| 1. |
- Liu, Junwei, et al.
(författare)
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Polymer synergy for efficient hole transport in solar cells and photodetectors
- 2023
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Ingår i: Energy & Environmental Science. - : ROYAL SOC CHEMISTRY. - 1754-5692 .- 1754-5706.
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Tidskriftsartikel (refereegranskat)abstract
- Hole transport materials (HTMs) have greatly advanced the progress of solution-based electronic devices in the past few years. Nevertheless, most devices employing dopant-free organic HTMs can only deliver inferior performance. In this work, we introduced a novel "polymer synergy" strategy to develop versatile dopant-free polymer HTMs for quantum dot/perovskite solar cells and photodetectors. With this synergy strategy, the optical, electrical and aggregation properties of polymer HTMs can be modulated, resulting in complementary absorption, high hole mobility, favorable energy landscape and moderate aggregation. Moreover, a clear orientational transition was observed for the developed HTMs with a 9-fold increase in the face-on/edge-on ratio, providing a highway-like carrier transport for electronic devices, as revealed by in situ characterization and ultrafast transient absorption. With these benefits, the photovoltaic and photodetection performance of quantum dot devices were boosted from 11.8% to 13.5% and from 2.95 x 10(12) to 3.41 x 10(13) Jones (over a 10-fold increase), respectively. Furthermore, the developed polymer HTMs can also significantly enhance the photovoltaic and photodetection performance of perovskite devices from 15.1% to 22.7% and from 2.7 x 10(12) to 2.17 x 10(13)Jones with the same device structure, indicating their great application potential in the emerging optoelectronics.
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| 2. |
- Jiang, Dong-yi, et al.
(författare)
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Surface water quality and potential health risk assessments in Changsha-Zhuzhou-Xiangtan section of Xiangjiang River, China
- 2019
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Ingår i: journal of central south university. - : Springer Science and Business Media LLC. - 2095-2899 .- 2227-5223. ; 26:12, s. 3252-3260
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Tidskriftsartikel (refereegranskat)abstract
- The Changsha-Xiangtan-Zhuzhou City Group is a heavy industrial district and accepted as the serious pollution area in the Xiangjiang River basin. In this study, 7 metals (Pb, Hg, Cd, As, Zn, Cu and Se) and the river water quality parameters including pH, dissolved oxygen (DO), Escherichia coli (E. coli), potassium permanganate index (CODMn), dichromate oxidizability (CODCr), five-day biochemical oxygen demand (BOD5), ammonia nitrogen (NH4+-N), total nitrogen (TN), total phosphorus (TP) and fluoride (F-) in 18 sampling sites of the Changsha-Xiangtan-Zhuzhou section are monthly monitored in 2016, which is the year to step into the second stage of the Xiangjiang River Heavy Metal Pollution Control Implementation Plan. It is found that E. coli, TN and TP are the main pollutants in the Changsha-Zhuzhou-Xiangtan section, and the pollution of heavy metal is not serious but As with potential risk to local people especially children should be concerned. In addition, Xiangtan city is mainly featured with heavy metal pollution, while Zhuzhou and Changsha city are both featured with other pollutants from municipal domestic sewage.
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| 3. |
- Huo, Xiaole, et al.
(författare)
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Effect of ultrasonic vibration on static properties of 5A06 aluminum alloy self-piercing riveting joints
- 2023
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Ingår i: Cailiao Kexue yu Gongyi/Material Science and Technology. - : Harbin Institute of Technology. - 1005-0299. ; 31:2, s. 44-49
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Tidskriftsartikel (refereegranskat)abstract
- Self-piercing riveting process is a new connection technology with excellent performance, green, and high efficiency. It can realize the connection of the similar, different, and multi-layer light alloy sheet materials and is widely used in new energy vehicles and other fields. Furthermore, it is becoming one of the critical technologies for achieving a lightweight body. However, because the self-piercing riveting joint is a typical tight connection component, fretting damage is prone to occur under the action of alternating stress or vibration, resulting in premature joint fatigue failure. This paper uses 5A06 aluminum alloy sheet material to carry out self-piercing riveting and ultrasonic self-piercing riveting composite connection tests under different ultrasonic welding tool heads. Based on the tensile-shear and electron microscope tests, the effect of ultrasonic vibration on the static properties of 5A06 aluminum alloy self-piercing riveted joints was studied. The results show that: ultrasonic vibration can effectively improve the static properties of self-piercing riveted joints; the ultrasonic metal welding will form a solid phase of welding between the sheets during the composite self-piercing riveting, which is the fundamental reason for improving the mechanical properties of the combined joint; the area of ultrasonic metal welding joints affects the mechanical properties of self-piercing riveted joints; the degree of ultrasonic solid-phase welding is higher when the welding area is more extensive; ultrasonic welding will increase the temperature of the rivet, which will affect the stability of the joints to a certain extent. © 2023 Harbin Institute of Technology. All rights reserved.
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| 4. |
- Long, Doudou, et al.
(författare)
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Improving texture and microstructure homogeneity in high-purity ta sheets by warm cross rolling and annealing
- 2021
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Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of texture and microstructure uniformity in high-purity tantalum (Ta) sheets during 135◦ warm cross rolling (WCR) was analyzed in detail. X-ray diffraction suggested that relatively uniform ‘ideal’ deformation texture distribution across the thickness could be obtained from WCR, since more potential slip systems could be activated. Electron backscatter diffraction (EBSD) results indicated that the change in strain path in warm rolling could enhance dislocations mobility and increase the probability of dislocations rearrangement and annihilation. Thus, the proportion of low-angle grain boundaries was significantly reduced, and more sub-grain boundaries or sub-grains were formed via WCR. The calculation of geometrically necessary dislocation density based on the strain gradient model supports this result. The analysis of relative Schmid factor combined with the strain contouring map indicated that inhomogeneous orientation-dependent grain subdivision could be effectively weakened, and relatively uniform strain distribution could be formed in the WCR sample. Upon annealing, uniform fine grain size and more randomly oriented grains were obtained in the WCR sample after the completion of recrystallization because of relatively uniform grain subdivision and stored energy distribution.
