Pure Solid State Research Articles

A study of binary iron/lithium organometallic complexes as single source precursors to solid state cathode materials for potential Li ion battery application

Solid state and solution phase decomposition of organometallic half sandwich and sandwich complexes of type [CpFeCODLi × DME] 1, [CpFeCODLi × TMEDA] 2 and [(Cp) 2FeLi 2 × 2 TMEDA] 3 (Cp = cyclopentadienyl, COD = 1,5-cyclooctadiene, DME = dimethoxyethane, TMEDA = tetramethylethylenediamine) derived from ferrocene, yield different kinds of lithium ferrites under oxidative and inert conditions. Thermogravimetry (TG) and TG coupled mass spectrometry of these compounds indicate that the decomposition begins above 170 °C for 1, 185 °C for 2 and 190 °C for 3 with removal of all the organic ligands. In the absence of oxygen, compounds 1, 2 and 3 decompose to a mixture of Fe, Fe 3C and Li 2O/Li 2CO 3 at temperatures above 200 °C. Amorphous α-LiFeO 2 is formed in the temperature range of 200–400 °C in the presence of oxygen. Crystalline α-LiFeO 2 is formed only above 400 °C using 1. Elemental analysis of the LiFeO 2 obtained from 1 indicates a drastic decrease in the carbon and hydrogen content with the increase in the oxidation temperature. XRD reveals the presence of Li 2CO 3 as second phase formed for precursors 1, 2, and 3 under oxidative conditions. Solution phase decomposition of 2 and 3 in the absence of oxygen followed by annealing at 600 °C yields Li 2Fe 3O 5, Li 5FeO 4 and Fe 3C depending on the solvent to precursor ratio in contrast to the α-LiFeO 2 phase formed under pure solid state decomposition conditions. However, all lithium ferrites (Li 2Fe 3O 5, Li 5FeO 4) are converted to α-LiFeO 2 when oxidized above 500 °C. The α-LiFeO 2 products were further characterized by IR, XPS, and TEM. Electrochemical analysis of the α-LiFeO 2 was performed, showing a moderate initial capacity of 13 mAh/g.

Solid-state photochromism of pyrazolones with highly improved sensitivity, fatigue resistance and reversible fluorescent switching properties

Photochromic compounds derived from pyrazolones, which undergo reversible photoisomerization reactions in pure solid state, were synthesized toward the end of designing novel solid-state photonic switches. The materials exhibit high sensitivity, excellent fatigue resistance and reversible fluorescent switching properties with distinguishable contrast signals under alternating UV irradiation and heating. The mechanism of the photochromic reactions was verified by FT-IR and XPS. The detailed analysis of the spectra and crystal structure of the materials revealed that their photochromism resulted from tautomerization between their enol and keto forms accompanied by proton transfer.

Organic crystals: More than simple additives toward better electroceramic materials

Roles of various organic crystals (OC), notably those containing nitrogen, on the preparation and properties of source materials for electroceramics are featured from the author's own experimental studies. When OC are intimately mixed with metal salts like carbonates, their decomposition is accelerated, liberating the diffusing species at temperatures lower than usual. Mixing of OC with metal oxides under mechanical stressing results in anion exchange and eases diffusion of guest species. Case studies on 3 categories, i.e. i) substitution of oxygen in titania with nitrogen and introduction of oxygen vacancies during co-grinding titania with urea, glycine and/or polytetra fluoroethylene; ii) increase in the rate of reaction of barium titanate formation via a solid state route by OCs with detailed process analysis with glycine as an example of OC, and iii) phase pure solid state synthesis of Li4Ti5O12 by mechanically activating the intermediate, Li2TiO3 with 3 amino acids as OCs.

