The structural properties, heats of formation, elastic properties, and electronic structures of four compositions of binary A1-Li intermetallics, A13Li, A1Li, A12Li3, and A14Li9, are ana- lyzed in detail by using dens...The structural properties, heats of formation, elastic properties, and electronic structures of four compositions of binary A1-Li intermetallics, A13Li, A1Li, A12Li3, and A14Li9, are ana- lyzed in detail by using density functional theory. The calculated formation heats indicate a strong chemical interaction between A1 and Li for all the A1-Li intermetallics. In partic- ular, in the Li-rich A1-Li compounds, the thermodynamic stability of intermetallics linearly decreases with increasing concentration of.Li. According to the computational single crystal elastic constants, all the four A1-Li intermetallic compounds considered here are mechani- cally stable. The polycrystalline elastic modulus and Poisson＇s ratio have been deduced by using Voigt, Reuss, and Hill approximations, and the calculated ratios of bulk modulus to shear modulus indicate that the four compositions of binary A1-Li intermetallics are brittle materials. With the increase of Li concentration, the bulk modulus of A1-Li intermetallics decreases in a linear manner.展开更多
A room temperature ionic liquid crystal, 1-dodecyl-3-ethylimidazolium iodide （C12EImI）, and an ionic liquid, 1-decyl-3- ethylimidazolium iodide （Cl0EImI）, have been synthesized, characterized and employed as the e...A room temperature ionic liquid crystal, 1-dodecyl-3-ethylimidazolium iodide （C12EImI）, and an ionic liquid, 1-decyl-3- ethylimidazolium iodide （Cl0EImI）, have been synthesized, characterized and employed as the electrolyte for dye-sensitized solar cells （DSSC）. The physicochemical properties show that a smectic A （SmA） phase with a lamellar structure is formed in CIzEImI. Both C^2EImI and Cl0EImI have good electrochemical and thermal stability facilitating their use in DSSC. The steady-state voltammograms reveal that the diffusion coefficient of I3- in C^2EImI is larger than that in CmEImI, which is at- tributed to the existence of the SmA phase in Ca2EImI. Because the iodide species are located between the layers of imidazo- lium cations in CjzEImI, exchange reaction-based diffusion is increased with a consequent increase in, the overall diffusion. The electrochemical impedance spectrum reveals that charge recombination at the dyed TiOJelectrolyte interface of a C12EImI-based DSSC is reduced due to the increase in I3- diffusion, resulting in higher open-circuit voltage. Moreover, both short-circuit current density and fill factor of the Cl2EImI based DSSC increase, as a result of the increasing transport of I3 in C^2EImI. Consequently, the photoelectric conversion efficiency of C^2EImI-based DSSC is higher than that of the Cl0EImI-based DSSC.展开更多
文摘The structural properties, heats of formation, elastic properties, and electronic structures of four compositions of binary A1-Li intermetallics, A13Li, A1Li, A12Li3, and A14Li9, are ana- lyzed in detail by using density functional theory. The calculated formation heats indicate a strong chemical interaction between A1 and Li for all the A1-Li intermetallics. In partic- ular, in the Li-rich A1-Li compounds, the thermodynamic stability of intermetallics linearly decreases with increasing concentration of.Li. According to the computational single crystal elastic constants, all the four A1-Li intermetallic compounds considered here are mechani- cally stable. The polycrystalline elastic modulus and Poisson＇s ratio have been deduced by using Voigt, Reuss, and Hill approximations, and the calculated ratios of bulk modulus to shear modulus indicate that the four compositions of binary A1-Li intermetallics are brittle materials. With the increase of Li concentration, the bulk modulus of A1-Li intermetallics decreases in a linear manner.
基金supported by the National Basic Research Program of China(2011CBA00700)the National High Technology Research and Development Program of China(2011AA050510)the National Natural Science Foundation of China(21273242,21003130,21173227)
文摘A room temperature ionic liquid crystal, 1-dodecyl-3-ethylimidazolium iodide （C12EImI）, and an ionic liquid, 1-decyl-3- ethylimidazolium iodide （Cl0EImI）, have been synthesized, characterized and employed as the electrolyte for dye-sensitized solar cells （DSSC）. The physicochemical properties show that a smectic A （SmA） phase with a lamellar structure is formed in CIzEImI. Both C^2EImI and Cl0EImI have good electrochemical and thermal stability facilitating their use in DSSC. The steady-state voltammograms reveal that the diffusion coefficient of I3- in C^2EImI is larger than that in CmEImI, which is at- tributed to the existence of the SmA phase in Ca2EImI. Because the iodide species are located between the layers of imidazo- lium cations in CjzEImI, exchange reaction-based diffusion is increased with a consequent increase in, the overall diffusion. The electrochemical impedance spectrum reveals that charge recombination at the dyed TiOJelectrolyte interface of a C12EImI-based DSSC is reduced due to the increase in I3- diffusion, resulting in higher open-circuit voltage. Moreover, both short-circuit current density and fill factor of the Cl2EImI based DSSC increase, as a result of the increasing transport of I3 in C^2EImI. Consequently, the photoelectric conversion efficiency of C^2EImI-based DSSC is higher than that of the Cl0EImI-based DSSC.
