查看更多>>摘要：? 2022 Elsevier B.V.W-doped In2O3 (IWO) films prepared by reactive plasma deposition (RPD) technique at 150 °C have been studied to replace Sn-doped In2O3 (ITO) serving as transparent electrodes for p-i-n structured perovskite solar cells. The optical and electrical properties of IWO films were found to depend on the oxygen partial pressure of deposition process. Compared with the reference ITO films, the IWO films obtained at an oxygen partial pressure of 0.12 Pa exhibited prominent performance, including higher near-infrared transmittance and carrier mobility. Furthermore, the IWO films showed higher work function than that of the ITO films, resulting in the enhancement of open-circuit voltage (0.982 V vs 0.901 V) and conversion efficiency (12.9 % vs 11.9 %). It can be attributed to that high work function of the IWO films reduced the carrier transport barrier at the interface between transparent electrode and PEDOT:PSS and enhanced the carrier collection near the edge of the perovskite bandgap. The excellent properties of the RPD-prepared IWO films indicate that it is a promising transparent electrode material for p-i-n structured perovskite solar cells, especially for applications requiring low-temperature fabrication.
查看更多>>摘要：? 2022 Elsevier B.V.The effective surface-to-volume ratio and adsorption property of quantum dots have recently been explored as prospective building blocks for the development of high-performance gas sensors. In this work, we report colloid quantum dots of lead sulfide (PbS) synthesized via the hot injection method and employed as a room temperature real-time O3 sensor. The crystallite size of high-quality PbS QDs has been analyzed by XRD and TEM images and found very low i.e. about 3–4 nm. The thin film of PbS was used to sense the trace ozone with and without visual light irradiation. The results show that the PbS QDs can easily absorb and desorb ozone molecules at room temperature. The different wavelength lights (blue, green, and red light) can not affect the response or sensitivity, response and recovery time. The responses are about 1.5, 1.9, 1.93, 1.86 and 2.4 under red (650 nm), green (550 nm), orange (600 nm), blue (450 nm) LED and fluorescent lamps (450–650) (on the ceiling 3 m-high), respectively. The results are due to dynamics sensing, in which visual light simultaneously increases the absorption and desorption of ozone molecules. We also find that the sensing response is the largest under fluorescent lamp irradiation. The limit of detection has been calculated by linear fitting of sensor response and found to be 1.34 ppb. From differential change w.r.t. time, it has been observed that PbS QDs and O3 monitor detection rate is almost the same and the response time ratio of PbS QDs with optical sensor decreases from 3.1 to 1.18 by using fluorescent light. According to the above results, PbS QDs gas sensor has a good performance for ozone at room temperature.
查看更多>>摘要：? 2022 Elsevier B.V.The metadynamic recrystallization (MDRX) characteristics of a Ni-Cr-Mo alloy are investigated using the double-pass thermal compression tests. The impacts of double-pass compression parameters on the kinetic features and microstructural changes are clarified. Results signify that the MDRX softening behaviors are remarkably accelerated with increasing of compression temperature, first-pass strain or strain rate. The bulging of the MDRX grain boundary and the annihilation/interaction of substructures become weaken at low compression temperature or small first-pass strain, enhancing the grain refining during MDRX. However, the MDRX grains coarsen rapidly with decrease of strain rate. Based on the comprehensive impact of double-pass compression parameters on softening fraction and grain size, the MDRX kinetic model and MDRX grain size model are developed. The predicted results are well matched the experimental data, which suggests that the established models can precisely characterize the changes of softening characteristics and grain size of the researched alloy during MDRX.
