Aleksei S. KomlevDmitriy Y. KarpenkovRadel R. Gimaev
11页
查看更多>>摘要：FeRh alloys doped with the third element exhibit a change in the lattice and magnetic subsystems, which are manifested in antiferromagnetic- ferromagnetic (AFM-FM) first-order phase transition temperature, the shrinkage of the temperate hysteresis under transition, and the reduction of the saturation magnetization. All aforementioned parameters are crucial for practical applications. To control them it is quite important to determine the driving forces of the metamagnetic transition and its origins. In this manuscript ab initio calculations and experimental studies results are presented, which demonstrate the correlation between the structural and magnetic properties of the Fe_(50)Rh_(50-x)Pd_x alloys. The qualitative analysis of the metamagnetic phase transition driving forces in palladium-doped FeRh alloys was performed to determine their contribution to the evolution of magnetic and lattice subsystems. In addition, the impact of the impurities phases together with its magnetic behavior on the AFM-FM phase transition was considered.
查看更多>>摘要：Interfacing two-dimensional materials with three-dimensional world is never a subject that could be bypassed. In this work, MoS_2 nanoflakes were purposefully stacked to construct hollow tetrapod structure, which showed great development prospects as a powerful anode material in potassium-ion-battery realm. The accumulation of these tetrapods could build a grand macroscopic interconnected architecture with high porosity, which was propitious to penetration of electrolyte, accessibility of K~+ ions and reduction of K~+-ion diffusion distance. Moreover, it could provide adequate room for volume changes during potassiation/de-potassiation, and the lattice stress applied on one arm upon cycling could readily transfer to another arm, leading to high structural stability. More than that, the wedge-shaped arms securely anchored the carbon black, so as to make full contact between active material and conductive agent, and thus enhancing electrical conductivity of the whole anode. Furthermore, the hollow arms could also accelerate K~+-ion transport and cushion the volume variation to the greatest extent. This delicately-designed structure showed excellent cyclability, enhanced initial Coulombic efficiency and exceptional rate capability during electrochemical processes.
查看更多>>摘要：Herein, thin films of (Bi_2Se_3)_(1-x)(Bi_2Te_3)_x were synthesized by thermal evaporation in high vacuum using highly crystalline bulk samples of Bi_2Se_3 alloyed with Bi_2Te_3. Preparation and characterization together with probing the thermoelectric properties of thin (Bi_2Se_3)_(1-x)(Bi_2Te_3)_x films are discussed in this article. Crystal structure, surface morphology, roughness and lattice features of the deposited films were probed via XRD, SEM and HRTEM techniques, which confirmed the perfect crystallinity and the nano-scalability of the prepared thin films. Thermoelectric measurements were carried out for the as-deposited films within a temperature range of 300-473 K. Seebeck coefficient of the studied samples is about two times larger than that of the previously reported bulk samples. The highest power factor was recorded at 131 μW/m K~2 at 473 K. The high value of the power factor shows that the materials under the study are promising for applications such as resource recovery of waste and also as nanomaterials for environmental applications. Very low electronic thermal conductivity was obtained due to the small electrical conductivity and due to the scattering of carriers by the tiny grains constituting the prepared films.
查看更多>>摘要：Multi-principal-element alloys (MPEAs) are a wide class of materials currently at the center of numerous investigations. Key-issues with MPEAs are related with controlling the onset of (i) long-range order and (ii) phase separation, both processes being in general detrimental to the properties. While trends (i) and (ii) are strongly dependent on the precise proportions of metallic elements around the reference equiatomic MPEA, the tremendously large composition space makes it a tricky task to heuristically identify optimized MPEAs. In practice, this often leads to undesired second-phase ordered particles. This deficiency emphasizes the relevance of modelling and simulation tools designed to facilitate the exploration of MPEA composition spaces. In this atomic-scale work, we propose a "composition-constrained" point mean-field formalism resting on alloy pair energetics, to investigate trends (i) and (ii). This formalism is currently applicable to a wide panel of such systems built from ~ 30 chemical elements. Its application to several MPEAs along the AlCoCrFeNi → AlCrFeMnNi→ AlCrFeMnMo sequence evidences striking differences between these systems, and demonstrates its efficiency to get at-a-glance information about (i) and (ii) features for various MPEAs. The flexibility of the proposed simulation approach makes it easily employable in conjunction with experiments on well-equilibrated MPEA samples, for thermodynamic characterizations of MPEAs.
查看更多>>摘要：Direct dual Z-scheme heterostructured nanocomposite TiO_2-WO_3-CeO_2 (NC) and pristine metal oxides na-nostructures (NSs) were fabricated using a facile co-precipitation route. XRD, FTIR, and Raman data have confirmed the formation of NSs and NC. FESEM images showed quasi-mesoporous morphology of as-grown nanocomposite. EDX analysis confirmed the existence of titanium (Ti), cerium (Ce), and tungsten (W) in grown NC. The energy bandgap of NC was narrow 2.45 eV as compared to NSs. The higher electrical conductivity and lower recombination rate of NC were observed in IV and PL analysis. The photodegradation efficiency of NC was recorded 99.8% after 60 min under sunlight radiation against methylene blue (MB), which was significantly higher than NSs. NC catalyst has shown excellent photodegradation against other organic pollutants and has superior recyclability up to 7th cycle toward MB dye with a ~ 6% deficit in photodegradation efficiency. The antimicrobial activity results indicated the higher inhibition ability of NC against E. coli, K. pneumoniae, S. aureus, P. Vulgaris, and P. aeruginosa with maximum inhibition zone diameter 25, 29, 26, 28, and 27 mm, respectively. The electrochemical tests including CV, EIS, and GCD exhibited the superior capacitive behaviour of NC. These results demonstrate that grown NC is an efficient material for electrochemical devices, water purification, and biomedical applications.
