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Preparation and growth mechanism of centimeter-scale (AgxCu1-x)2ZnSnS4 single crystals via a molten salt method

CRYSTENGCOMM 2024年第10期26卷 1418-1429页

作者： Liao, Jun Ye, Sihao Zhu, Xupeng fu, Wenfeng Xue, shuwen Qi, Jing Zhang, Jun Lingnan Normal Univ Sch Phys Sci & Technol Zhanjiang 524048 Peoples R China Lanzhou Univ Sch Mat & Energy Lanzhou 730000 Peoples R China

Kesterite Cu2ZnSnS4 (CZTS) is considered as one of the most promising thin-film solar cell and photocatalytic materials;however, its efficiency in practical photoelectric applications is often seriously limited by the presence of large numbers of Cu-Zn antisite defects. Alloying with Ag to fabricate Ag-alloyed CZTS ((AgxCu1-x)(2)ZnSnS4, ACZTS) can reduce the Cu-Zn antisite defects in CZTS, but few research studies have been able to separately clarify the effect of Ag content and growth temperature on large-sized (AgxCu1-x)(2)ZnSnS4 single crystals. In this study, centimeter-scale high-quality ACZTS single crystals were synthesized via an Ag-alloying strategy by a molten salt method for the first time. The results showed that the synthesized ACZTS have a high-quality single-crystal structure. A series of experiments was performed using various characterization techniques and it was found that Ag content and growth temperature were crucial in determining the size of ACZTS single crystals obtained through a molten salt method and that the associated CZTS base generated at high temperature was beneficial for further ACZTS single-crystal growth in this high-temperature environment. The experimental results showed that the growth mechanism of ACZTS crystals prepared using a molten salt method could be attributed to a type of epitaxial growth process. Our study provides a promising approach for growing large-sized ACZTS single crystals with high quality that can provide a potential single-crystal platform for the study of light-emitting diodes, photocatalytic hydrogen production, etc.

关键词： Single crystals

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Featured Neoarchean granitoid association in the central North China Craton: An indicator of warm plate subduction

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GEOLOGICAL SOCIETY OF AMERICA BULLETIN 2023年第1-2期135卷 295-309页

作者： Sun, Guozheng Hu, Yalu Liu, shuwen Li, Sanzhong fu, Jinghao Gao, Lei Ocean Univ China Frontiers Sci Ctr Deep Ocean Multispheres & Earth Key Lab Submarine Geosci & Prospecting Tech MOE Qingdao 266100 Peoples R China Ocean Univ China Coll Marine Geosci Qingdao 266100 Peoples R China Qingdao Natl Lab Marine Sci & Technol Lab Marine Mineral Resources Qingdao 266237 Peoples R China Peking Univ Key Lab Orogen Belts & Crustal Evolut Minist Educ Beijing 100871 Peoples R China China Geol Survey Dev Res Ctr Beijing 100037 Peoples R China Southwest Petr Univ Sch Geosci & Technol Chengdu 610500 Sichuan Peoples R China China Univ Geosci Beijing Sch Earth Sci & Resources Beijing 100083 Peoples R China

Diverse Neoarchean granitoid assem-blages, which generally include tonalites- trondhjemites-granodiorites (TTGs) and various K-rich granitoids, are prevalent in most basement terranes of the North China Craton. However, the Hengshan terrane is an exceptional case in the North China Craton;it is dominated by late Neoarchean sodic di-orite-TTGs (DTTGs) and sanukitoids. These sanukitoids are the only high-K granitoids and show Mg-rich chemical features. The late Neoarchean DTTGs and sanukitoids were generated at ca. 2486-2537 Ma and show an intimate spatial association. The granitoid assemblages of the DTTGs and sanukitoids are characterized by high Mg# [100 x Mg/ (Mg + Fe-total)] values (43-65) and enriched in light rare earth elements, large ion litho-phile elements, heterogeneous zircon Lu-Hf (epsilon Hf = -1.6 to +7.4), and whole-rock Sm-Nd (epsilon Nd = +0.9 to +4.2) isotopic components, which indicates that they may be derived from varying degrees of interactions between mantle peridotite and subduction-related ma-terials. Combined with the relatively high ap-parent geothermal gradient (similar to 17 +/- 2 degrees C/km) and the relatively low basal heat flow of con-tinental crust (similar to 25 +/- 5 mW m(-2)), the crust -mantle interaction process indicates that the occurrence of late Neoarchean high-Mg mag-matism was closely related to warm oceanic slab subduction in the Hengshan terrane, and the featured lithological association of DTTGs and sanukitoids most likely devel-oped in the active continental margin at the end of the Archean.

