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Different cadmium (Cd)-accumulated rice genotypes (Erjiunan 1 and Fupin 36) were used to explore the effect of rice rhizosphere aeration on Cd uptake and accumulation. Aeration in the nutrient solution influenced the agronomic characteristics induced by Cd-stress, such as the increases of rice root length and root vigor, but the reductions of plant height and shoot dry weight. Aeration also alleviated the decreasing effects of Cd stress on antioxidant enzyme activities and soluble protein, malonaldehyde and nicotianamine contents in rice. Moreover, with aeration treatment, the accumulation and bioavailability of metal elements changed significantly, with a Cd increase and an Fe reduction in both rice genotypes. In addition, at the molecular level, aeration upregulated the expression of Fe-inducible genes (such as OsIRT1, OsNRAMP1, OsYSL15 and OsNAS3). Furthermore, as a Cd2+/Fe2+ transporter, the high transcription level of OsNRAMP1 can elevate the Cd uptake and translocation in rice due to the Fe reduction caused by aeration and Cd-exposure, which indicated that OsNRAMP1 might play a crucial role in the effect of aeration on Cd uptake and accumulation.

P2-type Na2/3Ni1/3Mn2/3O2 is an air-stable cathode material for sodium-ion batteries. However, it suffers irreversible P2-O2 phase transition in 4.2-V plateau and shows poor cycling stability and rate capability within this plateau. To evaluate the practicability of this material in 2.3–4.1 V voltage range, single-crystal micro-sized P2-type Na2/3Ni1/3Mn2/3O2 with high rate capability and cycling stability is synthesized via polyvinylpyrrolidone (PVP)-combustion method. The electrochemical performance is evaluated by galvanostatic charge-discharge tests. The kinetics of Na+ intercalation/deintercalation is studied detailly with potential intermittent titration technique (PITT), galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV). The discharge capacity at 0.1 C in 2.3–4.1 V is 87.6 mAh g−1. It can deliver 91.5% capacity at 40 C rate and keep 89% after 650 cycles at 5C. The calculated theoretical energy density of full cell with hard carbon anode is 210 Wh kg−1. The moderate energy density associated with high power density and long cycle life is acceptable for load adjustment of new-energy power, showing the prospect of practical application.

Using a materials genome approach on the basis of the density functional theory, we have formulated a new class of inorganic electrolytes for fast diffusion of Li+ ions, through fine-tuning of lattice chemistry of anti-perovskite structures. Systematic modelling has been carried out to elaborate the structural stability and ion transportation characteristics in Li3AX based cubic anti-perovskite, through alloying on the chalcogen lattice site (A) and alternative occupancy of the halogen site (X). In addition to identifying effective ways for reduction of diffusion barriers for Li+ ions in anti-perovskite phases via suitable designation of lattice occupancy, the current theoretical study leads to discovery and synthesis of a new phase with a double-anti-perovskite structure, Li6OSI2 (or Li3O0.5S0.5I). Such a new compound is of fairly low activation barrier for Li+ diffusion, together with a wide energy band gap to hinder conduction of electrons.

It is of great importance to develop inorganic solid electrolytes with high ionic conductivity, thus enabling solid state Li-ion batteries to address the notorious safety issue about the current technology due to use of highly flammable liquid organic electrolytes. On the basis of systematic first principles modelling, we have formulated new inorganic electrolytes with ultra-low activation energies for long-distance diffusion of Li+ ions, through alloying in the cubic Li6PA5X chalcogenides (chalcogen A; halogen X). We find that the long-distance transportation of Li+ is dictated by inter-octahedral diffusion, as the activation energy for Li+ to migrate over a Li6A octahedron is minimal. The inter-octahedral diffusion barrier for Li+ is largely dependent on the interaction with chalcogen anions in the compound. Radical reduction of diffusion barrier for Li+ ions can be realized through isovalent substitution of S using elements of lower electronegativity, together with smaller halogen ions on the X site.

Invited talk; International audience

Thermodynamic assessment of the Ti-Al-V system has been carried out using the Thermo-Calc. The database resulting from the present work gives calculated phase equilibria which are in good agreement with experimentally determined phase diagrams. The beta→B2 ordering process has been modelled as a second order transformation and an ordering model for the ternary B2 phase was proposed, which makes the Gibbs energy of the B2 phase converge to that of the disordered beta phase at the beta→B2 ordering temperature. The calculation of phase diagrams and beta→B2 ordering temperatures can thus be made from the same thermodynamic database. The predicted B2/beta boundary for Al-V rich alloys is in good agreement with experiments, while there is a discrepancy between the predicted and the experimentally determined beta/B2 boundaries for Ti-V rich alloys, probably due to the use of composition-independent w(2)/w(1) ratios in the present B2 model. It has been predicted that alpha2+gamma cannot be in equilibrium with disordered beta. Phase equilibria in arc-melted ingots of Ti-Al-V alloys have been studied using TEM, SEM and EDX analysis. Thermodynamic modelling has also proved to be a powerful approach to predict the as-solidified microstructures of these alloy ingots, even though they did not solidify under equilibrium conditions. Experiments have been performed to study metastable phase transformations in melt spun Ti-Al-V alloy ribbons. The results show that both thermodynamics and kinetics play an important role for phase selection in the alloy ribbons. Transient nucleation effects appear to be dominant in ≤50mum thick alloy ribbons. Large cooling rates tend to: (a) favour the primary phase selection in the order of: gamma>alpha>beta, (b) suppress solid state transformations, (c) lower the effective alpha →alpha2 ordering temperature, (d) to suppress completely the alpha →alpha2 ordering process, and (e) lead to massive transformations such as alpha→gammam and alpha →alpha2. An ordered o phase has been observed in the metastable B2 phase in Ti-Al-V alloys. Diffuse o formation has been observed for the first time in the disordered metastable P phase in V-50A1 and V-50Al+(≤30at%Ti) alloys. It has been shown that the o stability is related to both the unit cell volume (Vbeta) and the number of free electrons (e) per atom of the metastable beta/B2 phase. Small values of (e/Vbeta) lead to the formation of an w phase closer to the 3-D crystalline o structure.

The fabrication of high-performance, low-cost photocatalysis materials, which absorb in the visible-light region, is of significance for their practical applications. A Ti2O@TiO2 (rutile) core-shell structure was fabricated through dehydrogenation and oxidation from TiH2. Thermal analysis indicates that a bimodal oxidation behavior accounts for the formation of a bi-phasic composite. The response of the composite under UV and visible light was measured by PL (photoluminescence) spectra and a photo-degradation test. A pronounced improvement in photo-degradation performance is attributed to the synergistic function of exciton separation of the core-shell structure and the visible light response of the Ti2O