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A new sustainable concept for silicon recovery from diamond wire saw silicon powder waste: Source control and comprehensive conservation
No full textMetal impurities and SiO2 shell are two key components that must be eliminated for 6 N silicon remanufacturing from diamond wire saw silicon powder waste. Previous research on 6 N silicon recovery has focused more on metal impurity removal without paying sufficient attention to the relationship between metal impurities and the SiO2 shell, even though the surface oxidation of silicon particles is an important factor restricting metal removal. In this study, a novel investigation into the source of metal impurities and the SiO2 shell growth was conducted, combined with acid leaching and linear regression analysis to determine the relationship between the metal impurities and the SiO2 shell. The results indicated that both raw materials displayed strong negative correlations of -0.952 and -0.996 between the removal efficiency and the thickness of the SiO2 shell. And the Al, Fe, Ni, and Mg are more likely to be enriched in the SiO2 shell due to the improper management of metal contaminants and an increase in the O content in the waste stream. Furthermore, source control and comprehensive conservation are recommended for the efficient remanufacture of 6 N silicon. This study provides a new sustainable concept for silicon recovery from diamond wire saw silicon powder waste
Open Research Fund of State Key Laboratory of Multiphase Complex Systems of China[MPCS-2021-D-11]
No full textStudy on the possibility of diagonal line rule in elemental doping effects in Li4Ti5O12 by mechanochemical method
No full textLi4Ti5O12 (LTO) were doped with the same group element (Zr4+), diagonal elements (Nb5+ and W6+), and same period element (V5+) of titanium, respectively, to quantitative doping effect and explore the possibility of diagonal line rule in doping. It is conducive to synthesis doping Li4Ti5O12 with excellent properties by the ammonia-assisted mechanical ball-milling method (AAMBM). Through systematic experimental comparison, Li4Ti4.95Nb0.05O12 (LTNO) exhibits finer particle, higher specific surface area, narrower band gap, and more excellent electrochemical performance compared to others, since Nb and Ti have similar ion polarization ability, standard electrode potential, and the conjugable outer electron arrangement (Nb 4d45s1 whose 5 s electrons can be delocalized to d orbits to form half full orbit state). Particularly, LTNO shows the highest initial first discharged capability up to 151 mAh g(-1) and the capacity retention of 90% at 5 C rate after 300 cycles, indicating both outstanding high-rate discharge performance and cycling stability. The doping factor was proposed to roughly quantify their doping effect of Zr4+, Nb5+, V5+, and W6+, by using the ratio of specific capacity values of doped LTO and pure LTO after 500 cycles at 5 C, which are 1.2, 1.86, 1.05, and 1.08, respectively
Exploring dielectric spectra of polymer through molecular dynamics simulations
No full textIn this work, poly(N-isopropylacrylamide) (PNIPAM) was used as a research object to explore the feasibility of molecular dynamics (MD) simulations to study the dielectric properties of polymers. A comparison of the static dielectric constants for two different calculation schemes, the applied electric field method and the dipole moment fluctuation method, has been conducted. The dielectric properties of PNIPAM aqueous solutions with different concentrations were studied as a function of temperature. The static dielectric constants derived from dipole moment fluctuation method at different temperatures can accurately describe the phase transition process. The concentration does not affect the lower critical solution temperature, but significantly affects the relaxation process of the system. According to the frequency-dependent dielectric constants, two relaxation processes are observed, namely, the dielectric relaxation process in the region of frequency less than 30 terahertz (THz) determined by the synergistic interaction of PNIPAM and water molecules, and that in the region of frequency higher than 30 THz mainly determined by water molecules beyond the solvation shell of the polymer. The calculation results suggest that the dielectric behaviour is concentration and temperature independent, similar to Debye behaviour of bulk water. This method of calculating dielectric properties using MD simulations can be used in detecting the dynamic processes of soft condensed matter and in aiding the design of materials with excellent dielectric properties
Study on the synthesis and properties of novel grass green oxides based on Ba4In2-xMnxO7+y
No full textA new solid solution based on general formula Ba4In2-xMnxO7+y (0 < x < 0.2) has been successfully synthesized by the sol-gel method. The compounds exhibited grass green to olive colors. The origin of the color apparently due to the presence of Mn4+ as a chromophore in square pyramidal coordination. The X-ray diffraction results showed that the space group of all samples is I4/mmm. The oxidation state of Mn ion is confirmed to be +4 from the results of magnetization measurements and X-ray photoelectronic spectra (XPS). The color of Ba4In2O7 is white. With a small amount of Mn substitution, the color of Ba4In2-xMnxO7+y solid solution changes to grass green, and it turned to olive green when x = 0.2. The UV-Vis absorbance spectra revealed that the absorption peaks are fitted with d3 (Mn4+) configuration in the square pyramid, and the mechanism of color is explained