Pure chiral organic thin films with high isotropic optical activity synthesized by UV pulsed laser deposition

We show that the pulsed laser deposition (PLD) technique allows us to elaborate pure molecular solid state thin films based on binaphthyl molecules featuring high isotropic optical rotation (HIOR). The transfer of chirality from the ablated target to the substrate was probed by polarimetry and circular dichroism (CD) measurements. A rotary power of 12° mm at 546 nm has been obtained. CD spectroscopy confirms both the chiral and the isotropical nature of the deposited thin films and put into evidence the disorder between the naphthyl chromophores inside the molecular material. Finally, we highlight three regimes for the deposition mechanism depending on the laser fluence: desorption without racemisation, desorption with racemisation, and ablation with degradation. These results demonstrate that, by properly adjusting the growth conditions, isotropic purely organic chiral films can be grown by PLD, thereby opening the prospect for the synthesis of high value organic materials for applications such as waveguiding.

Thermal characterization of new complexes of Zn(II) and Cd(II) with some bipyridine isomers and propionates

Abstract New mixed ligand complexes of the following stoichiometric formulae: M(2-bpy)2(RCOO)2·nH2O, M(4-bpy)(RCOO)2·H2O and M(2,4’-bpy)2(RCOO)2·H2O (where M(II)=Zn, Cd; 2-bpy=2,2’-bipyridine, 4-bpy=4,4′-bipyridine, 2,4′-bpy=2,4′-bipyridine; R=C2H5; n=2 or 4) were prepared in pure solid-state. These complexes were characterized by chemical and elemental analysis, IR and conductivity studies. Thermal behaviour of compounds was studied by means of DTA, DTG, TG techniques under static conditions in air. The final products of pyrolysis of Cd(II) and Zn(II) compounds were metal oxides MO. A coupled TG/MS system was used to analyse of principal volatile products of thermal decomposition or fragmentation of Zn(4-bpy)(RCOO)2·H2O under dynamic air and argon atmosphere. The principal species correspond to: C+, CH+, CH3 +, C2H2 +, HCN+, C2H5 + or CHO+, CH2O+ or NO+, CO2 +, 13C16O2 + and 12C16O18O+ and others; additionally CO+ in argon atmosphere.

Confinement of chiral molecules in reverse micelles: FT-IR, polarimetric and VCD investigation on the state of dimethyl tartrate in sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles dispersed in carbon tetrachloride

The state of d and l-dimethyl tartrate confined within dry sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles dispersed in CCl 4 has been investigated by FT-IR spectroscopy, polarimetry, and vibrational circular dichroism (VCD). Measurements have been performed at 25 °C as a function of the solubilizate-to-surfactant molar ratio ( R) at a fixed AOT concentration (0.158 M). The analysis of experimental data is consistent with the hypothesis that both enantiomers of dimethyl tartrate are mainly entrapped in the reverse micelles and located in proximity to the surfactant head-group region. The formation of this interesting self-organized chiral nanostructure involves some changes of the typical H-bonding of dimethyl tartrates in the pure solid state or as monomers dispersed in CCl 4 attributable to the establishment of specific solubilizate/surfactant head-group interactions and confinement effects.

Synthesis and characterization of new metal(II) complexes with formates and some nitrogen donor ligands

New mixed-ligands complexes with empirical formulae: M(2,4′-bpy)2L2·H2O (M(II)Zn, Cd), Zn(2-bpy)3L2·4H2O, Cd(2-bpy)2L2·3H2O, M(phen)L2·2H2O (where M(II)=Mn, Ni, Zn, Cd; 2,4′-bpy=2,4′-bipyridine, 2-bpy=2,2′-bipyridine, phen=1,10-phenanthroline, L=HCOO−) were prepared in pure solid state. They were characterized by chemical, thermal and X-ray powder diffraction analysis, IR spectroscopy, molar conductance in MeOH, DMF and DMSO. Examinations of OCO− absorption bands suggest versatile coordination behaviour of obtained complexes. The 2,4′-bpy acts as monodentate ligand; 2-bpy and phen as chelating ligands. Thermal studies were performed in static air atmosphere. When the temperature raised the dehydration processes started. The final decomposition products, namely MO (Ni, Zn, Cd) and Mn3O4, were identified by X-ray diffraction.

