The development of capable of simultaneously modulating the sluggish electrochemical kinetics, shuttle effect, and lithium dendrite growth is a promising strategy for the commercialization of lithium-sulfur batteries. Consequently, an elaborate preparation method is employed to create a host material consisting of multi-channel carbon microspheres (MCM) containing highly dispersed heterostructure Fe3O4-FeTe nanoparticles. The Fe3O4-FeTe@MCM exhibits a spontaneous built-in electric field (BIEF) and possesses both lithophilic and sulfophilic sites, rendering it an appropriate host material for both positive and negative electrodes. Experimental and theoretical results reveal that the existence of spontaneous BIEF leads to interfacial charge redistribution, resulting in moderate polysulfide adsorption which facilitates the transfer of polysulfides and diffusion of electrons at heterogeneous interfaces. Furthermore, the reduced conversion energy barriers enhanced the catalytic activity of Fe3O4-FeTe@MCM for expediting the bidirectional sulfur conversion. Moreover, regulated Li deposition behavior is realized because of its high conductivity and remarkable lithiophilicity. Consequently, the battery exhibited long-term stability for 500 cycles with 0.06% capacity decay per cycle at 5 C, and a large areal capacity of 7.3 mAh cm(-2) (sulfur loading: 9.73 mg cm(-2)) at 0.1 C. This study provides a novel strategy for the rational fabrication of heterostructure hosts for practical Li-S batteries.

Pulsed solid-state lasers comprise 2D materials as saturable absorbers that contain transparent windows of the atmosphere and characteristic fingerprint spectra of several vital molecules that are significant in various applications and research. Over the past few decades, significant progress has been made in the development of narrow pulse width, high energy, high average output power, high efficiency, and simple construction of passively Q-switched and mode-locked lasers with 2D materials as saturable absorbers. This review summarizes the development of 2D materials, including graphene, transition metal dichalcogenides, black phosphorus, topological insulators, and MXenes, as modulator devices for solid-state lasers owing to their broadband operation, excellent nonlinear optical response, low recovery time, ultrafast dynamic processing, and easy fabrication. Then, some new emerging and representative applications of pulsed solid-state lasers are introduced and illustrated such as laser surgery, material processing, and lidar. Finally, future challenges and perspectives of pulsed solid-state lasers with 2D materials-based saturable absorbers are analyzed and addressed. The rapid development of pulsed solid-state lasers with the continuous improvement of modulation technology is expected to expand opportunities for application in industry, scientific, medical, and other areas. Currently, important progress is achieved in the development of narrow pulse width, high average output power, repetition rate, and simple construction of pulsed solid-state laser based on 2D material saturable absorptions. This review summarizes the properties and applications of the pulsed solid-state lasers based on 2D material saturable absorptions, as well as future challenges and directions. image

We report experimental discovery of tantalum polyhydride superconductor. It was synthesized under high-pressure and high-temperature conditions using diamond anvil cell combined with in situ high-pressure laser heating techniques. The superconductivity was investigated via resistance measurements at pressures. The highest superconducting transition temperature T c was found to be ∼ 30 K at 197 GPa in the sample that was synthesized at the same pressure with ∼ 2000 K heating. The transitions are shifted to low temperature upon applying magnetic fields that support the superconductivity nature. The upper critical field at zero temperature μ 0 H c2(0) of the superconducting phase is estimated to be ∼ 20 T that corresponds to Ginzburg–Landau coherent length ∼ 40 Å. Our results suggest that the superconductivity may arise from I 4 ¯ 3 d phase of TaH3. It is, for the first time to our best knowledge, experimental realization of superconducting hydrides for the VB group of transition metals.

The binary polyhydrides of heavy rare earth lutetium that shares a similar valence electron configuration to lanthanum have been experimentally discovered to be superconductive. The lutetium polyhydrides were successfully synthesized at high pressure and high temperature conditions using a diamond anvil cell in combinations with the in-situ high pressure laser heating technique. The resistance measurements as a function of temperature were performed at the same pressure of synthesis in order to study the transitions of superconductivity (SC). The superconducting transition with a maximum onset temperature (Tc) 71 K was observed at pressure of 218 GPa in the experiments. The Tc decreased to 65 K when pressure was at 181 GPa. From the evolution of SC at applied magnetic fields, the upper critical field at zero temperature μ _0H_c2(0) was obtained to be ∼36 T. The in-situ high pressure X-ray diffraction experiments imply that the high Tc SC should arise from the Lu4H23 phase with Pm3 n symmetry that forms a new type of hydrogen cage framework different from those reported for previous light rare earth polyhydride superconductors.

