| 1. |
- Shen, Qiuwan, et al.
(author)
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Effect of A/B-site substitution on oxygen production performance of strontium cobalt based perovskites for CO2 capture application
- 2015
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In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 5:50, s. 39785-39790
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Journal article (peer-reviewed)abstract
- Oxy-fuel combustion is one of the proposed technologies which have the potential to achieve zero CO2 emission. Strontium cobalt based perovskite oxygen carriers are promising materials for air separation with a high selectively for oxygen. And these perovskites can produce an oxygen enriched carbon dioxide stream for an oxy-fuel combustion process. The relatively low oxygen production yield may be a drawback of this type of material for this technology. This paper presents an effective approach by A/B-site substitution to improve the oxygen production performance of the perovskites. In this study, a series of different A/B-site substituted SrCo0.8Fe0.2O3-delta were prepared by an EDTA-citrate sol-gel combustion synthesis method. Fixed-bed experiments and TGA measurements were performed to study the effects of A/B-site substitution on cyclic oxygen adsorption/desorption performance of the synthesized samples. The experimental results indicate that the oxygen desorption amounts of different A-site substituted perovskites decrease in the order of BaCo0.8Fe0.2O3-delta > Ba0.5Sr0.5Co0.8Fe0.2O3-delta > SrCo0.8Fe0.2O3-delta > Sr0.5Ca0.5Co0.8Fe0.2O3-delta > MgCo0.8Fe0.2O3-delta. Moreover, B-site substitution by different transition metal ions can significantly modify oxygen adsorption capacity and oxygen desorption performance of SrCo0.8Fe0.2O3-delta. Furthermore, oxygen desorption performance can be improved when Fe ions of the perovskite SrCo0.8Fe0.2O3-delta are substituted by Zr, Cr, Zn, and Ni ions.
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| 2. |
- Luo, Ning, et al.
(author)
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Band-inverted gaps in InAs/GaSb and GaSb/InAs core-shell nanowires
- 2016
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Journal article (peer-reviewed)abstract
- The [111]-oriented InAs/GaSb and GaSb/InAs core-shell nanowires have been studied by the 8 × 8 Luttinger-Kohn "Equation missing" Hamiltonian to search for non-vanishing fundamental gaps between inverted electron and hole bands. We focus on the variations of the band-inverted fundamental gap, the hybridization gap, and the effective gap with the core radius and shell thickness of the nanowires. The evolutions of all the energy gaps with the structural parameters are shown to be dominantly governed by the effect of quantum confinement. With a fixed core radius, a band-inverted fundamental gap exists only at intermediate shell thicknesses. The maximum band-inverted gap found is ~4.4 meV for GaSb/InAs and ~3.5 meV for InAs/GaSb core-shell nanowires, and for the GaSb/InAs core-shell nanowires the gap persists over a wider range of geometrical parameters. The intrinsic reason for these differences between the two types of nanowires is that in the shell the electron-like states of InAs is more delocalized than the hole-like state of GaSb, while in the core the hole-like state of GaSb is more delocalized than the electron-like state of InAs, and both favor a stronger electron-hole hybridization.
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