查看更多>>摘要：? 2022To analyze the effect of thermomechanical treatment on the superelasticity, phase transition behavior and elastocaloric properties of Ti-18Zr-11 Nb-3Sn alloys, several cold-rolled sheets were annealed at temperatures between 923 K and 1173 K. With increasing annealing temperature, the precipitated Zr5Sn3 phase in the samples gradually dissolves until it completely disappears. All samples undergo strain glass behavior, and the ideal freezing temperature T0 gradually decreases from 371.3 K to 195.3 K with increasing annealing temperature. Moreover, the superelasticity and elastocaloric working window can be widened to 110 K by adjusting the annealing temperature. The elastocaloric properties of the sample were obtained with an adiabatic temperature change of 2.5 K.
查看更多>>摘要：? 2022 Elsevier B.V.SrFe12O19 (SFO) nanofibers (NFs), CoEu0.02Fe1.98O4 (CEFO) NFs, and hard-soft (H/S) SrFe12O19 (SFO)/(CoEu0.02Fe1.98O4)x (CEFO) (x = 1.0, 1.5, 2.0, 2.5) nanofiber composites (NFCs) were produced via electrospinning approach. The X-ray powder diffraction (XRD) patterns for the studied compositions confirmed the coexistence of characteristics peaks of both phases (Sr-M-type hexaferrite and cubic spinel ferrite) without any impurity. The lattice parameters ‘a′ and ‘c′ for hexagonal SFO and ‘a′ for CEFO NFs are fluctuating with increasing the ratio of CEFO NFs. The surface of nanofibers showed fibers having some roughness and bumps. They are consisted of hexagonal particles belong to SFO mixed and fine cubic CEFO NFs. These observations were confirmed by SEM (Scanning electron microscopy) along with EDX (Energy dispersive X-ray) and HR-TEM (High resolution transmission electron microscopy). The fibers showed a non-uniform cross-section with diameter between 33 and 95 nm. Diffuse reflectance spectroscopic (DRS) investigations were performed on SrFe12O19 NFs, on soft CoEu0.02Fe1.98O4 NFs, and on H/S (SFO)/(CEFO) (x = 1.0, 1.5, 2.0, 2.5) NFCs. Tauc method provided the estimation of optical bandgap (Eg) of each sample. The magnitudes for Eg are in the range of 1.56–1.77 eV. The magnetic responses of all samples in external applied magnetic field (M-H) were recorded at ambient temperature (T = 300 K) and low temperature (T = 10 K). Diverse produced nanofiber composites do not display no kinks in the measured M-H curves at both temperatures. Moreover, a single intense peak was clearly observed in the curves of dM/dH vs. H. These results reflected that the degree of exchange-coupling between hard and soft phases is well achieved via the employment of the electrospinning technique. At ambient temperature, it was observed that the magnetization is improving while the coercivity is diminishing with the increase in H/S ratio. On the contrary, at T = 10 K, the rise of CoEu0.02Fe1.98O4 content within diverse H/S NFCs provokes a slight decline in magnetization and a great enlargement in coercivity. The plausible reasons for such tendencies were discussed.
查看更多>>摘要：? 2022 Elsevier B.V.Supercapacitors with outstanding merits including extraordinary cycle stability, safety and high power density are complementary energy storage devices to batteries. The construction of one-dimensional hierarchical ternary composites is conducive to the synergy between different materials, and can be used to assemble high-performance asymmetric supercapacitors. To this end, coaxial polyphosphazene (PZS)-coated MoO3 nanowires are used as the substrate, and CoFe layered double hydroxide (CoFe-LDH) or Ni(OH)2 is grown in-situ on the nanowires followed by high-heat treatment to form MoO3 NWs @ PZSC / CoFe2O4 and MoO3 NWs @ PZSC / NiO as the negative and positive electrodes, respectively, as confirmed by a series of spectroscopic measurements. Electrochemical characterizations confirm the excellent electrochemical performance of both electrode materials. The supercapacitors exhibit a potential window of 1.7 V in KOH aqueous electrolyte, with the maximum specific capacity of 48.55 mAh g?1 at 2 A g?1 and the energy density of 41.27 Wh kg?1 at 1707.72 W kg?1. This work provides an applicable approach to utilize the synergistic effect between PZSC and transition metal oxides in order to enhance the performance of supercapacitors.
