Fast crystal growth in deeply undercooled ZrTi melts.

We investigate the growth of crystals in Zr50Ti50 melts by classical molecular-dynamics simulations with an embedded atom method and a Stillinger-Weber potential model. Both models display fast solidification rates that can be captured by the transition state theory or the Ginzburg-Landau theory at small undercoolings. Fast crystal-growth rates are found to be affected by the pre-existing ordering in liquids, such as the body-centered cubic-like and icosahedral-like structures. The interface-induced ordering unveiled by the crystal-freezing method can explain the rate difference between these two models. However, these orderings fail to rationalize the temperature evolution of the growth rate at deep undercoolings. We correlate the growth kinetics with the detailed dynamical processes in liquids, finding the decoupling of hierarchic relaxation processes when collective motion emerges in supercooled liquids. We find that the growth kinetics is nondiffusive, but with a lower activation barrier corresponding to the structural relaxation or the cage-relative motion in ZrTi melts. These results explore a new relaxation mechanism for the fast growth rate in deeply undercooled liquids.

Fringe-width encoded patterns for 3D surface profilometry.

This paper presents a new fringe projection method for surface-shape measurement that uses novel fringe-width encoded fringe patterns. Specifically, the projection patterns are adjusted with the width of the fringe as the codeword. The wrapped phase with coding information is obtained by using the conventional wrapped phase calculation method, and the fringe order can be identified from the wrapped phase. After the fringe order is corrected based on the region growing algorithm, the fringe order and the wrapped phase can be directly used to reconstruct the surface. Static and dynamic measurements demonstrated the ability of the method to perform 3D shape measurement with only three projected patterns, single camera and projector in the least case.

High-resolution few-pattern method for 3D optical measurement.

Accurately and quickly obtaining the three-dimensional (3D) shape information of objects has become increasingly important in various scientific fields. However, simultaneously achieving the high-resolution and high-speed 3D shape measurement of unknown objects remains challenging in practice. In this Letter, we propose a novel variant shifting-phase method for 3D optical measurement. Based on a digital fringe projection system, the method performs a point-wise high-resolution measurement of objects by projecting only four intensity-coded patterns. We can retrieve the wrapped phases and their corresponding fringe orders simultaneously from these four patterns, and do not require any pre-acquired information of the object. The experimental results successfully demonstrate the effectiveness of the easy-to-operate method.

Fixed window aggregation AD-census algorithm for phase-based stereo matching.

Phase-based stereo matching (PSM) is a vital step in binocular structured light. PSM is hard to strike a balance between efficiency and accuracy, especially because of the absolute phase matrix's (APM) double data type. It means that PSM needs more run time and memory than conventional intensity images' stereo matching. In this paper, we propose a modified absolute difference (AD)-Census algorithm called the fixed window aggregation AD-Census (FWA-AD-Census) to balance the contradiction between efficiency and accuracy in PSM. The FWA-AD-Census aggregates matching cost in a fixed support window instead of an adaptive support window in AD-Census. We analyze the reason why PSM is more suitable to aggregate the matching cost in a fixed support window. Simulations and experiments are conducted to verify the FWA-AD-Census's performances by comparing the FWA-AD-Census with two other local stereo matching algorithms. One is the AD-Census, which is more accurate but less efficient. Its matching cost is aggregated in an adaptive support window. Another is the sum of absolute difference (SAD), which is more efficient but less accurate, and its matching cost is aggregated in a fixed support window. Theoretical analysis and experimental results both indicate that the proposed algorithm can achieve similar accuracy to the AD-Census with less run time.

Zero-Strain Na3 V2 (PO4 )2 F3 @Rgo/CNT Composite as a Wide-Temperature-Tolerance Cathode for Na-Ion Batteries with Ultrahigh-Rate Performance.

