Abstract: The objective of this paper is to show that annealing lithiated transition metal oxide
(LTMO) precursors obtained by the sol-gel method at insufficiently high temperatures may not produce the intended pure cathode active materials required in lithium batteries. In this work, LiMn1.5Ni0.5O4 which is a potential cathode active material in the 5 V-class is prepared by the solgel method. The precursor material was obtained when the solid gel was dried and heated at different temperatures in the range between 200 °C and 900 °C for 4 hours. It was observed that on
heating the precursor material at least at 500 °C for 4 hours the material produced was LiMn1.5Ni0.5O4 in the present form as proven by the x-ray diffractogram (XRD). On heating at temperatures below this, the formation of LiMn1.5Ni0.5O4 was uncomplete and at temperatures above 500 °C the intensity of the peak at 2q = 18° decreases. The noise level also increased at temperatures above 500 °C.
Abstract: Nonempirical study of the site preference occupation for Ni and V substituting in Fe3Al has been carried out in the framework of the coherent potential approximation. Obtained values of total energies show in a full agreement with experiments that Ni atoms in the equilibrium configuration occupy the iron sub-lattice for alloying with 5 at % of Ni in the Fe3Al-based alloy.
Calculations of alloys with the V-doped iron aluminide in the D03 phase show differences in bonding and site occupation preferences in comparison with Ni doping. V atoms occupy aluminum sublattice.
Abstract: Zeta potential (ZP) of poly-tetrafluoroethylen (PTFE) and polyamide 6 (PA 6) foils was measured using the streaming potential method. All measurements were carried out in a flat cell where PTFE foils are usually used in electrokinetic measurements as a part of the measuring device, to form the channel and to achieve a proper distance between the foils surface of measured samples.
The primary interest of the present work was to investigate the influence of pretreatment of PTFE foils on their electrokinetic properties in order to find out to what extent such pretreatment may affect measuring results of other samples and to develop a procedure of PTFE foils preparation with purpose to achieve the same initial conditions for all measurements.
Abstract: Films of chitosan polymer doped with lithium acetate dihydrate (LiOAc.2H2O) and
placticized with oleic acid (OA) and palmitic acid (PA) were prepared by the solution cast technique. The film containing 40.0 wt. % LiOAc and 10.0 wt. % of OA exhibit a room temperature conductivity of ~ 10-5 S cm-1 and the film containing 41.0 wt. % LiOAc and 7.7 wt. % of PA has conductivity ~ 10-6 S cm-1. The plot of ln(sT) versus 103/T for the highest conducting samples obey an Arrhenian relationship in the temperature range between 300 and 363 K implying that the
conductivity is thermally assisted. FTIR spectroscopy and XRD techniques have been used for the complexation studies. The LiNiCoO2/chitosan-LiOAc-OA/MCMB electrochemical cell could be charged to a voltage of 4.2 V.
Abstract: Although LiMn2O4 is a very promising material for use as cathodes in lithium ion batteries, it exhibits capacity fading on cycling. Substituting some of the Mn with a 3d metal may improve the stability of the material. In this research, LiMn(2-x)CuxO4 (where x = 0.2 and 0.4) are synthesized and characterized by TGA, XRD and EDX. Cyclic voltammetry is also done to study their electrochemical characteristics. Results indicate improved thermal stability and some structural
change in the material. Cyclic voltammetry results show the redox potentials have been shifted from those obtained from pure LiMn2O4 material.
Abstract: Authors have successfully synthesized a new environmental catalysis which reacted with harmful formaldehyde in air at room temperature. Although manganese oxide is practically used for a major ingredient of formaldehyde removing materials, intermediates such as formate formed on the surface reduced the removal efficiency. Then, manganese oxide was photodeposited onto the surface of titanium dioxide particles which could decompose certain organic compounds with UV
irradiation. It was confirmed that the complex oxide decomposed formaldehyde into carbon dioxide at room temperature. Moreover, UV irradiation enhanced the production of the carbon dioxide.
Abstract: Polyethylene terephthalate (PET) is one of the major electret materials which has been studied and widely used in charge storage applications for a long time. The homo-charge and hetero-charge formation responsible for the electret effect of PET can be explained by the dipolar polarization, space charge separation and charge injection respectively as a result of contact poling or corona charging. These processes are also verifiable from studies of surface charges and thermally
stimulated depolarization current (TSDC) of the PET films. Now consider a stack of PET films charged under the same condition as a single film. It would be intuitively expected that the electret effects of the individual films of the stack should be different due to their different positions in the stack. However, in a recent study on charged PET stacks, it was found that the electret effects of the individual films are quite similar. The surface charges of the individual films are about the same and
they sum to make same total as a single charged PET film. On the other hand, the TSDC thermograms of individual films show similar characteristics in the thermal relaxation processes where homo- and hetero- charge effects are still observed. From the TSDC results, especially for the film in the middle of a triple layer sandwich, it shows clearly dipolar polarization and charge injection related peaks. These findings agree with the results of surface charge studies of the
Abstract: Nanometre-sized structures were fabricated by electron beam-induced deposition in a scanning transmission electron microscope. A small amount of metal-organic gases, W(CO)6 and dimethyl acetylacetonato gold, were introduced near a substrate in the chamber of the microscope. The gas was decomposed by the irradiation of focused electron beams and nanometre-sized deposits containing W or Au were produced. Moving the beam position enables us to produce structures with a variety of shapes. High-resolution electron microscopy observation revealed that the structures consisted of nano-crystalline and amorphous parts.
Abstract: A collection of AlSi7 closed cell foams were fabricated following the powder
metallurgical route [1,2], reaching densities between 540 Kg/m3 and 1350 Kg/m3. Thermal conductivity of the samples was determined using the Transient Plane Source technique (TPS) [3,4], and influence of density was estimated. Several models were tested, and the correlation between experimental data and theoretical results was evaluated. Finally, measurements in different directions were performed, revealing the use of the TPS technique as a non-destructive tool to investigate the existence of in-homogeneities derived from the foaming process.
Abstract: A new metal-assisted chemical etching method using Na2S2O8 as an oxidant is proposed to form a porous layer on a multicrystalline silicon (mc-Si). This method does not need an external bias and enables formation of uniform porous silicon layers, more rapidly than the conventional stain etching method. A thin layer of Pd is deposited on the mc-Si surface prior to immersion in a solution of HF and Na2S2O8. The characterisations of etched layer formed by this method as a function of etching time were investigated by scanning electron microscopy, X-ray diffraction (XRD), Energy-dispersive X-ray (EDX) and reflectance spectroscopy. It shows that the surface is porous and the etching is independent of grain orientation. In addition, reflectance measurements made with a variety of etching conditions show a lowering of the reflectance from 25 % to 6 % measured with respect to the bare as-cut substrate. However, this result can be improved by changing the experimental conditions (concentration, time, temperature, …).