Densities and volumetric properties of 2-chloroethanol with N,N-dimethylformamide and water at different temperatures

Densities of binary mixtures of 2-chloroethanol with N,N-dimethylformamide (DMF) and water have been measured over the full range of compositions at various temperatures. From these results, excess molar volumes, V^E and excess partial molar volumes at infinite dilution, V¯_i^E,0 have been calculated. V^E for (DMF + 2-chloroethanol) mixture are positive over the whole mole fraction range and negative values are obtained for (water + 2-chloroethanol) mixture.     

Excess molar volumes of ternary mixtures {n-butylacetae + 1-butanol + 1, 2-butanediol} and {n-butylacetate + 1-butanol + 1, 3-butanediol} at T = 303.15 K

Excess molar volumes of the ternary systems formed by {n-butylacetate + 1-butanol + 1,2-butanediol } and {n-butylacetate + 1-butanol + 1,3-butanediol} were measured at 303.15 K for the whole composition range. The excess molar volumes, V_m^E, for binary mixtures of {n-butylacetate + 1-butanol, + 1,2-butanediol and + 1,3-butanediol} are positive and for the binary mixtures of {1-butanol + 1,2-butanediol and + 1,3-butanediol} are negative. Several empirical expressions are used to predict and correlate the ternary excess molar volumes from experimental results on the constituted binaries and analyzed to gain insight about liquid mixture interactions.     

Densities, excess molar volumes, and viscosities of the binary and ternary mixtures of {diethylcarbonate (1) + p-chloroacetophenone (2) + 1-hexanol (3)} at 303.15 K for the liquid region and at ambient pressure

Densities ρ, dynamic viscosities η, of the ternary mixture (diethylcarbonate + p-chloroacetophenone + 1-hexanol) and the involved binary mixtures (diethylcarbonate + p-chloroacetophenone), (diethylcarbonate + 1-hexanol), and (p-chloroacetophenone + 1-hexanol) have been measured over the whole composition range at 303.15 K for the liquid region and at ambient pressure. The data obtained are used to calculate excess molar volumes V_m^E, excess partial molar volumes V¯_m,i^E, limiting excess partial molar volumes V¯_m,i^E,∞, and viscosity deviations Δη, of the binary and ternary mixtures. The data of excess molar volumes of the binary systems were fitted to the Redlich–Kister equation while for the ternary system the Cibulka equation was used. The McAllister's four body, and Kalidas and Laddha interaction models are used to correlate the kinematic viscosities of binary and ternary mixtures, respectively, to determine the fitting parameters and the standard deviations. The experimental data of the constitute binaries and ternary are analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.     

Excess molar volumes,viscosity deviations,excess isentropic compressibilities and deviations in relative permittivities of (alkyl acetates (methyl,ethyl, butyl and isoamyl) + n-hexane, + benzene, + toluene, + (o-, m-, p-) xylenes, + (chloro-, bromo-, nitro-) benzene at temperatures from 298.15 to 313.15 K

The experimental densities (ρ), dynamic viscosities (η), speeds of sound (υ) and relative permittivities (ε_r) of thirty six binary mixtures of esters (methyl acetate, ethyl acetate, butyl acetate and isoamyl acetate) + organic solvents (n-hexane, benzene, toluene, o-, m-, p- xylenes), + halogenated benzene (chloro-, bromobenzene), + nitrobenzene have been measured over the complete composition range at atmospheric pressure and temperatures (298.15 to 313.15 K). The excess molar volumes, V_m^E, excess isentropic compressibilities, κ_s^E, deviations in relative permittivities, δε_r have been calculated and fitted to Redlisch–Kister type equation. The dynamic and kinematic viscosities have been correlated through Grunberg–Nissan and MacAllister equations. The qualitative analysis of various functions revealed that i.) esters lose their dipolar association in presence of inert and unlike n-hexane, ii.) specific but weaker n…π type interactions predominate in binary mixtures of esters + aromatic organic solvents and iii.) weak electron donor–acceptor complexes predominate in the mixtures of esters with halogenated and nitrated benzene.     