关键词： Zircon

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Non thermoplastic 3D molding based on coordination crosslinking for on-demand customization carboxymethyl chitosan-based packaging bags

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FOOD PACKAGING AND SHELF LIFE 2025年 48卷

作者： Deng, Yongfu Luo, shuwen Zhao, Wenxin Wei, fuxiang Xu, Chuanhui fu, Lihua Lin, Baofeng Guangxi Univ Sch Chem & Chem Engn Nanning 530004 Peoples R China

The exhaustion of non-renewable resource and the environment pollution of plastic wastes have become a global crisis. Natural polysaccharide is expected to be sustainable and biodegradable alternative to petroleum-based plastics. However, the thermal processing of polysaccharides especially 3D film formation is challenging due to their lack of thermoplasticity. Herein, a novel reverse mold crosslinking film-forming strategy for the preparation of polysaccharide-based 3D film was proposed, where the role of rapid crosslinking molding is similar to that of cooling molding during injecting processing. Through this non-thermal processing, carboxymethyl chitosan/polyvinyl alcohol/Zn (CMCS/PVA/Zn) 3D films were successfully prepared. The CMCS/PVA/Zn exhibits excellent mechanical performance, water resistance, and transparency, meeting the performance requirement in food packaging bags. Moreover, CMCS/PVA/Zn can be customized on-demand, such as shape, size, color, and function, by adjusting the mold or adding functional additive. Notable, multiple carboxyl polysaccharides and metal ions can be used for the preparation of 3D films by this non-thermal processing method, showing great universality. And this method is more energy-efficient than thermal processing and preservers the bioactivity of polysaccharides and additives. Therefore, this innovative approach to polysaccharide processing offers a promising potential for the creation of polysaccharide-based food packaging bags as a sustainable alternative to non-degradable plastic bags.

关键词： Polysaccharides 3D molding Non-thermal processing On-demand customization Packaging bags

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Performance of variance estimators in the analysis of longitudinal data with a large cluster size

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JOURNAL OF STATISTICAL COMPUTATION AND SIMULATION 2022年第1期92卷 1-18页

作者： Hu, shuwen Wang, You-Gan fu, Liya Queensland Univ Technol Sch Math Sci Brisbane Qld Australia Xi An Jiao Tong Univ Sch Math & Stat Xian Peoples R China

Generalized estimating equations (GEE) is a widely used method for analysing longitudinal data, and the sandwich method is often used to estimate the variance-covariance matrix of the regression coefficient estimators. However, the sandwich method relies on the residual products as an estimator for the true covariance of the responses, and the estimator becomes singular and sparse when the cluster size (n) becomes larger. We carry out a large set of simulation studies to address the question, when the cluster size becomes large, whether the sandwich estimator and their modified versions are still valid when a sparse or singular matrix is used as an estimate of the true covariance of the responses. The performance of smooth bootstrap which involves perturbing the estimating functions is also worth to be investigated when the cluster size is large. Two datasets are analysed to illustrate these findings.

关键词： Covariance estimate large cluster size generalized estimating equations smooth bootstrap regularized sandwich estimate

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The impact of 10 MeV electron irradiation on switching characteristics of SiC MOSFET devices

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MICROELECTRONICS RELIABILITY 2025年 171卷

作者： fu, Xianghe Guo, shuwen Peng, Wenbo Zhao, Xiaolong Zhu, Quanzhe He, Yongning Xi An Jiao Tong Univ Fac Elect & Informat Engn Sch Microelect Key Lab Micronano Elect & Syst Integrat Xian City Xian 710049 Shaanxi Peoples R China Shannxi Adv Semicond Technol Ctr Co Ltd Xian 710077 Shaanxi Peoples R China

The rigorous requirements of applications such as deep space exploration, nuclear power plants, and nuclear submarines, pose stringent demands on the radiation resistance of power devices. SiC exhibits excellent radiation resistance compared to Si, while the application of SiC power devices in electron radiation environments still requires further theoretical and experimental refinement. In particular, there is a lack of research on the impact of electron radiation on the switching characteristics of SiC power devices. In this work, we studied the electron radiation effects on the dynamic and static characteristics of SiC VDMOSFET via theoretical modeling, simulation analysis, and 10 MeV irradiation experiments. We further analyzed their radiation damage mechanisms, especially for the damage on the gate structure and drift region. Radiation-induced damage to the gate oxide is the main cause of changes in device characteristics. The experimental results demonstrate a nonlinear correlation between the radiation dose and the threshold voltage of SiC MOSFET devices. With the increase in radiation dose, the switching-on delay time and switching-off voltage/current change rate of the devices decrease, while the switching-off delay time and switching-on voltage/current change rate increase. Consequently, there is a reduction in switching-on losses and an increase in switching-off losses, which affect the thermal generation during the switching process of the device. We also conducted a comparative analysis with Si MOSFET devices. The dynamic and static characteristics of SiC MOSFET devices are found to be less affected by radiation compared to Si MOSFET devices, exhibiting superior radiation resistance.

