Articles you may be interested inLarge magnetic entropy change associated with the weakly first-order paramagnetic to ferrimagnetic transition in antiperovskite manganese nitride CuNMn3 J. Appl. Phys. 116, 033902 (2014); 10.1063/1.4890223Effect of hydrostatic pressure on magnetic entropy change and critical behavior of the perovskite manganite La0.4Bi0.3Sr0.3MnO3

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Functionalized MXenes hold promises in a variety of applications in which the dispensable functional groups are mixed. The functionalization is spontaneously realized through competitive adsorption of active species on the MX matrix during the acid etching process of MAX phases. Nevertheless, the knowledge of proportion and distribution of functional groups on MXenes, i.e., surface structures, is still limited. By high-throughput computation screening, ground-state stable structures of four kinds of typical MXenesTi 2 CT x , Ti 3 C 2 T x , Nb 2 CT x , and Nb 4 C 3 T x (T = O, F, and OH)with mixed functional group compositions are figured out for the first time. The multicomponent functional group patterns definitely demonstrate an obvious feature of spatial mixing at a given component. However, the heterogeneous structure has a near linear dependence on the functional group components in terms of free energy. Most functionalized MXenes are dynamically stable except for Nb 2 CF 2 and Nb 2 C(OH) 2 due to their competing displacive counterparts. Last but not least, Raman spectra of the four kinds of MXenes confirm the predicted stable surface structures of MXenes. This study provides a clear fundamental basis for understanding the surface structures of MXenes.

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High interfacial resistance between a cathode and solid electrolyte (SE) has been a long-standing problem for all-solid-state batteries (ASSBs). Though thermodynamic approaches suggested possible phase transformations at the interfaces, direct analyses of the ionic and electronic states at the solid/solid interfaces are still crucial. Here, we used our newly constructed scheme for predicting heterogeneous interface structures via the swarm-intelligence-based crystal structure analysis by particle swarm optimization method, combined with density functional theory calculations, and systematically investigated the mechanism of Li-ion (Li+) transport at the interface in LiCoO2 cathode/β-Li3PS4 SE, a representative ASSB system. The sampled favorable interface structures indicate that the interfacial reaction layer is formed with both mixing of Co and P cations and mixing of O and S anions. The calculated site-dependent Li chemical potentials μLi(r) and potential energy surfaces for Li+ migration across the interfaces reveal that interfacial Li+ sites with higher μLi(r) values cause dynamic Li+ depletion with the interfacial electron transfer in the initial stage of charging. The Li+-depleted space can allow oxidative decomposition of SE materials. These pieces of evidence theoretically confirm the primary origin of the observed interfacial resistance in ASSBs and the mechanism of the resistance decrease observed with oxide buffer layers (e.g., LiNbO3) and oxide SE. The present study also provides a perspective for the structure sampling of disordered heterogeneous solid/solid interfaces on the atomic scale.