Thermophysical properties of binary mixtures (dimethyl carbonate + ketones) at T = (303.15, 308.15 and 313.15) K

The densities ρ, viscosities η, and refractive indices n_D of binary mixtures of dimethyl carbonate (DMC) with acetophenone, cyclopentanone, cyclohexanone, and 3-pentanone have been measured over the entire range of composition at the temperatures 303.15, 308.15 and 313.15 K and at atmospheric pressure. The density values were used to calculate excess molar volumes V^E, and other excess functions of interest such as deviations in viscosity Δη, excess Gibb's free energies of activation of viscous flow ΔG^E and deviations in molar refraction ΔR. The measured viscosities were compared with those predicted using the Grunberg-Nissan, Eyring-Margules, Soliman-Marshall, and McAllister four body models. Furthermore the refractive indices data have been correlated using Lorentz-Lorentz, Weiner, Newton, Gladstone-Dale, Eykman, and Eyring-John equations and a satisfactory agreement was found for all the binary systems studied in the present work.     

Viscosity and excess molar volume of binary mixtures of methanol with n-butylamine and di-n-butylamine at 303.15, 313.15 and 323.15 K. Characterization in terms of ERAS model

The excess molar volume V_m^E, viscosity deviation Δη, and excess Gibbs energy of activation ΔG^?E of viscous flow have been investigated from the density ρ and viscosity η measurements of binary mixtures of methanol with n-butylamine and di-n-butylamine over the entire range of mole fractions at 303.15, 313.15, and 323.15 K. The systems studied exhibit very strong cross association through strong O–H…N bonding between –OH and –NH– groups. As a consequence of this strong intermolecular association, both the systems have very large negative V_m^E and positive Δη and ΔG^?E over entire range of composition and at all the temperatures of investigation. V_m^E of the studied mixtures is consistently described by the ERAS model. The values of cross association constants K_AB illustrate that cross-associates are more pronounced in primary amine mixtures than that in secondary amine.     

Thermodynamic investigations of ternary o-toluidine + tetrahydropyran + N,N-dimethylformamide mixture and its binaries at 298.15, 303.15 and 308.15 K

The densities ρ, speed of sound u, data of o-toluidine (i) + tetrahydropyran (j) + N,N-dimethylformamide (k) and its {tetrahydropyran (j) + N,N-dimethylformamide (k); o-toluidine (i) + N,N-dimethylformamide (k)} binaries have been measured as a function of composition at 298.15, 303.15 and 308.15 K. The excess molar enthalpies, H^E data of same set of binary mixtures have also been measured over entire composition at 308.15 K. The densities and speeds of sound data of binary and ternary mixtures have been utilized to determine their excess molar volumes, V^E and excess isentropic compressibilities, κ_S^E. The observed thermodynamic properties of binary and ternary mixtures have been analyzed in terms of Graph theory. It has been observed that Graph theory correctly predicts the sign as well as magnitude of thermodynamic properties.     

On the rate constants of OH + HO2 and HO2 + HO2: A comprehensive study of H2O2 thermal decomposition using multi-species laser absorption

