Structure-Property Correlations and Superconductivity in Spinels

In this chapter, alternative views based on the structure have been presented in the spinel superconducting compounds, including the only oxide spinel superconductor, LiTi2O4, and non-oxide superconductors, CuIr2S4 and CuV2S4. Inspection of the atomic arrangements, electronic structures and bonding interactions of spinel superconductor, LiTi2O4 shows that LiTi2O4 can be interpreted as Li-doped TiO2, which is similar with doping Cu into TiSe2 to induce superconductivity. Different from LiTi2O4, the electronic structures of CuIr2S4 and CuV2S4 indicate a distinctive way to understand them in the structural viewpoint. The d6 electron configuration and the octahedral coordination of Ir in CuIr2S4 can be analogous to the d6 in perovskites, which sometimes host a metal-insulator transition. However, the superconductivity in CuV2S4 may be induced from the suppression of charge density waves. This kind of structural views will help chemists understand physical phenomena obviously more straightforward, though not sufficient, as clearly shown by the competition between each other, such as superconductivity and other structural phase transition (CDWs), oxidation fluctuation or magnsetism

Development of novel CO2-stable oxygen permeable dual phase membranes for CO2 capture in an oxy-fuel process

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A CO2-stable reduction-tolerant Nd-containing dual phase membrane for oxyfuel CO2 capture

We report a novel CO2-stable reduction-tolerant dual-phase oxygen transport membrane 40 wt% Nd0.6Sr0.4FeO3-delta-60 wt% Ce0.9Nd0.1O2-delta (40NSFO-60CNO), which was successfully developed by a facile one-pot EDTA-citric sol-gel method. The microstructure of the crystalline 40NSFO-60CNO phase was investigated by combined in situ X-ray diffraction (XRD), scanning electron microscopy (SEM), back scattered SEM (BSEM), and energy dispersive X-ray spectroscopy (EDXS) analyses. Oxygen permeation and long-time stability under CO2 and CH4 atmospheres were investigated. A stable oxygen flux of 0.21 cm(3) min(-1) cm(-2) at 950 degrees C with undiluted CO2 as sweep gas is found which is increased to 0.48 cm(3) min(-1) cm(-2) if the air side is coated with a porous La0.6Sr0.4CoO3-delta (LSC) layer. All the experimental results demonstrate that the 40NSFO-60CNO not only shows good reversibility of the oxygen permeation fluxes upon temperature cycling, but also good phase stability in a CO2 atmosphere and under the harsh conditions of partial oxidation of methane to synthesis gas up to 950 degrees C.Sino-German Centre for Science Promotion/GZ 676, GZ911National Science Fund for Distinguished Young Scholars of China/2122562

A novel CO2-stable dual phase membrane with high oxygen permeability

By cobalt-doping of the mixed conducting phase PSFC, a good combination of high CO2 stability and high oxygen permeability is obtained for the 60 wt% Ce0.9Pr0.1O2-delta d -40 wt% Pr0.6Sr0.4Fe0.5Co0.5O3-delta (CP-PSFC) dual phase membrane, which suggests that CP-PSFC is a promising membrane for industrial applications in the oxyfuel process for CO2 capture