Sodium-ion batteries (SIBs) are widely considered a hopeful alternative to lithium-ion battery technology. However, they still face challenges, such as low rate capability, unsatisfactory cycling stability, and inferior variable-temperature performance. In this study, a hierarchical Na3 V2 (PO4 )2 F3 (NVPF) @reduced graphene oxide (rGO)/carbon nanotube (CNT) composite (NVPF@rGO/CNT) is successfully constructed. This composite features 0D Na3 V2 (PO4 )2 F3 nanoparticles are coated by a cross-linked 3D conductive network composed of 2D rGO and 1D CNT. Furthermore, the intrinsic Na+ storage mechanism of NVPF@rGO/CNT through comprehensive characterizations is unveiled. The synthesized NVPF@rGO/CNT exhibits fast ionic/electronic transport and excellent structural stability within wide working temperatures (-40-50 °C), owing to the zero-strain NVPF and the coated rGO/CNT conductive network that reduces diffusion distance for ions and electrons. Moreover, the stable integration between NVPF and rGO/CNT enables outstanding structural stability to alleviate strain and stress induced during the cycle. Additionally, a practice full cell is assembled employing a hard carbon anode paired with an NVPF@rGO/CNT cathode, which provides a decent capacity of 105.2 mAh g-1 at 0.2 C, thereby attaining an ideal energy density of 242.7 Wh kg-1 . This work provides valuable insights into developing high-energy and power-density cathode materials for SIBs.

Vapor-deposited digenite in Chang'e-5 lunar soil.

Frequent impacts on the Moon have changed the physical and chemical properties of the lunar regolith, with new materials deposited from the impact-induced vapor phase. Here, we combined nanoscale chemical and structural analysis to identify the mineral digenite (4Cu2S·CuS) in Chang'e-5 lunar soil. This is the first report of digenite in a lunar sample. The surface-correlated digenite phase is undifferentiated in distribution and compositionally distinct from its hosts, suggesting that it originated from vapor-phase deposition. The presence of an Al-rich impact glass bead suggests that a thermal effect provided by impact ejecta is the main heat source for the evaporation of Cu-S components from a cupriferous troilite precursor, and the digenite condensed from these Cu-S vapors. A large pure metallic iron (Fe0) particle and high Cu content within the studied Cu-Fe-S grain suggest that this grain was most likely derived from a highly differentiated and reduced melt.

High-Performance Aqueous Zinc-Ion Batteries Based on Multidimensional V2 O3 Nanosheets@Single-Walled Carbon Nanohorns@Reduced Graphene Oxide Composite and Optimized Electrolyte.

The drawbacks of poor electronic conductivity and structural instability during the cycling process limit the electrochemical property of vanadium-based cathode materials for aqueous zinc-ion batteries. In addition, continuous growth and accumulation of zinc dendrites can puncture the separator and cause an internal short circuit in the battery. In this work, a unique multidimensional nanocomposite is designed by a facile freeze-drying method with subsequent calcination, consisting of V2 O3 nanosheets and single-walled carbon nanohorns (SWCNHs) crosslinked together and wrapped by reduced graphene oxide (rGO). The multidimensional structure can largely enhance the structural stability and electronic conductivity of the electrode material. Besides, additive Na2 SO4 in the ZnSO4 aqueous electrolyte not only prevents the dissolution of cathode materials but also suppresses the Zn dendrite growth. After considering the influence of additive concentration on ionic conductivity and electrostatic force for electrolyte, V2 O3 @SWCNHs@rGO electrode delivers a high initial discharge capacity of 422 mAh g-1 at 0.2 A g-1 and a high discharge capacity of 283 mAh g-1 after 1000 cycles at 5 A g-1 in 2 m ZnSO4 + 2 m Na2 SO4 electrolyte. Experimental techniques reveal that the electrochemical reaction mechanism can be expressed as the reversible phase transformation between V2 O5 and V2 O3 with Zn3 (VO4 )2 .

Characteristics of Solar Wind Radiation Damage in Lunar Soil: PAT and TEM Study.