Hydrogen peroxide (H₂O₂) and hydroperoxy (HO₂) reactions present in the H₂O₂ thermal decomposition system are important in combustion kinetics. H₂O₂ thermal decomposition has been studied behind reflected shock waves using H₂O and OH diagnostics in previous studies (Hong et al. (2009) [9] and Hong et al. (2010) [6,8]) to determine the rate constants of two major reactions: H₂O₂ + M → 2OH + M (k₁) and OH + H₂O₂ → H₂O + HO₂ (k₂). With the addition of a third diagnostic for HO₂ at 227 nm, the H₂O₂ thermal decomposition system can be comprehensively characterized for the first time. Specifically, the rate constants of two remaining major reactions in the system, OH + HO₂ → H₂O + O₂ (k₃) and HO₂ + HO₂ → H₂O₂ + O₂ (k₄) can be determined with high-fidelity.No strong temperature dependency was found between 1072 and 1283 K for the rate constant of OH + HO₂ → H₂O + O₂, which can be expressed by the combination of two Arrhenius forms: k₃ = 7.0 × 10¹² exp(550/T) + 4.5 × 10¹⁴ exp(?5500/T) [cm³ mol^?1 s^?1]. The rate constants of reaction HO₂ + HO₂ → H₂O₂ + O₂ determined agree very well with those reported by Kappel et al. (2002) [5]; the recommendation therefore remains unchanged: k₄ = 1.0 × 10¹⁴ exp(?5556/T) + 1.9 × 10¹¹⁺exp(709/T) [cm³ mol^?1 s^?1]. All the tests were performed near 1.7 atm.     

Electronic core levels of hydroxyls at the surface of chromia related to their XPS O 1s signature: A DFT + U study

The Cr 2p and O 1s binding energy (BE) levels have been calculated by first principles methods for different models of hydroxylated (0001)-Cr₂O₃ surfaces. Several surface terminations have been considered. The calculations allow us to reproduce the O 1s shifts between O in oxide and OH groups. It is found that two main effects account for the OH binding energy shifts. On the one hand, the increased covalency of the O–H bond with respect to the Cr–O bond, lowers the electronic O (1s and 2p) energy, and in consequence the BE of the core levels (O 1s) are higher. On the other hand, the lower the OH coordination number, the higher the valence and core levels energy, and the lower the BE. Consequently, mono-coordinated hydroxyls have a binding energy near that of O^2? in the oxide (ΔBE_OH–O = ? 0.2–0.0 eV). Two-fold coordinated hydroxyls have a slightly higher BE (ΔBE_OH–O = + 0.3 eV). Three-fold coordinated OH groups have a higher binding energy (ΔBE_OH–O = + 0.6?0.7 eV), corresponding to that experimentally measured for OH groups. Finally, water adsorbed above OH groups exhibits a still higher BE (ΔBE_HOH–O = + 0.9–1.0 eV). The ΔBE are slightly under-estimated under the initial state approximation, and overestimated under the final state (Z + 1) approximation.     

Improved electrical parameters of vacuum annealed Ni/4H-SiC (0 0 0 1) Schottky barrier diode

The reported work has been focused on the improvement of electrical parameters of Schottky diode using vacuum annealing at mild temperature in Ar gas ambient. Nickel Schottky barrier diodes were fabricated on 50 μm epitaxial layer of n-type 4H-SiC (0 0 0 1) substrate. The values of leakage current, Schottky barrier height (?_B), ideality factor (η) and density of interface states (N_SS) were obtained from experimentally measured current–voltage (I–V) and capacitance–voltage (C–V) characteristics before and after vacuum annealing treatment. The data revealed that ?_B, η and reverse leakage current for the as-processed diodes are 1.25 eV, 1.6 and 1.2 nA (at ?100 V), respectively, while for vacuum annealed diodes these parameters are 1.36 eV, 1.3 and 900 pA (at same reverse voltage). Improved characteristics have been resulted under the influence of vacuum annealing because of lesser number of minority carrier generation due to incessant reduction of number of available discrete energy levels in the bandgap of 4H-SiC substrate and lesser number of interface states density at Ni/4H-SiC (0 0 0 1) interface.     

Metastable helium atom scattering from Ni(1 1 0) surface

The survival probability (SP) of metastable helium atoms (He¹) during scattering from the clean, alkalated and oxygen-adsorbed Ni(1 1 0) surfaces has been examined in the kinetic energy range of 50–400 meV. The measurements were carried out using a time-of-flight technique and a pulsed-discharge type metastable helium atom source. The SP is nearly constant for a kinetic energy (E_kin) of 50–100 meV and decreases exponentially with the increase in E_kin at 100–400 meV. It has been shown that the SP at E_kin=100–400 meV depends on the repulsive part of the He¹-surface interaction potential.     

