查看更多>>摘要：? 2022 Elsevier B.V.We developed heterojunction electron-transfer layers (ETLs) comprising layers of metal oxides and phenyl-C71-butyric acid methyl ester (PCBM) for use in glass/indium tin oxide/hole transport layer/Perovskite/ETL/LiF/Al solar cells and X-ray detectors. Indium gallium zinc oxide (IGZO), tin oxide (SnO2), or IGZO/SnO2 layers were stacked on a PCBM layer via radio frequency (RF) magnetron sputtering at various temperatures. The formation of the metal-oxide layers and on a PCBM film were confirmed by conducting compositional and elemental mapping studies. Current-voltage experimental results show that the heterojunction fabricated by forming a IGZO/SnO2 layer on a PCBM film possessed higher charge carrier capacity and exciton dissociation properties compared with using either IGZO or SnO2 separately. The Perovskite solar cell with an IGZO/SnO2@100/PCBM (100 refers 100oC of RF sputtering temperature) ETL attained a power conversion efficiency (PCE) of 12.56 ± 0.15%, which was 36% more efficient than a device with a pure PCBM ETL (PCE = 9.22 ± 0.09%). Moreover, an X-ray detector fabricated with an IGZO/SnO2@100/PCBM ETL obtained a maximum sensitivity of 3.98 mA/Gy·cm2 and collected charge density (CCD)-dark current density (DCD) of 13.29 μA/cm2.
查看更多>>摘要：? 2022 Elsevier B.V.Although deformation twinning has been demonstrated to improve the strain hardening and ductility of metals and alloys with low stacking fault energies (SFEs), the optimum grain size for maximum strength-ductility combination still needs to explore. In this work, we selected Cu- 30 wt% Zn alloy with extremely low SFE (7 mJm-2) acting as a model material. Specifically, Cu- 30 wt% Zn samples with different grain sizes ranging from 628 nm to 30.6 μm were prepared by equal-channel-angular pressing (ECAP) and subsequent annealing. Tensile test revealed that the maximum strength-ductility combination (ultimate tensile strength of 565 MPa and ductility of 20%) corresponds to a mean grain size of 3.8 μm. Electron backscatter diffraction (EBSD) indicated that pre-existing annealing twins in fine-grained Cu- 30 wt% Zn alloy annihilated at the initial deformation stage (<10% tensile strain) via detwinning of thin twin lamellae (<1 μm) and conversion of twin boundaries of thick twin lamellae (>1 μm) into conventional high-angle grain boundaries. In the later stage of deformation (>10% strain), deformation twinning occurred in grains with<111>orientation parallel to tensile direction, suggesting the combination of both detwinning and twinning deformations caused the maximum strength and ductility synergy. Our findings provide insights into optimization of strength and ductility of metals with low SFEs and detwinning-twinning deformation mechanisms.
查看更多>>摘要：? 2022 Elsevier B.V.In this paper, the Mg-9Gd-4Y–2Zn-0.5Zr (wt%) alloy after one pass of upsetting and extrusion was subjected to the rotating shear extrusion (RSE) method and backward extrusion (BE) method at 420 °C. Compared with the BE method, torsion deformation and shear deformation were synthetically introduced to the RSE process. The RSE technique had the advantages of a low forming load, large strain and more sufficient deformation. The results demonstrated that the RSE method had more advantages than the BE method in terms of grain refinement and mechanical performance improvement. The average grain size of the RSEed alloy was refined from ~22 μm of the original alloy to ~8.5 μm. In addition, the proportion of dynamic recrystallization (DRX) increased from ~56% of the original alloy to ~83% via the RSE process. The degree of fragmentation of the lamellar and block-shaped LPSO phases in the RSEed alloy was more intensive than that of the BEed alloy, and the particle phase distribution among the crystal grains was more uniform. The RSEed alloy presented a single texture and a strong [2?1?10] orientation component and effectively weakened the texture intensity. The ultimate tensile strength (UTS), tensile yield strength (TYS) and elongation (EL) of the RSEed sample were 350 MPa, 258 MPa and 17%, respectively. Compared with the BEed sample, the mechanical properties of 325 MPa (UTS), 240 MPa (TYS) and 12% (EL) had higher strength and toughness. After the same T5 (200 ℃/90 h) heat treatment, the mechanical properties of the RSEed sample could reach 420 MPa (UTS), 280 MPa (TYS) and 13% (EL), while BEed sample were 371 MPa (UTS), 273 MPa (TYS) and 10% (EL). Additionally, compared with the BEed alloy, the mechanical properties of the RSEed alloy are better due to finer grains, broken LPSO phases, dispersed particle phases and texture modification.
查看更多>>摘要：? 2022 Elsevier B.V.Understanding the magnetization reversal mechanism of a core-shell structure grains formed in the grain boundary diffused Nd-Fe-B magnet can further improve the utilization efficiency of heavy rare earth resources to more effectively improve the coercivity of Nd-Fe-B sintered permanent magnet. In this paper, magnetic domain structure and its dynamic evolution of core-shell structural grains in grain-boundary-diffused Nd-Fe-B magnet were in-situ observed. Wider domains are found in shell regions due to higher anisotropy constant and lower saturation magnetization. The domain motion revealed that the demagnetization process of core-shell structure has a multi-step nucleation process. The nucleation of the core-shell structural grain firstly occurs at the core regions, while another reverse nucleation appears at the outmost portion in shell-region at a larger reverse field. The micromagnetic simulation results confirm the possibility of the nucleation and reversal process observed in the experiment. Our results can help understanding the demagnetization process and the coercivity enhancement mechanism of grain-boundary-diffused Nd-Fe-B sintered magnet.
查看更多>>摘要：? 2022 Elsevier B.V.To improve the electrochemical performance of thin films based on Zn0.4Ni0.6O (ZNO) solid solution compound (SSC), Li-decorated ZNO [(Zn0.4Ni0.6)0.95Li0.05O, ZNLO] SSC was designed in this work. ZNO and ZNLO nanostructured thin films were prepared by RF magnetron sputtering with related lab-made ceramic targets. Phase composition, element valences, microstructure, electrochemical properties and electrochemically-induced phase evolution of the thin films were investigated. The cells assembled with ZNLO thin films as electrode deliver high reversible specific capacity of 773 mAh g?1 at 200 mA g?1 after 200 cycles, which is extremely superior to that of the ZNO thin film (363 mAh g?1). ZNLO thin film shows a high rate performance with specific capacity of 511 mAh g?1 at 1000 mA g?1 even after 750 cycles. The electrochemically induced phase evolution was studied by transmission electron microscopy, and the results revealed that nearly complete redox conversions of Zn-Ni-O ? Ni/Zn and ZnO ? Zn took place in ZNLO thin films electrode. The high electrochemical performance owes to the enhanced electrical conductivity of thin film doped with Li-ion and nanostructured characteristics of thin film that provide high specific surface and redox conversion processes.
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