查看更多>>摘要：? 2022The inverted organic solar cell (IOSC) supported on an optically transparent and mechanically flexible oxynitride/metal/oxynitride substrate is receiving increasing attention owing to its light weight, flexible, and cost-effective design, compared to the conventional oxide-based solar cells. To develop an efficient IOSC, technical issues related to charge carrier transport and the transmittance of the conventional oxide electrode need to be solved. Herein, we report a highly transparent cathode for a highly efficient inverted organic solar cell using InGaON/Ag–Ti/InGaON multilayer electrodes. The In2O3 and GaN targets are co-sputtered to fabricate the multicomponent conductive oxynitride films. The sheet resistance of InGaON in optimized sputtering conditions is about 53.63 Ω/□, with the transmittance of 88.12%. The optimal InGaON/Ag–Ti/InGaON configuration (35/12/35 nm) showed the low sheet resistance of 5.7 Ω/□, and higher transmittance of about 96.8% as a whole InGaON/Ag–Ti/InGaON electrode. The multilayer electrode showed superior mechanical property in bending and twisting for 10,000 cycles with no resistance change. Furthermore, the inverted organic solar cell with the deposited layers of InGaON/Ag–Ti/InGaON–ZnO–Active layer–MoO3–Ag exhibited the higher power conversion efficiency of 8.63%, indicating that the InGaON/Ag–Ti/InGaON cathode is a promising candidate for substitution for the conventional oxide electrode.
查看更多>>摘要：? 2022 Elsevier B.V.All-inorganic perovskite CsCu2I3 thin films have been prepared on Si(100) substrates by pulsed laser deposition technology. And the influence of the substrate temperatures on the morphology, structure and optical properties of the CsCu2I3 films was investigated by SEM, XRD, PL and absorption spectra. A prototype CsCu2I3/Si n-n heterojunction UV photodetection device was constructed with LiF/Al and Au Ohmic contact electrodes. The photodetector demonstrates excellent self-powered photoresponse performance with an on/off ratio of ~2150 at 0 V. The device also exhibits good spectral selectivity and photoresponse characteristics in the UV range (280–370 nm). The peak responsivity (R) and specific detectivity (D*) of the CsCu2I3/Si heterojunction device are 7.1 mA/W and 2.6 × 1011 Jones at 0 V and 330 nm (~700 μW/cm2) light illumination, and shows good stability and reproducibility.
查看更多>>摘要：? 2022 Elsevier B.V.In Faraday supercapacitors, battery-type materials despite their high theoretical capacity have not shown prospect yet in application primarily due to their especially low cycling stability (< 10,000 cycles), sharp contrast to the carbon materials in electrical double layer capacitors (>> 100,000 cycles). The so far materials structure-stabilizing strategies, established on the acknowledged structure-destabilizing mechanism under electrochemical stress, seem not significantly effective or practical. Actually, the misunderstanding on structure-destabilizing mechanism leads to the slow progress of battery-type materials in application. In this work, the intrinsic structure-destabilizing mechanism is revealed as the agglomeration of materials originating from their dissolution-recrystallization behavior instead of from electrochemical stress. Based on the as-proposed mechanism, a rod-like micro-nano architecture with a thin carbonaceous shell is designed and built deliberately for Ni(OH)2 notorious in its especially low stability as a demonstration for stabilizing the structure of battery-type materials. The carbonaceous shell blocks the interflow of dissolved species between Ni(OH)2 rods, significantly reducing their agglomeration. This structure-stabilizing effect enables Ni(OH)2 ultra-long cycling life of > 100,000 cycles, thus verifying the as-proposed structure-destabilizing mechanism. The positive results in this work suggest that the significance of battery-type materials in supercapacitors should be revalued.
查看更多>>摘要：? 2022 Elsevier B.V.Premixed flame configuration is considered as an effective method for the synthesis of carbon materials. In this work, flexible single-walled carbon nanotube network decorated by carbon-encapsulated Fe2O3 nanoparticles (C@Fe2O3/SWCNT) membrane was in-situ fabricated via a facile floating catalyst premixed ethanol flame method, and followed by annealing treatment. In this process, low-cost ethanol and ferrocene were used as carbon source and catalyst precursor for the synthesis of C@Fe2O3/SWCNT, respectively. Benefiting from the interconnected conductive network, the as-fabricated C@Fe2O3/SWCNT membrane was used as a free-standing anode for lithium-ion batteries. Structural characterization revealed that the ultrafine Fe2O3 nanoparticles homogeneously anchored on the SWCNT network, which facilitates the fast diffusion for electron. Furthermore, the carbon layers uniformly enwrap on Fe2O3 can effectively suppress the aggregation and buffer the volume change of Fe2O3 during the lithiation/delithiation process. Consequently, this material delivered an excellent lithium storage performance with a high reversible capacity of 1294.7 mAh g?1 at 50 mA g?1, and an excellent cyclability of 82.5% retention is obtained after cycles at 2 A g?1. This study provides a novel low-cost and fast method for preparing flexible advanced electrode for next-generation rechargeable batteries.