High resolution emission spectroscopy of the E2Π–X2Σ+ transition of SrH and SrD

Emission spectra of SrH and SrD have been studied at high resolution using a Fourier transform spectrometer. The molecules have been produced in a high temperature furnace from the reaction of strontium metal vapor with H₂/D₂ in the presence of a slow flow of Ar gas. The spectra observed in the 18 000–19 500 cm^?1 region consist of the 0–0 and 1–1 bands of the E²Π–X²Σ⁺ transition of the two isotopologues. A rotational analysis of these bands has been obtained by combining the present measurements with previously available pure rotation and vibration–rotation measurements for the ground state, and improved spectroscopic constants have been obtained for the E²Π state. The present analysis provides spectroscopic constants for the E²Π state as ΔG(½) = 1166.1011(15) cm^?1, B_e = 3.805503(32) cm^?1, α_e = 0.098880(47) cm^?1, r_e = 2.1083727(89) Å for SrH, and ΔG(½) = 839.1283(23) cm^?1, B_e = 1.918564(15) cm^?1, α_e = 0.034719(23) cm^?1, r_e = 2.1121943(83) Å for SrD.     

Crystal growth and structural properties of the spinel-type Li1 + xMn2 − xO4 (x = 0.10, 0.14)

Single crystals of the lithium-rich lithium manganese oxide spinels Li_1 + xMn_2 − xO₄ with x = 0.10 and 0.14 have been successfully synthesized in high-temperature molten chlorides at 1023 K. The single-crystal X-ray diffraction study confirmed the cubic Fd3¯m space group and the lattice parameters of a = 8.2401(9) Å for x = 0.10 and a = 8.2273(10) Å for x = 0.14 at 300 K, respectively. The crystal structures have been refined to the conventional values R = 3.7% for x = 0.10 and R = 3.1% for x = 0.14, respectively. Low-temperature single-crystal X-ray diffraction experiments revealed that these single crystal samples showed no phase transition between 100 and 300 K. The electron-density distribution images in these compounds by the single-crystal MEM analysis clearly showed strong covalent bonding features between the Mn and O atoms due to the Mn–3d and O–2p interaction.     

Modelling the directional and energy dependence of 5–10 keV Ar+ ion-induced secondary electron yields from Cu crystals

The primary ion directional effects observed in secondary electron yields induced by ion bombardment [5 keV Ar⁺ → Cu(100)] are simulated using a semi-empirical molecular dynamics model. The directional effects are presumed to arise from inelastic energy transfers that take place in close binary atomic encounters. The latter are estimated using the Oen-Robinson model, in combination with a critical apsidal distance (R_c). The connection between the measured kinetic electron emission (KEE) yields (γ_KEE) and the predicted inelastic energy loss in a binary atomic collision (ΔE_i) is established through a semi-empirical fitting procedure involving R_c and other parameters in the following model: γ_e = γ₀ + γ_KEE = γ₀ + 〈ΔE_i(z)exp(? z/λ)〉, where z is the collision depth. The directional effects are best reproduced by fitting the model to Ar–Cu inelastic collisions for two azimuthal incident directions: R_c is estimated to be 0.47 ± 0.03 Å; the parameter, λ (an effective electron attenuation length), is estimated to be 18 ± 2 Å. The same model also describes the γ_KEE energy dependence for 5–10 keV Ar⁺ normally incident on low-index Cu crystal targets [Phys. Rev. 129 (1963) 2409]. The spatial and temporal distributions of the hard collisions that initiate KEE are discussed on the basis of the model.     