关键词： SiC MOSFET devices Electron beam irradiation effect Switching characteristic Reliability

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Non-Line-of-Sight Localization of Passive UHF RFID Tags in Smart Storage Systems

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2022年第10期21卷 3731-3743页

作者： Gui, Linqing Xu, shuwen Xiao, fu Shu, Feng Yu, Shui Nanjing Univ Posts & Telecommun Coll Comp Nanjing 210003 Peoples R China Nanjing Univ Posts & Telecommun Jiangsu High Technol Res Key Lab Wireless Sensor Nanjing 210003 Peoples R China Nanjing Univ Sci & Technol Sch Elect & Opt Engn Nanjing 210094 Peoples R China Univ Technol Sydney Sch Comp Sci Sydney NSW 2007 Australia

The UHF radio-frequency identification (RFID) has gained growing attention for tagged object localization in smart storage systems. Due to Non-Line-Of-Sight (NLOS) condition, it is challenging to accurately locate the position of tags inside closed spaces. In this paper, we propose a precise and cost-effective solution for tagged object localization in closed spaces, using only received signal strength (RSS) information. We establish a RSS profile for each tag and discover some important features of RSS profiles including uniqueness, time-variation, column-dependence and waveform-similarity. Based on these features, we propose a reference-free RSS-profile (RFRP) localization scheme. The advantage of our propose scheme is to accurately localize multiple tags in closed spaces by overcoming the challenges including the lack of pre-deployed reference tags, NLOS propagation, multi-path propagation and coupling effect. The RFRP scheme first roughly estimates tags' coordinates based on Peak Asymmetry Factor, then acquires reference-tag substitutes through the similarity of RSS sequences. Subsequently, our scheme refines the relative positions of all tags by these substitutes. Finally all tags' absolute positions are estimated through a RSS-ranging model. Extensive experiment results demonstrate that our approach can achieve high ordering accuracy and localization accuracy for the tags inside closed spaces.

关键词： Location awareness Radiofrequency identification Antennas Antenna arrays Phase measurement Hardware Antenna measurements UHF RFID non-line-of-sight (NLOS) localization RSS

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Corrosion Dynamics of Low Carbon Steel in Salt Spray Environment

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PROTECTION OF METALS AND PHYSICAL CHEMISTRY OF SURFACES 2023年第4期59卷 729页

作者： Ding, Cheng Liu, Jin Zhang, Xiqing Wang, Jiaji Li, Lili fu, Kuijun Chen, shuwen Univ Sci & Technol Liaoning Sch Mat & Met Anshan 114000 Liaoning Peoples R China State Key Lab Met Mat Marine Equipment & Applicat Anshan 114000 Liaoning Peoples R China

In order to study the corrosion dynamics of low carbon steel in neutral salt spray environment, the low carbon steel samples were carried out neutral salt spray corrosion test (SST). The corrosive behavior of low carbon steel was examined by scan electron microscopy, electrochemical impedance spectra, and potentiodynamic polarization, and the salt spray corrosion dynamics laws of low carbon steel were discussed. SST results showed that as the corrosion progresses, the rust layers will become dense, forming a "scab" structure, and forming an occluded corrosion zone with the substrate, resulting in increased corrosion rate. The newly generated inner rust layers were loose and expanded outward, caused the "scab" structure to peel off, and this has a certain periodicity. After corrosion, the surface of the substrate is pit-shaped, which uniformity is poor. Electrochemical tests showed that the corrosion process of low carbon steel in salt spray environment was mainly controlled by cathode diffusion, and the corrosion rate was relatively stable.

关键词： low carbon steel salt spray corrosion rust layers analysis electrochemical test

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Snow-Enhancement Conditions and Seeding Simulation of Stratiform Clouds in the Bayanbulak Test Area in China

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Journal of Meteorological Research 2024年第6期38卷 1078-1092页

作者： Lei WEI Yueqin SHI Weiguo LIU Gang LI Wenhao HU Miao CAI Hengchi LEI shuwen ZHAO Yuan fu CMA Weather Modification Centre China Meteorological Administration(CMA)Beijing100081China Meteorological Bureau of Bayingol Mongolian Autonomous Prefecture Korla841000China Institute of Atmospheric Physics Chinese Academy of SciencesBeijing100029China Zhejiang Meteorological Observatory Hangzhou310000China