Irradiation structural damage (e.g., radiation tracks, amorphous layers, and vesicles) is widely observed in lunar soil grains. Previous experiments have revealed that irradiation damage is caused by the injection of solar wind and solar flare energetic particles. In this study, cordierite and gabbro were selected as analogs of shallow and deep excavated lunar crust materials for proton irradiation experiments. The fluence was 1.44 ± 0.03 × 1018 H+/cm2, which is equivalent to 102 years of average solar wind proton implantation on the Moon. Before and after irradiation, structural damage in samples is detected by slow positron annihilation technology (PAT), Doppler broadening (DB) measurement, focused ion beam (FIB), and transmission electron microscopy (TEM). The DB results showed the structural damage peaks of irradiated gabbro and cordierite were located at 40 and 45 nm. Hydrogen diffused to a deeper region and it reached beyond depths of 150 and 136 nm for gabbro and cordierite, respectively. Hydrogen atoms occupied the original vacancy defects and formed vacancy sites-hydrogen atom complexes, which affected the annihilation of positrons with electrons in the vacancy defects. All of the DB results were validated by TEM. This study proves that the positron annihilation technique has an excellent performance in the detection of defects in the whole structure of the sample. In combination with TEM and other detection methods, this technology could be used for the detection of structural damage in extraterrestrial samples.

Fully Active Bimetallic Phosphide Zn0.5Ge0.5P: A Novel High-Performance Anode for Na-Ion Batteries Coupled with Diglyme-Based Electrolyte.

Metal phosphides are promising candidates for sodium-ion battery (SIB) anode owing to their large capacities with suitable redox potential, while the reversibility and rate performances are limited due to some electrochemically inactive transition-metal components and sluggish reaction kinetics. Here, we report a fully active bimetallic phosphide Zn0.5Ge0.5P anode and its composite (Zn0.5Ge0.5P-C) with excellent performance attributed to the Zn, Ge, and P components exerting their respective Na-storage merit in a cation-disordered structure. During Na insertion, Zn0.5Ge0.5P undergoes an alloying-type reaction, along with the generation of NaP, Na3P, NaGe, and NaZn13 phases, and the uniform distribution of these phases ensures the electrochemical reversibility during desodiation. Based on this reaction mechanism, excellent electrochemical properties such as a high reversible capacity of 595 mAh g-1 and an ultrafast charge-discharge capability of 377.8 mAh g-1 at 50C for 500 stable cycles were achieved within the Zn0.5Ge0.5P-C composite in a diglyme-based electrolyte. This work reveals the Na-storage reaction mechanism within Zn0.5Ge0.5P and offers a new perspective on designing high-performance anodes.

Sub-microscopic magnetite and metallic iron particles formed by eutectic reaction in Chang'E-5 lunar soil.

Ferric iron as well as magnetite are rarely found in lunar samples, and their distribution and formation mechanisms on the Moon have not been well studied. Here, we discover sub-microscopic magnetite particles in Chang'E-5 lunar soil. Magnetite and pure metallic iron particles are embedded in oxygen-dissolved iron-sulfide grains from the Chang'E-5 samples. This mineral assemblage indicates a FeO eutectoid reaction (4FeO = Fe3O4 + Fe) for formation of magnetite. The iron-sulfide grains' morphology features and the oxygen's distribution suggest that a gas-melt phase reaction occurred during large-impact events. This could provide an effective method to form ubiquitous sub-microscopic magnetite in fine lunar soils and be a contributor to the presentation of ferric iron on the surface of the Moon. Additionally, the formation of sub-microscopic magnetite and metallic iron by eutectoid reaction may provide an alternative way for the formation of magnetic anomalies observed on the Moon.

Chang'E-5 samples reveal high water content in lunar minerals.

The formation and distribution of lunar surficial water remains ambiguous. Here, we show the prominence of water (OH/H2O) attributed to solar wind implantation on the uppermost surface of olivine, plagioclase, and pyroxene grains from Chang'E-5 samples. The results of spectral and microstructural analyses indicate that solar wind-derived water is affected by exposure time, crystal structure, and mineral composition. Our estimate of a minimum of 170 ppm water content in lunar soils in the Chang'E-5 region is consistent with that reported by the Moon Minerology Mapper and Chang'E-5 lander. By comparing with remote sensing data and through lunar soil maturity analysis, the amount of water in Chang'E-5 provides a reference for the distribution of surficial water in middle latitude of the Moon. We conclude that minerals in lunar soils are important reservoirs of water, and formation and retention of water originating from solar wind occurs on airless bodies.