Fragmentation of 370 MeV/n 20Ne and 470 MeV/n 24Mg in light targets

Total charge-changing cross sections and cross sections for the production of projectile-like fragments were determined for fragmentation reactions induced by 370 MeV/n ²⁰Ne ions in water and lucite, and 490 MeV/n ²⁴Mg ions in polyethylene, carbon and aluminum targets sandwiched with CR-39 plastic nuclear track detectors. An automated microscope system and a track-to-track matching algorithm were used to count and recognize the primary and secondary particles. The measured cross sections were then compared with published cross sections and predictions of different models. Two models and the three-dimensional Monte Carlo Particle Heavy Ion Transport Code System (PHITS) were used to calculate total charge-changing cross sections. Both models agreed within a few percent for the system ²⁴Mg + CH₂, however a deviation up to 20% was observed for the systems ²⁰Ne + H₂O and C₅H₈O₂, when using one of the models. For all the studied systems, PHITS systematically underestimated the total charge-changing cross section. It was also found that the partial fragmentation cross sections for ²⁴Mg + CH₂ measured in present and earlier works deviated up to 20% for Z = 6–11. Measured cross sections for the production of fragments (Z = 4–9) for ²⁰Ne + H₂O and C₅H₈O₂ were compared with predictions of three different semi-empirical models and JQMD which is used in the PHITS code. The calculated cross sections differed from the measured data by 10–90% depending on which fragment and charge was studied, and which model was used.     

Band overlap via chemical pressure control in double perovskite (Sr2−xCax)FeMoO6 (0 ⩽ x ⩽ 2.0) with TMR effect

The chemical pressure control in (Sr_2−xCa_x)FeMoO₆ (0 ⩽ x ⩽ 2.0) with double perovskite structure has been investigated systematically. We have performed first-principles total energy and electronic structure calculations for x = 0 and x = 2.0. The increasing Ca content in (Sr_2−xCa_x)FeMoO₆ samples increases the magnetic moment close to the theoretical value due to reduction of Fe/Mo anti-site disorder. An increasing Ca content results in increasing (Fe²⁺ + Mo⁶⁺)/(Fe³⁺ + Mo⁵⁺) band overlap rather than bandwidth changes. This is explained from simple ionic size arguments and is supported by X-ray absorption near edge structure (XANES) spectra and band structure calculations.     

Reaction of tert-butyl isocyanate and tert-butyl isothiocyanate at the Ge(100) − 2 × 1 Surface

The adsorption of tert-butyl isothiocyanate and tert-butyl isocyanate at the Ge(100) ? 2 × 1 surface was probed using multiple internal reflection Fourier transform infrared (FTIR) spectroscopy X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) modeling. Results indicate that there are multiple surface products for each molecule. FTIR studies of tert-butyl isothiocyanate reveal adsorption through an S-dative bonded state, while XPS studies further suggest a reactive desorption product which leaves excess sulfur atoms at the surface. Studies of tert-butyl isocyanate indicate that the molecule dissociatively adsorbs at the surface, resulting in tert-butyl and germyl isocyanate groups, as the major pathway, in addition to forming several minor products, including a [2 + 2] cycloaddition product across the C=N bond. DFT was used to simulate vibrational spectra and map the reaction pathways, and confirms that the assigned products are energetically favorable.     

Synthesis,characterization and photovoltaic properties of novel molecules based on triarylamine dyes

We report the synthesis, electrochemical and photovoltaic properties of triphenylamine based novel organic sensitizer, comprising donor, electron-conducting and anchoring group. Different triphenylamines were synthesized as donor unit and connected to cyano-acidic acid acceptor over vinyl group. In this work, we studied on two novel dyes (TPA2, TPA3) by attaching methyl to m-position and diphenylamine to p-position of the basic triphenylamine structure, respectively. All derivatives absorb at visible region of solar spectrum in the range of 350–632 nm. By introducing strong electron injection groups to triphenylamine ring, band gap becomes narrower while E_HOMO–E_LUMO levels are tuned. All current voltage (I–V) measurements were done under 100 mW/cm² light intensity and AM 1.5 conditions. TPA3 chromophore with the lowest band gap shows the best cell performance with an efficiency (η) of 4.12%, a short-circuit photocurrent density (I_sc) of 8.07 mA/cm², an open-circuit voltage (V_oc) of 714 mV and a fill factor (FF) of 0.72.     

