Search

In this work we report our First-Principles simulations results of the electrolyte properties of Li18P6N16. The obtained simulations of the idealized electrolyte properties suggest that this material is promising solid electrolyte for usage in Li-Ion batteries having Li anode. The simulated crystal structure of this material is found to be in good agreement with experimental data. The phase transition of LiPN2 and Li7PN4 to Li18P6N16 at high pressure has been validated through the simulations and found to be in consistent with experiment. The simulations of idealized interfaces with metallic Li anode demonstrate that studied material is likely to form a metastable interface with Li metal. The Li - ion migration analysis suggests that the Li ion migration is dominated with the vacancy migration mechanism which takes place along the c - axis only in Li18P6N16. The calculated value of the Li - ion migration activation energy was found to be in good agreement with experiment suggesting that this material possess a promising Li ion conductivity. [ABSTRACT FROM AUTHOR]

We study the internal structure of nanometer-sized D2O-nonane aerosol droplets formed in supersonic nozzle expansions using a variety of experimental techniques including small angle X-ray scattering (SAXS). By fitting the SAXS spectra to a wide range of droplet structure models, we find that the experimental results are inconsistent with mixed droplets that form aqueous core-organic shell structures, but are quite consistent with spherically asymmetric lens-on-sphere structures. The structure that agrees best with the SAXS data and Fourier transform infra-red spectroscopy measurements is that of a nonane lens on a sphere of D2O with a contact angle in the range of 40°-120°. [ABSTRACT FROM AUTHOR]

Two recently synthesized crystalline materials which belong to the LiPON materials family, Li12P3N9 and it’s high–pressure polymorph Li4PN3, have been computationally examined as solid electrolytes for the usage in Li–ion batteries through first–principles simulations. The simulations of the idealized electrolyte properties of both materials suggests that these materials are promising solid electrolytes. The simulated crystal structures of both materials found to be in good agreement with experimental data, the phase transition between Li12P3N9 and Li4PN3 at high pressure has been validated through the simulations and found to be consistent with computational and experimental literature. The Li–ion migration analysis predicts that these materials are a very promising conductors for Li–ions with a calculated value for the activation energy comparable and even smaller to those of good solid electrolytes in the same materials family. The Li–ion migration analysis also suggests that the Li–ion migration is dominated with the vacancy migration mechanism which takes place along the three diffusion axes in Li12P3N4 and along the c–axis only in Li4PN3. The simulations of idealized interfaces with metallic Li anode demonstrate that these materials are likely to form a metastable interfaces with Li metal. [ABSTRACT FROM AUTHOR]

The original formula of Gibbs for the reversible work of critical nucleus formation is evaluated in three approximate ways for ordinary and heavy water. The least approximate way employs an equation of state to evaluate the pressure difference between the new and old phases. This form of the theory yields a temperature dependence for the nucleation rate close to that observed experimentally. This is a substantial improvement over the most commonly used (and most approximate) form of classical theory.© 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The Monte Carlo simulation has been used to investigate the magnetic properties of a mixed spin-1 (sublattice A) and spin-1/2 (sublattice B), where each sublattice has a rectangular structure and the whole lattice system forms a 2-D centered rectangular lattice. Five possible interactions are considered. Namely, two S–S interactions and two $\sigma $ – $\sigma $ interactions depend on crystal direction, and an antiferromagnetic interaction between the two sublattices is taken. Our results show that the critical temperature increases with increasing the variation of any exchange interactions. The existence of the compensation temperature depends on the balance between the S–S interactions along and $\sigma $ – $\sigma $ interactions along [01] directions. [ABSTRACT FROM AUTHOR]

Thermodynamic, dynamical, and structural properties of ethanol are numerically studied using two ethanol models: TraPPE-UA and OPLS-AA. These properties are computed with temperatures ranging from 200K to 300K, with steps of 10K, and also with different mole fractions of ethanol at 300K. The TraPPE-UA and OPLS-AA models are mixed with two water models: SPCE and TIP4P. These models have been previously shown to be the best models of methanol among nine different models. In our previous paper on methanol-water mixtures, the OPLS-AA model showed superiority over the TraPPE-UA model in predicting most properties. In this study, we show that the TraPPE-UA has better predictions in all computed properties when compared to the experimental results, except for the total structure factor of mixing with respect to the second maximum. [ABSTRACT FROM AUTHOR]

Two intermolecular potential models of methanol (TraPPE-UA and OPLS-AA) have been used in order to examine their validity in reproducing the selected structural, dynamical, and thermodynamic properties in the unary and binary systems. These two models are combined with two water models (SPC/E and TIP4P). The temperature dependence of density, surface tension, diffusion and structural properties for the unary system has been computed over specific range of temperatures (200-300K). The very good performance of the TraPPE-UA potential model in predicting surface tension, diffusion, structure, and density of the unary system led us to examine its accuracy and performance in its aqueous solution. In the binary system the same properties were examined, using different mole fractions of methanol. The TraPPE-UA model combined with TIP4P-water shows a very good agreement with the experimental results for density and surface tension properties; whereas the OPLS-AA combined with SPCE-water shows a very agreement with experimental results regarding the diffusion coefficients. Two different approaches have been used in calculating the diffusion coefficient in the mixture, namely the Einstein equation (EE) and Green-Kubo (GK) method. Our results show the advantageous of applying GK over EE in reproducing the experimental results and in saving computer time. [ABSTRACT FROM AUTHOR]

Intrinsically conducting polyaniline is grafted onto a preformed poly(styrene-co-maleanilic acid) copolymer backbone via chemical oxidative coupling of aniline in acidified chloroform/water emulsion. The structure and textural morphology of the grafted poly(S-co-MA-g-PANI) are examined by different spectroscopic, thermal, powder X-ray diffraction and scanning electron microscopic techniques. The d.c. electrical conductivity of the grafted emeraldine base of the obtained materials displays a d.c. conductivity of the order of 10-7 - 10-9 Scm-1, which is ∼2 orders of magnitude greater than that of the reported PANI-EB homopolymer. This enhancement in d.c. conductivity is explained in terms of microstructure-electronic conductivity relationship. [ABSTRACT FROM AUTHOR]