Hydrogen-rich compounds are considered most likely to achieve room-temperature superconductivity since the critical temperature (T c) above 250 K was observed in lanthanum hydride. Exploring the high-temperature superconductivity in rare-earth metal hydrides becomes very interesting. Based on the particle swarm optimization for crystal structures and first-principles calculations, we investigate the crystal structures, phase stability, metallization, and possible superconducting properties of terbium hydride (TbH n , n = 1 – 12) under pressure. Our results show that terbium hydride is a potential high-temperature superconductor under high pressures. It stably exists at different pressure conditions by adjusting the H content. Specifically, the H atomic cage structure can be observed in most terbium hydrides, and the number of H atoms in the cage sublattice increases with the stoichiometry of H in TbH n . We demonstrate that the high T c value is closely related to this cage sublattice and it increases with increasing H content in terbium hydride. The highest T c above 270 K is predicted in TbH10 at 250 GPa for Fm3̅m and 310 GPa for R3̅m space group. This result indicates that the superconductivity with T c close to or beyond lanthanum hydride can be achieved in other rare-earth metal hydrides.

Solid methane doped by beryllium is superconducting at low pressures and its critical temperature can reach 30 K.

No abstract

Because of the high voltage and low cost, potassium-ion batteries have become a hotspot in the research of rechargeable batteries. In this paper, the electrochemical properties of poly-p-phenylenes are studied based on first-principles calculations. Poly-p-phenylenes are predicted to be promising intercalation-type anode materials for potassium-ion batteries that are superior to graphite. The results show that potassium ions can intercalate into poly-p-phenylenes without significant phase change. The anode is predicted to have a small volume expansion ratio of <60% and a high theoretical specific capacity of >800 mA h/g. The electron transfer from potassium to organic molecules results in a good electrical conductivity and a low average open-circuit voltage. Additionally, the low diffusion barrier of potassium ions in poly-p-phenylenes implies a rapid charge/discharge rate performance. Our results suggest that poly-p-phenylenes are promising anode materials for potassiumion batteries.

To explore the high-temperature superconductor at low pressures, we have investigated the crystal structures, electronic properties, and possible superconductivity in the case of methane (CH4) doped by lithium in the pressure range of [Formula: see text][Formula: see text]GPa, based on the first-principles calculations. The results show that Li-intercalated CH4 (Lix(CH4)[Formula: see text]) can realize metallization and superconductivity at low pressures, even 5[Formula: see text]GPa. We find that there is a charge transfer between Li and CH4, but the metallization is driven by the change of crystal field induce by doping instead of charge transfer. The critical temperture is predicted from 3.8[Formula: see text]K at 5[Formula: see text]GPa for LiCH4 to 12.1[Formula: see text]K at 100[Formula: see text]GPa for Li(CH4)4. The low-pressure superconductivity of Lix(CH4)[Formula: see text] can be further optimized by adjusting component and pressure.

Efficient exciton-to-charge generation from the introduction of non-fullerene acceptors (NFAs) has been an important breakthrough in organic solar cell (OSC) developments. However, low device fill factors (FFs) following significant free...

No abstract

No abstract