查看更多>>摘要：There is an imperative need for a single photodetector that can be used to detect the entire electromagnetic spectrum from the ultraviolet (UV) to the near-infrared (NIR). Such a device can reduce the cost and surface area required for device integration. In addition to broadband photodetection, optical transparency must be considered as another critical parameter. Poor transparency or opacity renders their use a deprecated choice in transparent electronics. In this paper, a completely transparent, electrode-free n-n heterojunction (n-ZnO/n-V_2O_5) photodetector is developed for high responsivity and microsecond responses. This is the least-studied type of heterojunction. It is a Schottky junction and can provide rapid device performance due to its unipolar carrier transport. The wide bandgap of ZnO and the narrow bandgap of V_2O_5 make this heterojunction a transparent broadband photodetector. The n-ZnO/n-V_2O_5 photodetector offers > 50% optical transmittance in the Vis-NIR region, with remarkably high photoresponsivities of 18.86 A/W, 6.10 A/W, and 4.40 A/W in the UV, Vis, and NIR regions, respectively. The device also offers high detectivity, high external quantum efficiency, and fast rise and fall times of 230 and 340 us, respectively. Briefly, this work provides a path towards the development of transparent, electrode-free broadband photodetectors for next-generation transparent electronics.
查看更多>>摘要：Constructing core-shell heterostructures can effectively improve the hindered issues such as decreased sensitivity and poor selectivity from the chemoresistive gas sensors in the complex atmosphere. Herein, an effective hydrothermal-water bath treatment combined strategy was designed to obtain the unique ethanol adsorption preferred ZnIn_2S_4 sheet shell/In_2O_3 sphere core (ZnIn_2S_4 @In_2O_3) nanosphere (NS) heterostructures. Particularly, according to the characterization and gas sensing test results, the chemoresistive sensor of ZnIn_2S_4 @In_2O_3 NS-2 with the highest chemisorbed oxygen concentration shows satisfactory selectivity to ethanol vapor, and the response is the highest (54) compared to other composite controls, which is almost 4-fold of that of the pure In_2O_3 NS reference. Besides, the relatively lower working temperature (220 °C), low limit of detection (LOD, 30 ppb) and long-term stability were also obtained. The enhanced performance of the core-shell ZnIn_2S_4 @In_2O_3 NS-2 based sensor may be due to the synergistic effect between ZnIn_2S_4 sheets and In_2O_3 sphere moieties. Meanwhile, the large specific surface area from the outer shell of ZnIn_2S_4 sheets is also another contribution factor, which supplies the most chemisorbed oxygen sites and transportation channels to promote the interfacial gas diffusion, catalytic oxidation and product desorption.
查看更多>>摘要：A series of Dy~(3+) activated Ba(YLu)_2Si_3010 samples were prepared by high temperature solid-phase method. The purity of the phase was determined and the structural changes were analyzed. Under excitation at 350 nm, the BaY_2Si_3O_(_10): Dy~(3+) phosphor shows two stronger luminescence peaks at 486 nm and 572 nm and weaker emission peak at 668 nm. In addition, with the continuous replacement of Y~(3+) in the matrix by Lu~(3+) ions, the chromaticity coordinates of samples in the system can be adjusted from the cold white region to the warm white region, and the luminescence performance of phosphors can be effectively improved. It was observed that the thermal stability of the phosphor was gradually enhanced with Lu~(3+) concentration increases, and the emission intensity of the BaLu_2Si_3O_(10): 0.04Dy~(3+) phosphor at 453 K could still maintain 83.78% of that at room temperature, which was discussed in conjunction with the Debye temperature and the rigid structure model to provide a reference for the improvement of the thermal stability performance. In addition, the increase of the concentration of Lu~(3+) ions doping will shorten the lifetime of phosphors due to the non-radiative energy transfer caused by the shortening of the ion distance in the lattice.
查看更多>>摘要：Poor dispersion of nanodiamonds (NDs) is the bottleneck to exploit their intrinsically excellent properties in metal matrix composites (MMCs). In this study, a strategy of surface modification was developed to uniformly disperse ND particles into 2024 aluminum alloy. Microstructure observations showed that individual NDs are closely contacted with the matrix, forming reaction-free interfaces. Consequently, a high-strength 0.8 vol% ND/2024A1 composite with an ultimate tensile strength of 741.0 MPa is developed. Theoretical and experimental measurements prove that the strength improvement of ND/2024A1 composite is mainly attributed to the Orowan strengthening, thermal mismatch strengthening and grain refinement strengthening. This work demonstrates the effective application of NDs as a reinforcement for MMCs towards high-specific-strength materials.
查看更多>>摘要：Electron backscatter diffraction (EBSD) was applied to investigate the superplastic behavior of a fine-grain Al-Mg-Li alloy. It was found that microstructural changes were noticeably influenced by the occurrence of continuous dynamic recrystallization. This mechanism involved a transverse subdivision of pre-elongated grains which eventually transformed into chains of nearly-equiaxed grains. A body of experimental observations, including extensive strain hardening, marked grain elongation, the formation of pronounced substructure in interior regions of grains, and the development of crystallographic texture, provided strong evidence of large amounts of intragranular slip operating during superplastic flow.
NSTL
Elsevier