查看更多>>摘要：? 2022 Elsevier B.V.In order to develop efficient combustion catalysts for solid propellants, three intermetallic compounds of Sn-Cu, Sn-Co and Sn-Ni were synthesized by a hydrothermal method and their effects on the thermal decomposition and ignition properties of 1,3,5-trinitroperhy-dro-1,3,5-triazine (RDX) and 5,5′-bistetrazole-1,1′-diolate (TKX-50) were studied systemically. The results show that Sn-Cu, Sn-Co and Sn-Ni can all promote the thermal decomposition of RDX, which reduce the exothermic decomposition peak temperature of RDX by 3.2, 1.9 and 4.8 ℃, respectively. And the apparent activation energy of RDX was reduced by 82.1 kJ·mol?1 after adding the Sn-Ni intermetallic compound. In comparison with RDX, the exothermic peak temperature of TKX-50 was reduced more significantly, which was decreased by 11.9, 1.5 and 6.6 ℃ in the existence of Sn-Cu, Sn-Co and Sn-Ni, respectively. Additionally, Sn-containing intermetallic compound could reduce the ignition delay time of RDX under high power laser density, while the ignition delay time of TKX-50 could be decreased in the full power density range of the experiment. Besides, the flame combustion intensity and propagation rate of RDX and TKX-50 were significantly heightened by adding the three compounds. The comparison of pyrolysis and ignition performance before and after adding Sn-containing intermetallic compound into RDX and TKX-50 shows that Sn-containing intermetallic compound has great application prospects for improving the heat release and combustion characteristic of solid propellants.
查看更多>>摘要：? 2022 Elsevier B.V.LiAlH4 is considered as a promising material for solid state hydrogen storage. However, the lack of reversibility along with sluggish kinetics hinders its practical application. In this paper, hollow carbon nanospheres (HCNs) were used as a porous scaffold to confine LiAlH4 via solvent impregnation method. Nanoconfined LiAlH4 (LiAlH4@HCNs) exhibited significant improvements in hydrogen sorption compared to its bulk counterpart. LiAlH4@HCNs releases hydrogen sharply at 146 °C with full conversion to LiH within 1.5 h. The desorbed material can also be regenerated back to some extent into LiAlH4 under 8 MPa H2 at 150 °C. Measurement of the pressure-composition isotherm suggests an alteration in the equilibrium state upon confinement of LiAlH4 in voids of a few nanometres and thus altered hydrogen thermodynamic paths.
查看更多>>摘要：? 2022 Elsevier B.V.To determine the influence of Re and Ru on the phase morphologies and microstructure in Ni-based superalloys, a series of model alloys derived from the 4th generation TMS-138 superalloy have been investigated with systemically changing Re and Ru additions. All alloys are subjected to solid solution and aging treatments to achieve the typical γ/γ′ two phases microstructure. Phase transition temperatures are measured by using differential scanning calorimetry. The Re is found to increase the γ′-solvus temperature with a slope of roughly 5.4 ℃ per wt% Re in Ru-free alloys and 2.3 ℃ per wt% Re in 2Ru alloys, while the Ru exhibits much weaker effect. Microstructure and composition of the two phases are examined to understand the Re and Ru effects on γ′ size, shape, volume fraction, the elemental partition behavior, and the γ/γ′ lattice misfit. The results show that the addition of Re affects size and shape of γ′ precipitates, and also reduces γ/γ′ lattice misfit significantly. Meanwhile, Re increases partition coefficients of Cr and Ru. In comparison, the addition of Ru seems to have little effect on morphology of γ′ precipitates and the γ/γ′ lattice misfit, but Ru appears to alter partitioning behaviors of other elements. Because Re and Ru are two key elements for high generation Ni-based single crystal (SX) superalloys, this work might provide guidelines for designing next generation of SX superalloys.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, Cu-0.8Cr-0.1Zr alloy was prepared by vacuum horizontal continuous casting method. The effect of different thermo-mechanical treatment processes on the properties was studied, and the microstructure evolution at different stages of thermo-mechanical treatment were observed by SEM, EBSD and (HR)TEM. The results showed that the optimal comprehensive performance of tensile strength (803 MPa) and conductivity (76% IACS) was obtained by three-stage drawing and thermal treatment (primary 43.75% drawing and solution treatment at 950 °C for 60 min + secondary 97.2% drawing and aging at 500 °C for 30 min + tertiary 75% drawing). Through the microstructure characterization, it was found that the morphology and distribution of the Cr-rich primary phase can be regulated by solution treatment, and inherited during the thermo-mechanical treatment. It acts as a nucleation point and hard point, thereby refining the grain and improving the strength of the alloy. Additionally, it reduces the number of solid solution atoms in the matrix and prevents the loss of conductivity. Furthermore, drawing with a large amount of deformation can produce a nano-lamellar structure with high temperature stability, and drawing after high temperature aging can induce substructure formation. The combination of nano-lamellar structure and substructure further improves the strength.