In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding *** objective was to elucidate the mechanism of snowfall enhancement in stratiform clouds in the Bayanbulak test area of Xinjiang,*** results indicated that the optimal seeding time was the early stages of weather system *** this case,the optimal seeding zone was identified as the northwest of the test area,especially near the cloud top(altitudes between 3500 and 4000 m,temperatures range−11 to−15℃),and the ideal concentration of catalyst was with ice crystal density of 1.0×10^(7)kg^(−1)within the target *** such conditions,the total precipitation rate in the seeding-affected area increased to 50.1 mm h^(−1).The results also showed that the favorable seeding region was featured by high content of supercooled water and low population of natural ice crystals,where artificial ice crystals could substantially increase the *** augmentation typically appeared in a unimodal pattern,with the peak formed within 2–3 h after *** in the ice–water mixed zone of a supercooled cloud facilitated rapid ice crystal growth to snow-flake pieces via the Bergeron process,which in turn consumed more supercooled water via collision–coalescence with cloud water ***,the intensive consumption of supercooled water impeded the riming process and reduced the formation of graupel particles within the *** dispersion of artificial ice crystals extended over tens of kilometers horizontally;however,in the vertical direction most particles remained approximately 1 km below the seeding layer,due to limited vertical ascent rate in the stratiform clouds restricting upward movement of artificial ice *** above results help better understand the snowfall enhancement mechanism in stratiform clouds and facilitate related weather modification practice.

关键词： cloud seeding condition artificial ice crystal seeding simulation snow enhancement effect

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High Responsivity Analysis of 4H-SiC Phototransistor

IEEE SENSORS LETTERS

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IEEE SENSORS LETTERS 2025年第4期9卷

作者： Huang, Danyang Zhao, Xiaolong Guo, shuwen fu, Xianghe Cui, Peiwen Ye, Sien Yu, Zixia He, Yongning Xi An Jiao Tong Univ Sch Microelect Key Lab Micronano Elect & Syst Integrat Xian City Xian 710049 Peoples R China

The performance of a 4H-SiC n-p-n phototransistor with a 30-mu m thick collector under different bias voltages, light intensities, and temperatures is meticulously studied in this letter. The responsivity of the device to 360-nm incident light is improved to 2.02 x 10(4) A/W with 37 V bias voltage. Bias voltage and incident light intensity have a synergistic effect on the device's responsivity. As the bias voltage increases, the responsivity of the device increases drastically at low incident light intensities. In contrast, the increasing trend slows down at high intensities due to the increased concentration of carriers in the base region, causing the neutral region to widen. The device is capable of responding linearly to 360 nm light with an intensity range exceeding 5 orders of magnitude at 5 V. High-temperature detection characterization indicates that the device biased at 21 V has a responsivity of 2.5 x 10(4) A/W at 453 K, which provides experimental evidence for the 4H-SiC phototransistor's high-temperature detection ability.

关键词： Photoconductivity Dark current Phototransistors Temperature Junctions Detectors Temperature measurement Fabrication Voltage measurement Performance evaluation Electromagnetic wave sensors phototransistor silicon carbide temperature-dependence ultraviolet detection

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Bridging the top-down and bottom-up approaches to smart urbanization? A reflection on Beijing's Shuangjing International Sustainable Development Community Pilot

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INTERNATIONAL JOURNAL OF URBAN SCIENCES 2023年第Sup1期27卷 101-123页

作者： Zhou, shuwen fu, Haokun Tao, Shanshan Han, Yanan Mao, Mingrui Univ Oxford Linacre Coll Oxford England Beijing Urban XYZ Technol Co Ltd Beijing Peoples R China Beijing Community Res Ctr Beijing Peoples R China

The relation between planning and smart city development is interwoven. On the one hand, planning is being digitalized and 'smartificated', but threatened by the growing dominance of IT corporations in urban development. On the other hand, bottom-up smart initiatives at the neighbourhood level are emerging to challenge top-down control, but the relation between top-down and bottom-up approaches is conflicting and often disconnected. In the Chinese context, a newly established neighbourhood planning mechanism - community duty planners (CDPs) - appears to open up opportunities for bridging bottom-up and top-down approaches to smart city development. In Beijing, the CDPs are institutionalized under Beijing's Refined Urban Management (RUM) framework which aims to improve the city's built environment and quality of living. The CDPs play the role of intermediary actors connecting local government with the communities. The article is a reflection on the Shuangjing International Sustainable Development Community Pilot and the CDPs of Shuangjing Neighbourhood. It describes and reflects on how planning institutions can influence smart city development at the neighbourhood level and how bottom-up initiatives can be connected to long-term top-down plans.

关键词： Smart cities ICT sustainable development urban planning urbanization China

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