Solid state self-assembly of nanocheckerboards

The authors introduce an emergent method to fabricate a few-nanometer-size columnar superlattice with a checkerboard pattern in inorganic spinels by harnessing the Jahn-Teller structural distortion. Transmission electron microscope images reveal that the fundamental building blocks are two types of long nanorods with the ∼4×4×70nm3 size, which are alternatively stacked in a way that the cross sectional and side views show checkerboard and herringbone patterns, respectively. The authors discuss that the strain induced by the Jahn-Teller distortion causes this peculiar self-assembled nanostructure in the coherent mixture of two spinel phases. This pure solid state self-assembly can be implemented to fabricate heterogeneous nanostructures with practical functionalities.

Gibbs free energies for dual langmuir‐like adsorption onto hard carbon materials in sediment and soils

Adsorption of organic compounds onto hard carbon constituents of soils and sediments may be described by a dual Langmuir-like equation for adsorption onto high-energy sites and low-energy sites. To describe quantitatively the sorbate-sorbent interactions on these high-energy sites and low-energy sites, Gibbs free energies for adsorption onto several soils and sediments were calculated using suitable experimental sorption data from the literature. A large part of the variation in these Gibbs free energies relative to the pure solid state appeared to be related to differences in sorbate molecular symmetry. Generally, for a broad range of nonpolar organic compounds, from substituted benzenes to five-ring polycyclic aromatic hydrocarbons and hexachlorinated biphenyls, sorbate molecular symmetry-corrected Gibbs free energies for high-energy and low-energy adsorption relative to the pure solid state were within a narrow range or approximately -23 and -11 kJ/mol, respectively. These two average values for the geosorbents were comparable to corresponding values for adsorption onto activated carbon.

Kinetics of adsorption and desorption of some organochlorine compounds on black carbon in a sediment

Rate constants for adsorption and desorption of four organochlorine compounds on black carbon in a sediment were determined from measurements of the rate of removal, by gas purge, of the organochlorine compounds as single solutes from a water-sediment mixture immediately after addition of the solute to the system. The rates of removal fitted to a kinetic scheme based on Langmuir adsorption onto two types of sites in black carbon. The first-order rate constants for desorption from these sites were comparable to those for slow and very slow desorption from sediment. The time needed to reach apparent equilibrium in the experimental setup, with 10 g sediment/L water, ranged from 13 to 166 h, depending on the sorbate and the adsorption process. These short times to equilibrium suggest no need to assume rate-limiting diffusion from and to adsorption sites in this sediment. Average Gibbs free energies for adsorption of the four organochlorine compounds from the pure solid state were -10 +/- 3 and -20 +/- 3 kJ/mol for low-energy and high-energy sites, respectively, pointing to two different adsorption mechanisms.

New complexes of Mn(II), Co(II), Ni(II) AND Cu(II) with 2,2’- OR 2,4’-bipyridine and formates (Synthesis, thermal and other properties)

New mixed-ligand complexes with empirical formulae: Mn(2-bpy)1.5L2·2H2O, M(2-bpy)2L2·3H2O (M(II)=Co, Cu), Ni(2-bpy)3L2·4H2O and M(2,4’-bpy)2L2·2H2O (where 2-bpy=2,2’-bipyridine, 2,4’-bpy=2,4’-bipyridine; L=HCOO– ) have been obtained in pure solid-state. The complexes were characterized by chemical and elemental analysis, IR and VIS spectroscopy, conductivity (in methanol and dimethylsulfoxide). The way of metal-ligand coordination discussed. The formate and 2,4’-bpy act as monodentate ligands and 2-bpy as chelate ligand. The new complexes with ligand isomerism were identified. During heating the complexes lose water molecules in one or two steps. Thermal decomposition after dehydration is multistage and yields corresponding metal oxides as final products. A coupled TG-MS system was used to analysis principal volatile thermal decomposition (or fragmentation) products of Ni(2,4’-bpy)2(HCOO)2·2H2O under dynamic air or argon atmosphere.

