AMPA catalysts are more active than the parent VOPO₄ catalysts in the conversion of 2-methylpyrazine to 2-cyanopyrazine.     

Flow insensitive points-to sets

Pointer analysis is an important part of source code analysis. Many programs that manipulate source code take points-to sets as part of their input. Points-to related data collected from 27 mid-sized C programs (ranging in size from 1168 to 87,579 lines of code) is presented. The data shows the relative sizes and the complexities of computing points-to sets. Such data is useful in improving algorithms for the computation of points-to sets as well as algorithms that make use of this information in other operations.     

Hydrogen uptake of manganese oxide-multiwalled carbon nanotube composites

Hydrogen uptake of pristine multi-walled carbon nanotubes is increased more than three-fold at 298 K and hydrogen pressure of 4.0 MPa, upon addition of hydrogen spillover catalyst manganese oxide, from 0.26 to 0.94 wt%. Simple and convenient in situ reduction method is used to prepare Mn-oxide/MWCNTs composite. XRD, FESEM, and TEM demonstrates nanostructural characterization of pristine MWCNTs and composite. TGA analysis of Mn-oxide/MWCNTs composites showed a single monotonous fall related to MWCNTs gasification. Enhancement of hydrogen storage capacity of composite is attributed to spillover mechanism owing to decoration of Mn-oxide nanoparticles on outer surface of MWCNTs. Hydrogen uptake follows monotonous dependence on hydrogen pressure. Oxide-MWCNTs composite not only shows high hydrogen storage capacity as compared to pristine, but also exhibit significant cyclic stability upon successive adsorption–desorption cycles.     

Enhanced photocatalytic H2 evolution and phenol degradation over sulfur doped meso/macroporous g-C3N4 spheres with continuous channels

S-doped meso/macroporous g-C₃N₄ spheres (SMCN) were successfully synthesized via an in situ novel method utilizing millimeter-scale porous silica spheres as template and thiourea as precursor and S source. Such SMCN possessed millimeter-scale spherical morphology with continuous channels at 20–80 nm in the interior of the spheres, and exhibited increased H₂ generation rate (15 times) and phenol degradation rate (5 times) under visible light irradiation compared with that over pristine g-C₃N₄, mainly due to the enlarged surface area, enhanced mass transfer and improved efficiency of charges separation all stemming from the synergetic effects of the S doping and pore creating. Notably, density functional theory (DFT) calculations were employed to further understand the mechanism of the photocatalytic enhancement with regard to the optical absorption property at atomic level. Combined with the finite difference time domain (FDTD) simulations aiming at evaluating the effect of the nanoscale pore architecture on the optical absorption ability, it was revealed that not only the S doping but also the meso/macroporous structure resulted in the enhancement of the optical absorption, which was considered to be an essential role for the enhanced photocatalytic performances over SMCN.