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Upconversion fluorescence modulation of CaTiO_(3):Yb^(3+)/Er^(3+)nanocubes via Zn^(2+)introduction

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Optoelectronics Letters 2022年第3期18卷 129-134页

作者： MU Jiajia LIU Jinyu gao lili School of Science Beihua UniversityJilin 132013China

To investigate the effect of Zn^(2+)ions on the luminescence properties of rare earth(RE)doped calcium titanate materials,CaTiO_(3):Yb^(3+)/Er^(3+)/Zn^(2+)nanocubes with uniform size were prepared by solvothermal method in this *** were respectively characterized by X-ray diffractometer(XRD),scanning electron microscope(SEM),photoluminescence(PL)spectroscopy and their fluorescence *** results show that the average size of the nanocubes is about 550 nm×650 nm×850 nm with good upconversion luminescence(UCL)*** 980 nm laser excitation,the effects of the ratio between activator Er^(3+)and sensitizer Yb^(3+)and Zn^(2+)doping on the upconversion fluorescence properties were investigated,and the optimal ion ratio was *** results of steady-state spectra show that the strongest fluorescence intensity of CaTiO_(3):Yb^(3+)/Er^(3+)was obtained with the addition of 10 mol%Zn^(2+)at a Yb^(3+)/Er^(3+)molar doping ratio of 3:0.3,which was attributed to the crystal field asymmetry generated by the introduction of Zn^(2+)*** energy transfer and upconversion mechanism between Yb^(3+)and Er^(3+)ions in CaTiO_(3) nanocubes were investigated by analyzing the upconversion fluorescence kinetics.

关键词： properties kinetics doping

Ni_(2)P/MoS_(2) interfacial structures loading on N-doped carbon matrix for highly efficient hydrogen evolution

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Green Energy & Environment 2022年第4期7卷 829-839页

作者： Yuelong Xu Ran Wang Zhan Liu lili gao Tifeng Jiao Zhenfa Liu State Key Laboratory of Metastable Materials Science and Technology Yanshan University438West Hebei StreetQinhuangdao066004China Hebei Key Laboratory of Applied Chemistry School of Environmental and Chemical EngineeringYanshan University438West Hebei StreetQinhuangdao066004China Hebei Engineering Research Center for Water Saving in Industry Shijiazhuang050081China Institute of Energy Resources Hebei Academy of SciencesShijiazhuang050081China

Electrochemical catalysts for the hydrogen evolution reaction(HER) have attracted increasing attentions. Noble metal-free cocatalysts play a vital role in HER applications. Herein, a novel strategy to prepare a Ni_(2)P/MoS_(2) cocatalyst through a simple hydrothermal-phosphorization method was reported, and the prepared cocatalyst was then loaded on an N-doped carbon substrate with excellent conductive performance. The large surface area of the carbon substrate provided many active sites, and the interface between Ni_(2)P and MoS_(2) improved the catalytic performance for the HER. Compared with pure Ni_(2)P catalyst and MoS_(2) catalyst, the prepared Ni_(2)P/MoS_(2) cocatalyst exhibited enhanced catalytic performance. In addition, the results indicate that the prepared cocatalyst has a wide p H range and low onset potential values of 280, 350 and40 m V in acidic, phosphate-buffered saline and alkaline solutions, respectively, and the corresponding Tafel slopes are 75, 121 and 95 mV dec^(-1),respectively. Density functional theory(DFT) was adopted to calculate the hydrogen adsorption free energy(ΔG_(H)^(*)). The results showed that the interface between Ni_(2)P and MoS_(2) reduced ΔG_H^(*), which was beneficial to the adsorption of hydrogen. Present preparation of cocatalysts with unique interfaces provides a new strategy for improving the catalytic performance of HER.

关键词： MoS_(2) Ni_(2)P Hydrogen evolution Electrochemical performance Density functional theory

Control the growth of Fe3O4 on the surface of saponite and its redox effect on Cr(VI)

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Progress in Natural Science:Materials International 2023年第5期33卷 701-709页

作者： Ritong Huang Limei Wu Xiao Li Ning Tang Xiaolong Wang lili gao School of Materials Science and Engineering Shenyang Jianzhu University School of Mechanical Engineering Shenyang Jianzhu University

In this paper, Magnetite/Saponite(Fe3O4/Sap) composites were prepared by hydrothermal synthesis and coprecipitation. The prepared Fe3O4/sap composites had high purity and good crystallinity, and nano-Fe3O4was uniformly dispersed on the surface of saponite. Moreover, the removal efficiency of Fe3O4/Sap composites for Cr(VI) in water was evaluated. This study revealed the existence of abundant oxygen vacancies and hydroxyl groups on the surface of Saponite. During the synthesis of Fe3O4on the surface of Sap, the multi-directional crystallization can be controlled to increase the reaction activity of the system. Besides, the prepared Fe3O4/Sap composites provided more reactive edges compared to Fe3O4in the process of removing Cr(VI). The removal amount of Cr(VI) was found to be 17.95 mg/g. The successful preparation of the Fe3O4/Sap composites and the revelation of the Cr(VI) adsorption mechanism are of great significance for the efficient and green removal of heavy metal pollutants in sewage.