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| 5. |
- Niu, Li-Ping, et al.
(författare)
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Mechanism of fluidized chlorination reaction of Kenya natural rutile ore
- 2014
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Ingår i: Rare Metals. - : Springer Science and Business Media LLC. - 1001-0521 .- 1867-7185. ; 33:4, s. 485-492
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the thermodynamics and kinetics of nature rutile carbochlorination in a fluidized-bed were investigated. The thermodynamic calculations of TiO2-C-Cl-2 system show that when C is excess in the solid phase, titanium tetrachloride and carbon monoxide can exist stably. At high temperature, the reaction with CO as the product is the dominant reaction. The appropriate reaction conditions are as follows: reaction temperature of 950 A degrees C, reaction time of 40 min, carbon ratio of 30 wt% of rutile, natural rutile particle size of -96 mu m, petroleum coke size of -150 mu m, and chlorine flow of 0.036 m(3)center dot h(-1). Under the above conditions, the reaction conversion rate of TiO2 can reach about 95 %. This paper proposed a reaction rate model, and got a rutile chlorination rate formula, which is generally consistent with the experimental data. For the TiO2-C-Cl-2 system, the reaction rate is dependent on the initial radius of rutile particle, density, and the partial pressures of Cl-2. From 900 to 1,000 A degrees C, the apparent activation energy is 10.569 kJ center dot mol(-1), and the mass diffusion is found to be the main reaction-controlling step. The expression for the chlorine reaction rate in the C-Cl-2 system is obtained, and it depends on the degree of reaction, the partial pressure of Cl-2, and the size of rutile particle.
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| 6. |
- Qian, Xukun, et al.
(författare)
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Structure stability of metal-organic framework MIL-53 (Al) in aqueous solutions
- 2013
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 38:36, s. 16710-16715
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Tidskriftsartikel (refereegranskat)abstract
- The structural stability of MIL-53 (Al) in different pH aqueous solutions from room temperature to 100 degrees C has been investigated. Experimental results show MIL-53 (Al) is stable and highly resistant to hydrolysis in neutral and acidic solutions. It can retain its crystallinity and permanent porosity without structural collapse. The good structure stability of MIL-53 (Al) to aqueous solutions is quite unusual among the MOFs. The nitrogen adsorption for the soaked frameworks show a typical type I isotherm. In basic aqueous solution, MIL-53 (Al) undergoes structure transformation.
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| 7. |
- Zhu, Jialin, et al.
(författare)
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Enhancing the {100} grain subdivision in high-purity tantalum sheets by asymmetric cross rolling
- 2020
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Ingår i: Materials Characterization. - : Elsevier BV. - 1044-5803. ; 166
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Tidskriftsartikel (refereegranskat)abstract
- Weak subdivision or fragmentation ability of deformed {100} (<100> // ND, normal direction) grains by traditional unidirectional (symmetric) rolling results in uneven deformation during tantalum (Ta) processing. Thus, a recently developed asymmetric cross rolling (ACR) is adopted in this work to enhance the subdivision of {100} grain in Ta sheets. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and Vickers hardness (HV) were used for the characterisation of microstructure in deformed {100} grains. It is shown that added shear strain component in the ACR leads to heterogeneous deformation substructures within {100} grains. The increase of speed ratio in ACR further enhances the subdivision of deformed {100} grains and thus increases the density of geometrically necessary dislocations (GNDs) in them. The computation of the largest Schmid factor (SFrolling) along with Taylor model suggests that the ACR promotes easier slip within deformed {100} grains. Therefore, the necessary total shear strain contributing to the increase of GNDs density is small. By contrast, the shear strain accumulated after CR-1.0 is distributed more evenly in each slip system resulting in rather sparse distribution of dislocation lines.
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| 8. |
- Zhu, Jialin, et al.
(författare)
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The evolution of texture and microstructure uniformity in tantalum sheets during asymmetric cross rolling
- 2020
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Ingår i: Materials Characterization. - : Elsevier BV. - 1044-5803. ; 168
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of texture and microstructure uniformity in tantalum (Ta) sheets for sputtering target applications is analyzed in detail across the thickness during asymmetric cross rolling (ACR). Three samples with different strains, i.e. 60%, 70% and 80% are obtained via ACR processing. X-ray diffraction suggests that the increase of strain during ACR results in the randomization of deformation texture across the sample thickness due to the penetration of shear strain into the center. Electron backscatter diffraction results indicate that the increasing strain in ACR can alleviate region-dependent microstructure inhomogeneity. This is also confirmed by the distributions of Vickers hardness and geometrically necessary dislocations. Taylor model analysis along with strain contouring maps suggest that relatively low and centralized number of active slip systems in the 80% sample effectively reduces strain concentrations and thus homogenizes the average shear strain of most active slip system in different grain orientations. Upon annealing, nuclei with random orientations can grow evenly from the deformed matrix in the 80% sample because of relatively homogeneous grain fragmentation and random deformation texture. These contribute to uniform and fine grain size combined with random crystallographic orientations after the completion of recrystallization.
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