Superconductivity (SC) was experimentally observed for the first time in antimony polyhydride. The diamond anvil cell combined with laser heating system was used to synthesize the antimony polyhydride sample at high pressure and high temperature conditions. In-situ high pressure transport measurements as function of temperature with applied magnet are performed to study the SC properties. It was found that the antimony polyhydride samples show superconducting transition with critical temperature Tc 116 K at 184 GPa. The investigation of SC at magnetic field revealed that the superconducting coherent length 40 angstroms based on Ginzburg Landau (GL) equation. Antimony polyhydride superconductor has the second highest Tc in addition to sulfur hydride among the polyhydrides of elements from main group IIIA to VIIA in periodic table.

Superconductivity is one of most intriguing quantum phenomena, and the quest for elemental superconductors with high critical temperature ( T c ) is of great scientific significance due to their relatively simple material composition and the underlying mechanism. Here we report the experimental discovery of densely compressed scandium (Sc) becoming the first elemental superconductor with T c breaking into 30 K range, which is comparable to the T c values of the classic La–Ba–Cu–O or LaFeAsO superconductors. Our results show that T c onset of Sc increases from ∼ 3 K at around 43 GPa to ∼ 32 K at about 283 GPa ( T c zero ∼ 31 K), which is well above liquid neon temperature. Interestingly, measured T c shows no sign of saturation up to the maximum pressure achieved in our experiments, indicating that T c may be even higher upon further compression.

Searching for superconductivity with Tc near room temperature is of great interest both for fundamental science & potential applications. Here we report the experimental discovery of superconductivity with maximum critical temperature(Tc) above 210 K in calcium superhydrides, the third type hydride experimentally showing superconductivity above 200K in addition to sulfur hydride & rare earth hydride system. The materials are synthesized at the synergetic conditions of 160~190 GPa and ~2000K using diamond anvil cell combined with in-situ laser heating technique. The superconductivity was studied through in situ high pressure resistance measurements in applied magnetic field for the sample quenched from high temperature while maintained at the synthesized pressure. The upper critical field was estimated to be ~268T while the GL coherent length is ~11 Å. The in situ x ray diffractions with synchrotron suggest that the synthesized calcium hydrides are primarily composed of CaH6 while there also exist other calcium hydrids with different hydrogen.

It is challenging to search for high Tc superconductivity (SC) in transition metal elements wherein d electrons are usually not favored by conventional BCS theory. Here we report experimental discovery of surprising SC up to 310 GPa with Tc above 20 K in wide pressure range from 108 GPa to 240 GPa in titanium. The maximum Tconset above 26.2 K and zero resistance Tczero of 21 K are record high values hitherto achieved among element superconductors. The Hc2(0) is estimated to be ∼32 Tesla with coherence length 32 Å. The results show strong s-d transfer and d band dominance, indicating correlation driven contributions to high Tc SC in dense titanium. This finding is in sharp contrast to the theoretical predications based on pristine electron-phonon coupling scenario. The study opens a fresh promising avenue for rational design and discovery of high Tc superconductors among simple materials via pressure tuned unconventional mechanism.

We grew a series of NaFe 1− x V x As (0 ≤ x ≤ 0.03) single crystals and performed the measurements of resistance, magnetic susceptibility, and specific heat to study the superconducting phase diagram by doping V into NaFeAs. Both the structural and the spin-density-wave (SDW) transitions are slightly suppressed by V-doping. While superconducting transition temperature is enhanced to the maximum value of ∼ 15 K when the optimal doping level x = 0.007 and then is suppressed rapidly with further V-doping, displaying a small superconducting dome. Our results suggest that V-impurities should act as strong magnetic scattering centers which cause the sharp suppression of superconductivity in NaFe 1− x V x As.

