Search results for "Lithium"
showing 10 items of 680 documents
Novel Functionality of Lithium-Impregnated Titania as Nanocatalyst
2019
The present work incorporates the synthesis of a multifunctional catalyst for the transesterification of waste cooking oil (WCO) to biodiesel and recovery of rare earth elements (REEs). For this purpose, TiO2 nanoparticles and TiO2 doped with lithium ions were prepared. The influence of lithium ions on the catalytic performance of TiO2 was attained by impregnation of the different molar ratios of lithium hydroxide to bare TiO2. Then each catalyst was screened for catalytic conversion of WCO to fatty acid methyl ester (FAME) and also for REEs recovery. All synthesized materials were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Transmission electron microsc…
Nanotechnology in lithium niobate for integrated optic frequency conversion in the UV
2017
In the domain of Earth Explorer satellites nanoengineered nonlinear crystals can optimize UV tunable solid-state laser converters. Lightweight sources can be based on Lithium Niobate (LN) domain engineering by electric field poling and guided wave interactions. In this Communication we report the preliminary experimental results and the very first demonstration of UltraViolet second-harmonic generation by first-order quasi-phase-matching in a surface-periodically-poled proton-exchanged LN waveguide. The pump source was a Ti-Sapphire laser with a tunability range of 700- 980 nm and a 40 GHz linewidth. We have measured UV continuous-wave light at 390 nm by means of a lock-in amplifier and of …
Optical properties and structure particularities of LiNbO 3 crystals grown from a boron-doped melt
2019
A series of LiNbO3:B crystals was grown from the melt doped by boron. It is shown that LiNbO3:B crystals possess an increased resistance to optical damage. We have found changes according to Raman spectra confirming the ordering of Li+, Nb5+ cations and vacancies along the polar axis. The chemical interactions were studied in the system Li2O–B2O3–Nb2O5. Boron cations are unable to incorporate into a cation sublattice of LiNbO3, but they change the physic-chemical structure of a melt. It contributes to an increased structure and optical uniformity of LiNbO3:B.
Stable proton exchanged waveguides in Lithium Tantalate
2008
alpha, beta(1), and kappa(2) phases are investigated for planar waveguide fabrication by proton exchange in congruent lithium tantalate. The effective indices of planar waveguide eigenmodes were monitored over time, revealing that the exchange process induces aging instabilities in all phases except alpha.
Effect of doping and crystallite size on the electrochemical performance of Li4Ti5O12
2016
Abstract Defect spinel phase lithium titanate (Li 4 Ti 5 O 12 ) has been suggested as a promising negative electrode material for next generation lithium ion batteries. Flame spray pyrolysis has been shown to be a viable fast, one-step process for synthesis of nanoparticulate Li 4 Ti 5 O 12 . However, due to the rapid quenching that is integral to the process the crystallite size remain very small and non-uniform. To overcome this shortcoming a vertical flow tube furnace was used to increase the high-temperature residence time. This resulted in an increase in the crystallite size and crystallinity of the product. As a result of this increase the electrochemical performance of the Li 4 Ti 5 …
The European contribution to the development and validation activities for the design of IFMIF lithium facility
2013
The International Fusion Materials Irradiation Facility (IFMIF) is an accelerator-driven intense neutron source where candidate materials for fusion reactors will be tested and validated. The high energy neutron flux is produced by means of two deuteron beams (total current of 250 mA, energy of 40 MeV) that strikes a liquid lithium target circulating in a lithium loop of IFMIF plant. The European (EU) contribution to the development of the lithium facility comprises five procurement packages, as follow: (1) participation to the experimental activities of the EVEDA lithium test loop in Oarai (Japan); (2) study aimed at evaluating the corrosion and erosion phenomena, promoted by lithium, for …
A Review of using spray pyrolysis through Sol-gel materials in the synthesis of cathode materials for lithium-ion batteries
2016
Over the years, new synthesis routes of the cathode electrochemical active material for lithium-ion batteries have improved remarkably to optimize their capacity and cycle life performance. This review study focused on the use of some techniques to synthesize the common cathode materials (LiCoO2, LiMn2O4, LiFePO4). The most common and simplest synthesis method was the mixing of powders in their solid-state form and heating them at relatively high temperatures over long periods. Other methods included the formation of sol-gel products that could be either heat-treated more or could be used directly by means of a spray pyrolysis method producing the desired active material. The spray pyrolysi…
Substituted 1,4-Diaza-1,3-butadiene Monocyclopentadienyl Titanium Complexes. Crystal Structure of Ti(η5-C5Me5)(η4-iPrNCHCHNiPr)Me
2000
We report the synthesis of 1,4-diaza-1,3-butadiene (dad) complexes Ti(η5-C5R5)(η4-R‘2-dad)Cl (R = H, Me; R‘ = iPr, tBu) by reaction of Ti(η5-C5R5)Cl3 (R = H, Me) with the dilithium salts of diisopropyl- and di-tert-butyl-substituted 1,4-diaza-1,3-butadienes (Li2[R‘2-dad]). Alkylation of the pentamethylcyclopentadienyl diisopropyl and di-tert-butyl derivatives with methylmagnesium chloride and methyllithium gave complexes Ti(η5-C5Me5)(η4-iPr2-dad)Me and Ti(η5-C5Me5)(η4-tBu2-dad)Me, respectively. Addition of excess water to di-tert-butyl chloro complexes gave the oxo-bridged complexes [{Ti(η5-C5R5)(η4-tBu2-dad)}2(μ-O)] (R = H, Me). The temperature-dependent spectroscopic behavior of Ti(η5-C5H…
Performance of Thin-Film Lithium Energy Cells under Uniaxial Pressure
2008
The objective of this study was two-fold. The first objective was to determine if the all-solid-state thin-film lithium energy cells could withstand the minimal 550 kPa uniaxial pressure required for composite manufacturing, which both specimens successfully did. The second objective was to determine the upper boundary uniaxial pressure limit of operation for the all-solid-state thin-film lithium energy cells. The two all-solid- state thin-film lithium energy cells tested in the present study under uniaxial pressure performed well even when subjected to uniaxial pressures up to about 2.0 MPa. However, pressures higher than this value led to their degradation. The observed degradation was du…
Coordination polymers based on diiron tetrakis(dithiolato) bridged by alkali metals, electrical bistability around room temperature, and strong antif…
2015
Coordination polymer chains have been formed by the direct reaction between HSC6H2Cl2SH and FeCl3·6H2O in the presence of an aqueous solution of the corresponding alkali-metal hydroxide (M = Li, Na, and K) or carbonate (M = Rb and Cs). The structures consist of dimeric [Fe2(SC6H2Cl2S)4](2-) entities bridged by [M2(THF)4] [M = K (1), Rb (2), and Cs (3); THF = tetrahydrofuran] or {[Na2(μ-H2O)2(THF)2] (5 and 5') units. The smaller size of the lithium atom yields an anion/cation ion-pair molecule, [Li(THF)4]2[Fe2(SC6H2Cl2S)4] (4), in which the dianionic moieties are held together by Cl···Cl interactions. Electrical characterization of these compounds shows a general semiconductor behavior in wh…