In the last decade the ns 2 cations (e.g., Pb 2+ and Sn 2+ ) based halides have emerged as one of the most exciting new classes of optoelectronic materials, as exemplified by for instance hybrid perovskite solar absorbers. These materials not only exhibit unprecedented performance in some cases, but they also appear to break new ground with their unexpected properties, such as extreme tolerance to defects. However, because of the relatively recent emergence of this class of materials, there remain many yet to be fully explored compounds. Here we assess a series of bismuth/antimony oxyhalides and chalcohalides using consistent first principles methods to ascertain their properties and obtain trends. Based on these calculations, we identify a subset consisting of three types of compounds that may be promising as solar absorbers, transparent conductors, and radiation detectors. Their electronic structure, connection to the crystal geometry, and impact on band-edge dispersion and carrier effective mass are discussed. Table S1. Space group, electronic band gaps, effective masses of carriers and formation energy ∆ of the 31 bismuth/antimony oxyhalides and chalcohalides considered in the current work. For the effective masses, the "*" means a very large number.

In this work, we investigate the electrochemical properties of Ba8Al y Ge46–y (y = 0, 4, 8, 12, 16) clathrates prepared by arc-melting. These materials have cage-like structures with large cavity volumes and can also have vacancies on the Ge framework sites, features which may be used to accommodate Li. Herein, a structural, electrochemical, and theoretical investigation is performed to explore these materials as anodes in Li-ion batteries, including analysis of the effect of the Al content and framework vacancies on the observed electrochemical properties. Single-crystal X-ray diffraction (XRD) studies indicate the presence of vacancies at the 6c site of the clathrate framework as the Al content decreases, and the lithiation potentials and capacities are observed to decrease as the degree of Al substitution increases. From XRD, electrochemical, and transmission electron microscopy analysis, we find that all of the clathrate compositions undergo two-phase reactions to form Li-rich amorphous phases. This is different from the behavior observed in Si clathrate analogues, where there is no amorphous phase transition during electrochemical lithiation nor discernible changes to the lattice constant of the bulk structure. From density functional theory calculations, we find that Li insertion into the three framework vacancies in Ba8Ge43 is energetically favorable, with a calculated lithiation voltage of 0.77 V versus Li/Li+. However, the calculated energy barrier for Li diffusion between vacancies and around Ba guest atoms is at least 1.6 eV, which is too high for significant room-temperature diffusion. These results show that framework vacancies in the Ge clathrate structure are unlikely to significantly contribute to lithiation processes unless the Ba guest atoms are absent, but suggest that guest atom vacancies could open diffusion paths for Li, allowing for empty framework positions to be occupied.

A series of novel red-emitting Sr1.7Zn0.3CeO4:Eu(3+) phosphors were synthesized through conventional solid-state reactions. The powder X-ray diffraction patterns and Rietveld refinement verified the similar phase of Sr1.7Zn0.3CeO4:Eu(3+) to that of Sr2CeO4. The photoluminescence spectrum exhibits that peak located at 614 nm ((5)D0-(7)F2) dominates the emission of Sr1.7Zn0.3CeO4:Eu(3+) phosphors. Because there are two regions in the excitation spectrum originating from the overlap of the Ce(4+)-O(2-) and Eu(3+)-O(2-) charge-transfer state band from 200 to 440 nm, and from the intra-4f transitions at 395 and 467 nm, the Sr1.7Zn0.3CeO4:Eu(3+) phosphors can be well excited by the near-UV light. The investigation of the concentration quenching behavior, luminescence decay curves, and lifetime implies that the dominant mechanism type leading to concentration quenching is the energy transfer among the nearest neighbor or next nearest neighbor activators. The discussion about the dependence of photoluminescence spectra on temperature shows the better thermal quenching properties of Sr1.7Zn0.3CeO4:0.3Eu(3+) than that of Sr2CeO4:Eu(3+). The experimental data indicates that Sr1.7Zn0.3CeO4:Eu(3+) phosphors have the potential as red phosphors for white light-emitting diodes.

Be our guest! Silicon clathrate with sodium guest atoms is studied as a potential anode material for lithium‐ion batteries. An electrochemical, structural, and first‐principles analysis is conducted to understand the phase changes occurring upon lithium insertion and removal from these cage‐like silicon structures.

A facile and scalable solution-based, spray pyrolysis synthesis technique was used to synthesize individual carbon nanospheres with specific surface area (SSA) up to 1106 m(2)/g using a novel metal-salt catalyzed reaction. The carbon nanosphere diameters were tunable from 10 nm to several micrometers by varying the precursor concentrations. Solid, hollow, and porous carbon nanospheres were achieved by simply varying the ratio of catalyst and carbon source without using any templates. These hollow carbon nanospheres showed adsorption of to 300 mg of dye per gram of carbon, which is more than 15 times higher than that observed for conventional carbon black particles. When evaluated as supercapacitor electrode materials, specific capacitances of up to 112 F/g at a current density of 0.1 A/g were observed, with no capacitance loss after 20,000 cycles.

Aqueous zinc-ion batteries (ZIBs) with metallic Zn anodes have emerged as promising candidates for large-scale energy storage systems due to their inherent safety and competitive capacity. However, challenges of Zn anodes, including dendrite growth and side reactions, impede the commercialization of ZIBs. The regulation of the Zn/electrolyte interphase is a feasible method to achieve high-performance ZIBs with prolonged lifespan and high reversibility. Considering the as-made artificial interphase is the result of a combination of protection materials, protection mechanisms, and construction techniques, this review comprehensively summarizes the recent progress of interphase modulation and provides a systematic guideline for constructing ideal artificial layers. In addition to revealing the entanglement relationship between the failure behaviors of Zn anodes and timely concluding the emerging protection mechanisms for stable Zn/electrolyte interphase, this review also evaluates the constructing techniques in regard of commercialization, including engineering workflow, strength, shortcoming, applicable materials, and protection effect, aiming to pave the way to practical application. Finally, this review presents noteworthy points of ideal artificial layer. It is expected that this review can enlighten researchers to not only explore ideal interphases of Zn anodes for practical application, but also design other metal anodes in aqueous batteries with similar failure behaviors.

Silicon clathrates contain cage‐like structures that can encapsulate various guest atoms or molecules. An electrochemical evaluation of type I silicon clathrates based on Ba8AlySi46−y as the anode material for lithium‐ion batteries is presented here. Postcycling characterization with nuclear magnetic resonance and X‐ray diffraction shows no discernible structural or volume changes even after electrochemical insertion of 44 Li (≈1 Li/Si) into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from large volume changes. The electrochemical reactions are proposed to occur as single phase reactions at approximately 0.2 and 0.4 V versus Li/Li+ during lithiation and delithiation, respectively, distinct from diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g−1 at a 5 mA g−1 rate were observed for silicon clathrate with composition Ba8Al8.54Si37.46, corresponding to ≈1.18 Li/Si. These results show that silicon clathrates could be promising durable anodes for lithium‐ion batteries.

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