Thermodynamics of solid silicon equilibrated with Si–Al–Cu liquid alloys

For discussing the addition of copper to the Si–Al solvents in the LPE growth of silicon and that in the solidification refining of silicon, the solubilities of aluminum at 1173, 1273, and 1373 K and copper at 1273 and 1373 K in solid silicon in equilibrium with liquid Si–Al–Cu alloys were investigated. Solubilities of aluminum and copper were determined by employing the temperature gradient zone melting method and diffusion experiment, respectively. The activity coefficient of copper in solid silicon at infinite dilution relative to the pure solid state was determined as follows R T ln γ Cu ( s ) in solid Si 0 = 166 , 000 ( ± 3500 ) − 47.6 ( ± 2.8 ) T ( J / mol ) ( 975 – 1602 K ) Copper additions to the Si–Al solvents decreased aluminum solubilities in solid silicon effectively and the contents of copper introduced into solid silicon were found to be fairly small.

Fugacity ratio estimations for high-melting rigid aromatic compounds

Prediction of the environmental fate of organic compounds requires knowledge of their tendency to stay in the gas and water phase. Vapor pressure and aqueous solubility are commonly used descriptors for these processes. Depending on the type of distribution process, values for either the pure solid state or the (subcooled) liquid state have to be used. Values for the (subcooled) liquid state can be calculated from those for the solid state, and vice versa, using the fugacity ratio. Fugacity ratios are usually calculated from the entropy of fusion and the melting point. For polycyclic aromatic hydrocarbons, chlorobenzenes, chlorodibenzofuranes, and chlorodibenzo( p)dioxins, fugacity ratios calculated using experimental entropies of fusion were systematically less than those obtained from a thermodynamically more rigorous approach using heat capacity data. The deviation was more than 1 order of magnitude at the highest melting point. The use of a universal value for the entropy of fusion of 56 J/mol K resulted in either over or underestimation by up to more than 1 order of magnitude. A simple correction factor, based on the melting point only, was derived. This correction factor allowed the fugacity ratios to be estimated from experimental entropies of fusion and melting point with an accuracy better than 0.1–0.2 log units.

Formation of TiBwreinforcement in in-situ titanium matrix composites

Formation of TiB_wreinforcement in in-situ titanium matrix composites

Solid Solubilities and Thermodynamic Properties of Aluminum in Solid Silicon

The solid solubilities of aluminum in silicon in the temperature range of 1016–1622 K have been measured by introducing aluminum into solid silicon by passing a molten silicon-aluminum zone through single crystalline silicon with temperature gradient zone melting method. The maximum solubility was found to be in molar fraction around 1450 K. The activity coefficient of aluminum in solid silicon at infinite dilution relative to the pure solid state was determined as (J/mol) (1016-1622 K). © 2003 The Electrochemical Society. All rights reserved.

Electron beam processed transdermal delivery system for administration of an anti-anginal agent

Electron beam irradiation was used to synthesize a matrix type transdermal system of isosorbide dinitrate, an effective anti-anginal agent. The drug was dissolved in two monomeric systems, 2-ethylhexyl acrylate (EHA) and 2-ethylhexyl acrylate : methyl methacrylate (9 : 1). The solutions were then directly irradiated on a backing membrane (Scotchpak ®1006) at different doses to get transdermal patches. The developed systems were evaluated for residual monomer content, equilibrium weight swelling ratio, weight uniformity, thickness uniformity, drug content, peel strength, in vitro release and skin permeation kinetics. They possessed excellent tack and adhesive properties. In the case of isosorbide dinitrate–EHA systems, an increase in the peel strength values with respect to the skin was observed with increasing radiation doses. The systems exhibited promising skin permeation kinetics favorable for transdermal drug delivery. The radiation stability of the drug in the pure solid state form was also assessed.

