| 1. |
- Sugiyama, Jun, et al.
(författare)
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How Li diffusion in spinel Li[Ni1/2Mn3/2]O4 is seen with μ ±SR
- 2021
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Ingår i: Zeitschrift fur physikalische Chemie (Munchen. 1991). - : Walter de Gruyter GmbH. - 0942-9352 .- 2196-7156.
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Tidskriftsartikel (refereegranskat)abstract
- The diffusive behavior in a spinel-type Li+ ion battery material, Li[Ni1/2Mn3/2]O4, has been studied with positive and negative muon spin rotation and relaxation (μ±SR) measurements in the temperature range between 200 and 400 K using a powder sample. The implanted μ+ locates at an interstitial site near O2- ion so as to form a O-H like bond, while the implanted μ- is mainly captured by an oxygen nucleus, resulting in the formation of muonic oxygen. This means that local magnetic environments in Li[Ni1/2Mn3/2]O4 were investigated from the two different sites in the lattice, i.e., one is an interstitial site for μ+SR and the other is an oxygen site for μ-SR. Since both μ+SR and μ-SR detected an increase in the fluctuation rate of a nuclear magnetic field for temperatures above 200 K, the origin of this increase is clearly confirmed as Li diffusion. Assuming a random walk process with the hopping of thermally activated Li+ between a regular Li site and the nearest neighboring vacant octahedral sites, a self-diffusion coefficient of Li+ was found to range above 10-11 cm2/s at temperatures above 250 K with an activation energy of about 0.06 eV.
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| 2. |
- Iqbal, Z., et al.
(författare)
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Photocatalytic degradation of dyes in aqueous media by gum shellac stabilized selenium nanoparticles
- 2023
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Ingår i: Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics. - 0942-9352. ; 237:8, s. 1139-1152
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Tidskriftsartikel (refereegranskat)abstract
- The present work outlines the successful synthesis of selenium nanoparticles (Se NPs) stabilized with gum shellac (GS) and their use as photocatalyst for the enhanced degradation of dyes. Se NPs were synthesized by a simple and cost effective chemical reduction method using selenious acid, GS and sodium borohydride. Gum shellac was used as stabilizing agent. The orange red gum shellac-selenium nanoparticles (GS-Se NPs) were characterized by UV-Vis spectroscopy, Fourier transform infra-red (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The morphology of these particles appeared to be uniform and spherical as observed in SEM images. Energy dispersive X-ray spectroscopic profile showed the presence of elemental selenium, carbon and oxygen. The synthesized GS-Se NPs were investigated for their photo-catalytic efficiency towards degradation of methylene blue (MB) and methyl orange (MO) dye in aqueous media. Absorbance was measured at ?(max) 665 nm and 455 nm for MB and MO, respectively. Maximum degradation of MB in-comparison with MO obtained at 50 mg/L were 81.72 % and 71.42 % respectively. A very slow degradation rate was observed for the MO and MB in the absence of synthesized photocatalyst whereas greater percentage degradation was observed for the GS-Se NPs.
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