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, AlSiMgMnCu alloys with different Cu and Mg contents were fabricated by high vacuum die casting (HVDC) technique. The phase formation and their microstructure evolution are quantitatively studied by serial block-face scanning electron microscopy (SBFSEM) at nano-scale in three-dimensions. Through analyzing their three-dimensional (3D) microstructure, effects of the spatial distribution, volume fractions and morphology of the intermetallic phases on the alloy's mechanical properties are comprehensively discussed. It is found that, with higher Cu content and lower Mg content, the nucleation and growth of θ-Al2Cu phase would have advantage over Q-Al5Cu2Mg8Si6 phase. In contrast, decreasing Cu/Mg ratio by increasing Mg content is in favor of the nucleation and growth of the Q-Al5Cu2Mg8Si6 phase. The uniformly distributed fine θ-Al2Cu phase provides the highest contribution to the strengthening of the HVDC AlSiMgMnCu alloys. For the Cu/Mg ratio to be 3, an as-cast HVDC Al-10Si-0.2Mg-0.5Mn-0.6Cu alloy with optimized ultimate tensile strength, yield strength and elongation of 330 MPa, 162 MPa and 10.2%, respectively, had been produced.
查看更多>>摘要：? 2022 Elsevier B.V.There is a hindrance in modeling Gibbs energies of high melting alloys via the CALPHAD approach because of the scarcity of experimental results. All the conventional methods suffer to overcome the practical difficulties at high temperatures. Despite these setbacks, this paper provides a reliable way of using an arc-melting device in conjunction with a pyrometer to measure high-temperature phase transitions and developing a hybrid approach to construct a Ni-Si-Zr phase diagram. First, the preparation of Ni-Si-Zr alloy is via arc-melting technique. Forty-two as-cast sample analyses provide the primary solidifying phase encompassing the Ni-Si-Zr composition domain. Heat-treatment of fifteen samples at 1073 K refines the isothermal section, emphasizing the Zr-rich corner. Ni-Si-Zr alloy's temperature recording using pyrometer in the arc-melting device while cooling after melting reveals novel Ni-Si-Zr's invariant reactions. The time versus temperature graph comparison with its as-cast electron micrograph reveals several phase transitions. The notable research output of this research work is the hybrid approach, including the experiments circumventing hurdles at high temperatures and the first-principles method to calculate the intermetallic phase's formation energy. The hybrid approach in the present work has established a phase diagram and the thermodynamic description over the extensive temperature and composition ranges for a highly complicated ternary system. The presently developed hybrid methodology is also applicable to construct a phase diagram for other complex ternary systems up to ≈ 3700 K.
查看更多>>摘要：? 2022 Elsevier B.V.Perovskite LaCoO3 has unique mixed ionic electronic and structural defects, which has high research value in microwave absorption field. LaCoO3 precursor was prepared by sol-gel method, and LaCo1?xFexO3 (Fe-LCO, x = 0, 0.05, 0.1 and 0.15) with rhombic symmetric structure was successfully synthesized at 600 °C. By refinement of X-ray diffraction (XRD) (Rietveld analysis), it was found that Fe doping makes LaCoO3 lattice constant and cell volume increase. As a dielectric loss microwave absorbing material, the electromagnetic attenuation of LaCoO3 is mainly due to the conduction loss, while the interface and dipole polarization are secondary reasons. It finds that Fe doping can improve the wave absorption performance of LaCoO3. The best absorbing performance was obtained when Fe content is x = 0.1, with the maximum reflection loss of ? 38.99 dB at 10.8 GHz and the effective absorption bandwidth (RL<?10 dB) is 4.48 GHz, while the corresponding thickness was only 3 mm. In summary, LaCoO3 has broad application prospects in X and Ku bands.
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