Superconducting properties of Bi 2− xPb xSr 2Ca 2Cu 3O y system derived via sol–gel and solid state routes

Bulk Pb doped Bi 2− x Pb x Sr 2Ca 2Cu 3O y ( x = 0.4 and 0.5) superconductors have been prepared via sol–gel route (SGR) using pure metal acetate precursors and solid state route (SSR) using conventional carbonate-oxide compounds. Variation of the percentage of high- T C phase (2223-phase) for samples prepared by different routes were observed from XRD data and it was found that SGR samples have higher percentage of (2223) phase than the SSR samples. It was ∼75% and ∼78% for SSR samples and ∼85% and ∼95% in SGR samples for doping composition of x = 0.4 and x = 0.5, respectively. The highest zero bulk resistance temperature ( T C( R = 0)) of 104 K was found in SGR sample ( x = 0.5), while the lowest T C( R = 0) value of 98 K was measured in SSR sample ( x = 0.4). Complex ac susceptibility measurements showed that the nature of the grains, grain boundaries and coupling associated to the superconducting properties were superior in SGR samples, hence sol–gel route appears to be a more suitable method in the preparation of single-phase BSCCO superconductor.

Thermodynamics of Ti in Cu–Ti alloy investigated by the EMF method

Abstract The thermodynamics of Ti in Cu–Ti alloy at 1423 K was determined by means of an oxygen sensor employing ZrO 2 (2.14wt%MgO) as the solid electrolyte. Ti 2 O was the equilibrium phase in the interfacial reaction layer formed by the reaction of Ti with Al 2 O 3 . Activities of titanium and copper relative to pure solid state were investigated, and both Cu and Ti in the system showed negative deviation from Raoult’s law. The increment of Ti concentration increased the activity coefficient of Ti and reduced the activity coefficient of copper. The activity coefficient of titanium in infinite dilution copper, γ Ti 0 , self-interaction coefficient e Ti Ti , and the standard Gibbs free energy of solution of Ti in copper relative to 1wt% Ti, Δ G 0 (Ti in Cu melt) at 1423 K were measured in the present study being γ Ti 0 = 0.200, e Ti Ti =4.828 and Δ G 0 (Ti in Cu melt) =−70.179 kJ/mol respectively. The thermodynamic functions of mixing and excess were determined at 1423 K, respectively, Δ G Cu−Ti X =Δ H Cu−Ti M =−19.17 X Ti +33.07 X Ti 2 (kJ/mol) ( X Ti ≤0.0325), and Δ G Cu−Ti M =−0.093−78.67 X Ti +344.9 X Ti 2 (kJ/mol) (X Ti ≤0.0325). The limiting partial enthalpy of solution of supercooled liquid Ti in copper at 1373 K was found to be −11.97 kJ/mol according to regular solution method.

SULFUR-CENTERED RADICALS IN UV-IRRADIATED PHOSPHORODITHIOATES

Some bis(dialkoxythiophosphoryl) disulfides and bis(dialkyl phosphorodithioato) ammonium and potassium salts have been irradiated in pure solid state by mercury high pressure lamp at 77 K. Depending on the sample methyl and sulfur-centered radicals are produced. The sulfur radicals are identifed as thio radicals [(RO)2P(S)S.].

Oriented Self-Assembly of Cyclic Peptide Nanotubes in Lipid Membranes

Polarized attenuated total reflectance (ATR), grazing angle reflection−absorption, and transmission Fourier transform infrared (FT-IR) spectroscopy methods have been used to investigate the orientation of peptide nanotubes in the functionally relevant environment of ordered phospholipid multibilayers. Eight-residue cyclic peptides of alternating d- and l-amino acids which self-assemble to form open-ended, tubular structures have been shown previously to function as transmembrane channels for ion transport. Although the tubular structure of the peptide assembly has been established in the pure solid state, this study presents the first detailed biophysical investigation of the peptide nanotubes within the context of the lipid film to afford a quantitative estimate of their angle of orientation relative to the lipid bilayer. We find by ATR IR that in accordance with the previous structure−function model hypothesis for a transport-competent channel, the central axis of nanotubes composed of cyclo[(l-Trp-d-Le...