Influence of rapid thermal annealing on electrical and structural properties of double metal structure Au/Ni/n-InP (1 1 1) diodes

The effect of rapid thermal annealing on the electrical and structural properties of Ni/Au Schottky contacts on n-InP have been investigated by current–voltage (I–V), capacitance–voltage (C–V), auger electron spectroscopy (AES) and X-ray diffraction (XRD) techniques. The Au/Ni/n-InP Schottky contacts are rapid thermally annealed in the temperature range of 200–500 °C for a duration of 1 min. The Schottky barrier height of as-deposited Ni/Au Schottky contact has been found to be 0.50 eV (I–V) and 0.86 eV (C–V), respectively. It has been found that the Schottky barrier height decreased with increasing annealing temperature as compared to as-deposited sample. The barrier height values obtained are 0.43 eV (I–V), 0.72 eV (C–V) for the samples annealed at 200 °C, 0.45 eV (I–V) and 0.73 eV (C–V) for those at 400 °C. Further increase in annealing temperature to 500 °C the barrier height slightly increased to 0.46 eV (I–V) and 0.78 eV (C–V) compared to the values obtained for the samples annealed at 200 °C and 400 °C. AES and XRD studies showed the formation of indium phases at the Ni/Au and InP interface and may be the reason for the increase in barrier height. The AFM results showed that there is no significant degradation in the surface morphology (rms roughness of 1.56 nm) of the contact even after annealing at 500 °C.     

Excess molar volumes, viscosities, and refractive indices for binary and ternary mixtures of {cyclohexanone (1) + N,N-dimethylacetamide (2) + N,N-diethylethanolamine (3)} at (298.15, 308.15, and 318.15) K

Densities ρ, viscosities η, and refractive indices n_D, of the binary and ternary mixtures formed by cyclohexanone + N,N-dimethylacetamide + N,N-diethylethanolamine were measured at (298.15, 308.15, and 318.15) K for the liquid region and at ambient pressure for the whole composition ranges. The excess molar volumes V_m^E, viscosity deviations Δη, and refractive index deviations Δn_D, were calculated from experimental densities and refractive indices. The excess molar volumes are positive over the mole fraction range for binary mixtures of cyclohexanone(1) + N,N-dimethylacetamide (2) and N,N-dimethylactamide (2) + N,N-diethylethanolamine (3) and increase with increasing temperatures from (298.15 to 318.15) K. The excess molar volumes of cyclohexanone (1) + N,N-diethylethanolamine (3) are S-shaped dependence on composition with negative values in the N,N-diethylethanolamine rich-region and positive values at the opposite extreme and increase with increasing temperatures from (298.15 to 318.15) K. The excess molar volumes are positive over the whole mole fraction ranges for the ternary mixtures at all temperatures. Viscosity deviations are negative over the mole fraction range for all binary and ternary mixtures and decrease with increasing temperatures from (298.15 to 318.15) K. Refractive index deviations are negative over the mole fraction range for all binary and ternary mixtures and increase with increasing temperatures from (298.15 to 318.15) K. The experimental data of constitute were correlated as a function of the mole fraction by using the Redlich–Kister equation for binary and , Cibulka, Jasinski and Malanowski , Singe et al., Pintos et al., Calvo et al., Kohler, and Jacob–Fitzner for ternary mixture, respectively. McAllister^'s three body, Hind, and Nissan–Grunberg models were used for correlating the kinematic and dynamic viscosity of binary mixtures. The experimental data of the constitute binaries are analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.