In this work, we report on the discovery of the high-pressure phase of Ba2FeS3 with quasi one-dimensional (1D) spin chains, which was synthesized under high-pressure and high-temperature conditions. A systematic study was carried out via structural, transport, magnetic and thermodynamic measurements. The high-pressure phase of Ba2FeS3 (denoted by Ba2FeS3 (HP)) crystallizes in a K2AgI3 typed orthorhombic structure with the space group of Pnma (62) and the lattice parameters of a = 8.6831 (1) angstrom, b = 4.2973 (1) angstrom, and c = 17.0254 (2) angstrom, respectively, which consists of chains of corner-sharing FeS4 tetrahedra along the b axis. Ba2FeS3 (HP) undergoes a long-range antiferromagnetic transition at T-N similar to 56 K, above which the magnetic susceptibility curve exhibits a round hump behavior with the maximum temperature T-max similar to 110 K. In addition, the intrachain coupling J(intra) is about -18 K obtained by using the Wagner-Friedberg model. The specific heat data suggest that the total magnetic entropy change AS caused by the long-range ordering transition is only similar to 20% of the expected value for a S = 2 system. For comparison, the properties of K2CuCl3-typed Ba2FeS3 with similar quasi 1D spin chains were presented as well. Our results indicate that both compounds exhibit a typical feature expected for compounds with 1D spin chains. (C) 2020 Elsevier B.V. All rights reserved.

Elevated CO2 and temperature are expected to result in drought stress with increased intensity and frequency, yet our understanding of subsequent plant response is generally limited. The objective of this study was to investigate the impacts of elevated CO2 and temperature on physiological traits affecting drought tolerance of cotton plants (Gossypium hirsuarm). We grew cotton plants in the glasshouse under two CO2 treatments (C-a: 420 ppm; C-e: 640 ppm) and two temperature treatments (T-a: 32/24 degrees C; day/night; T-e : 36/28 degrees C; day/night) with adequate irrigation and fertilization. Plant allometry, leaf gas exchange and a suite of hydraulic characteristics (xylem resistance to drought-induced embolism in the leaf and stem, leaf tolerance to dehydration-induced loss of rehydration capacity, and water transport capacity of stem) were examined. Xylem anatomical traits of the leaf and stem were also examined to elucidate the structural basis for potential physiological adjustments. C-e increased canopy leaf area and decreased leaf level water loss at T-a, and decreased stomatal conductance and transpiration at both temperatures. Moreover, C-e significantly increased stem conductivity at T-a, but xylem tissue was less resistant to drought induced embolism. T-e altered the pattern of xylem conductivity and embolism resistance response to CO2, with the stem less hydraulically conductive while the xylem was more tolerant to embolism under C-e. The variation of stem conductivity and embolism resistance of the stem across CO2 and temperature treatments was likely to be partially explained by xylem anatomy. Overall, CO2 and temperature had interactive effects on traits associated with water relations of cotton, such that elevated CO2 compromised drought tolerance under ambient temperature, but these negative impacts were partially mitigated by elevated temperature.

In this work, we introduce the Architecture Tech for High-Pressure Experiments Net Assembly (ATHENA) package based on diamond anvil cells, combining both the deposition of specimens as well as the detection of probes on anvils layer by layer. The specimens are typically ~1 μm in thickness and very hard to manipulate with traditional hand skills. ATHENA represents an all-in-one package by accurately synergizing chip-like networks prepared using magnetic sputtering methods and guaranteeing well-designed dimensions, positions and perfect electric contacts. We apply ATHENA successfully to the study of lanthanum metal above 60 GPa, showing very sharp pressure-enhanced superconductivity and parabolic critical temperature (Tc) evolution as a function of pressure with pressure-enhanced itinerant behavior at normal state.

We reported the growth of Fe2As single crystals and the study of its physical properties via comprehensive measurements, such as transport properties under pressure and high-pressure synchrotron radiation X-ray diffraction. Fe2As is an antiferromagnetic metal with TN ~355 K. Within the pressure range of 100 GPa, no superconductivity was observed above 2 K. The abrupt drop in resistance from 21 to 31.7 GPa suggests a high-pressure phase transition happens. The high-pressure X-ray experiments indicate a new high-pressure phase appears, starting from 27.13 GPa. After the refinement of the high-pressure X-ray data, the pressure dependence of lattice constants of Fe2As (P4/nmm phase) was plotted and the bulk modulus B0 was obtained to be 168.6 GPa.