查看更多>>摘要：? 2022 Elsevier B.V.The structural, magnetic and magnetocaloric properties of PrCo3?xCux intermetallic compounds were investigated in the composition range 0 ≤ x ≤ 0.6. X-ray diffraction investigations showed that all of the samples crystallize in the PuNi3-type crystal structure after annealing at 850 °C for 16 days. An anisotropic expansion of the unit cell along the c-axis occurs when the Cu concentration increases. Electronic structure calculations were performed, showing a good agreement with the experiments. The Curie temperatures decrease from 333 K for x = 0 to 170 K for x = 0.6, due to a weakening of the exchange interactions with the reduction of the effective number of magnetic nearest neighbors. All of the samples were found to be ferromagnetically ordered, the saturation magnetization at 4.2 K being inversely proportional to the Cu concentration value. The Co atomic moments decrease as the Cu content value increases due to the progressive filling of the Co 3d bands. Also, magnetic investigations at low temperatures suggest an enhancement of the magnetocrystalline anisotropy when Cu is added. A moderate magnetocaloric effect was found for all of the investigated samples. The maximum magnetic entropy change values, measured in an applied field ranging from 0 to 4 T, decrease from 1.39 J/kgK for x = 0 to 0.91 J/kgK for x = 0.6, while the RCP(ΔS)∕ΔB values are rather independent of Cu concentration.
查看更多>>摘要：? 2022 Elsevier B.V.Zn-Co sulfides with high energy density are promising materials for positive electrodes of supercapacitors. However, it is still imperative to develop a favorable architecture of Zn-Co sulfides to obtain a satisfying electrochemical response with improved electrons and ions transfer efficiency. Herein, for the first time, ZnCoS/C with the specific structure, numerous nanodendritics ZnCoS epitaxial growth along 3-D glucose-derived carbonaceous (C) scaffolds, is highlighted. The possible growth process and formation mechanism are carefully investigated. The functions of functional groups covalently bonding to C frameworks and deriving from PVP molecules are discussed to offer insights to guide the rational design of active and selective materials for electrochemical supercapacitors. We evaluate the electrochemical response of obtained ZnCoS/Cs. By varying the content of C of the reaction solutions, ZnCoS/C 20 synthesized with the addition of 20 mg C displays a maximum specific capacity of 682 C/g at 1 A/g, which is approximately 2 times greater than the bare ZnCoS electrode. The electrode ZnCoS/C 20 delivers outstanding rate capability (86% after increasing the current density 20 times) and reserves 89% of its initial specific capacity after 7000 charging/discharging cycles at 20 A/g. A hybrid supercapacitor was fabricated with ZnCoS/C 20 positive electrode and PrGO (porous reduced graphene oxide) negative electrode. The assembled supercapacitor displays an energy density of 40.6 W h kg?1 at a power density of 762 W kg?1 and a remarkable cycling performance of 72% after 6000 cycles. This work provides a promising strategy for the fabrication of metal sulfides-based hybrids for high-performance supercapacitors.
查看更多>>摘要：? 2022 Elsevier B.V.The influence of hydrogen on the structural evolutions of an Al-Mg-Si alloy during natural and artificial ageing was investigated experimentally. The aim of the study was a better understanding of interactions between hydrogen and crystalline defects and especially vacancies. Experimental data demonstrate that during natural ageing in hydrogen environment, the hardening response is delayed. This is attributed to a slower recovery of excess vacancies linked to a lower mobility. To confirm and quantify the influence of hydrogen on the vacancy migration energy, artificial ageing was carried out in conditions where the vacancy concentration is constant. Hence, long-time annealing treatments were carried out to investigate the influence of hydrogen on the coarsening of rod-shaped precipitates. Using transmission electron microscopy and atom probe tomography, it was demonstrated that the precipitate volume fraction and composition are unchanged under H2 atmosphere but the coarsening kinetic is significantly reduced. This leads to a delayed softening, in good agreement with theoretical estimates. Thus, even a low concentration of hydrogen in solid solution significantly affects the mobility of alloying elements in the aluminium matrix. This is the result of hydrogen-vacancy interactions that lead to an increase of the vacancy migration energy. Based on classical coarsening theories, it was possible to demonstrate that this increase is of about 5% for a concentration of hydrogen close to the vacancy concentration.
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