关键词： Fe3O4 Saponite Oxygen vacancy Redox Cr (VI)

A facial strategy to efficiently improve catalytic performance of CoFe_(2)O_(4) to peroxymonosulfate

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Journal of Environmental Sciences 2022年第6期34卷 1-13页

作者： lili gao Jieqiong Deng Tong Li Kai Qi Jiandong Zhang Qun Yi College of Environmental Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China College of Biomedical Engineering Taiyuan University of TechnologyTaiyuan 030024China

Cobalt iron spinel(CoFe_(2)O_(4)) has been considered as a good heterogeneous catalysis to peroxymonosulfate(PMS) in the degradation of persistent organic pollutants due to its magnetic properties and good chemical stability. However, its catalytic activity needs to be further improved. Here, a facial strategy, “in-situ substitution”, was adopted to modify CoFe_(2)O_(4) to improve its catalytic performance just by suitably increasing the Co/Fe ratio in synthesis process. Compared with CoFe_(2)O_(4), the newly synthesized Co_(1.5)Fe_(1.5)O_(4), could not only significantly improve the degradation efficiency of phenol, from 50.69 to 93.6%, but also exhibited more effective mineralization ability and higher PMS utilization. The activation energy advantage for phenol degradation using Co_(1.5)Fe_(1.5)O_(4)was only 44.2 k J/mol, much lower than that with CoFe_(2)O_(4)(127.3 k J/mol). A series of related representations of CoFe_(2)O_(4) and Co_(1.5)Fe_(1.5)O_(4) were compared to explore the possible reasons for the outstanding catalytic activity of Co_(1.5)Fe_(1.5)O_(4). Results showed that Co_(1.5)Fe_(1.5)O_(4)as well represented spinel crystal as CoFe_(2)O_(4)and the excess cobalt just partially replaced the position of iron without changing the original structure. Co_(1.5)Fe_(1.5)O_(4) had smaller particle size(8.7 nm), larger specific surface area(126.3 m^(2)/g), which was more favorable for exposure of active sites. Apart from the superior physical properties, more importantly, more reactive centers Co(Ⅱ) and surface hydroxyl compounds generated on Co_(1.5)Fe_(1.5)O_(4), which might be the major reason. Furthermore, Co_(1.5)Fe_(1.5)O_(4) behaved good paramagnetism, wide range of pH suitability and strong resistance to salt interference, making it a new prospect in environmental application.

关键词： CoFe_(2)O_(4) Co_(1.5)Fe_(1.5)O_(4) In-situ substitution Peroxymonosulfate(PMS) Advanced oxidation processes(AOPs)

Preparation of α-High Strength Gypsum from Flue Gas Desulfurization Gypsum Pretreated by Hydrothermal-aging Method

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Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 75-81页

作者：苏一鑫 gao lili 陈学青 LI Zhishui 李雲 CAO Jilin Engineering Research Center of Seawater Utilization Technology of Ministry of Education School of Chemical Engineering and TechnologyHebei University of TechnologyTianjin 300130China Heze Center for Disease Control and Prevention Heze 274010China Tianjin Bohua Yongli Chemical Industry Co. Ltd.Tianjin 300452China

The synthesis of α-calcium sulfate hemihydrate (α-CSH) from flue gas desulfurization (FGD)gypsum is a good way to realize the comprehensive utilization of FGD gypsum. To obtainα-CSH with the satisfactory performances, a facile hydrothermal-aging pretreatment process for FGD gypsum raw materials was proposed, where FGD gypsum was firstly hydrothermally converted to α-CSH whiskers, and α-CSH whiskers were further hydrated to synthesize CaSO4·2H2O (CSD) by aging under the regulation of N,N'-methylenebisacrylamide (MBA). The effects of aging time, MBA addition, aging temperature, and pH on the morphology of the synthesized CSD were investigated. The synthesized CSD crystals exhibit highly uniform prismatic morphology with the length of ca 100μm and the whiteness of 91.56%. The regulation mechanism of MBA was also illustrated. The synthesized CSD crystals with prismatic morphology were further used as raw materials to synthesize the short columnar α-CSH. The absolute dry compressive strength of paste prepared from the short columnar α-CSH is 40.85 MPa, which reaches α40 strength grade.

关键词： flue gas desulphurization gypsum α-calcium sulfate hemihydrate hydrothermal-aging method N,N'-methylenebisacrylamide prismatic CSD

Anand Parameters Determination for SnAgCu Solder Bearing Micro-amounts Rare Earth Ce

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Chinese Journal of Mechanical Engineering 2010年第2期23卷 257-262页

作者： ZHANG Liang XUE Songbai gao lili CHEN Yan YU Shenglin SHENG Zhong College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Harbin Welding Institute Harbin 150080 China The 14th Research Institute China Electronics Technology Group Corporation Nanjing 210013 China

SnAgCu solder system with the addition of rare earth Ce, which has better thermo-mechanical properties compared to those of SnPb solder, is regarded as one of the promising candidates for electronic assembly. Moreover, the SnAgCuCe solder alloys can provide good quality joints with Cu substrates. However, there is few report of the constitutive model for SnAgCu solder bearing micro-amounts rare earth Ce. In this paper, the unified viscoplastic constitutive model, Anand equations, is used to represent the inelastic deformation behavior for SnAgCu and SnAgCuCe solders. In order to obtain the acquired data for the fitting of the material parameters of this unified model, a series of experiments of constant strain rate test were conducted under isothermal conditions at different temperatures. The Anand parameters of the constitutive equations for SnAgCu and SnAgCuCe solder were determined from separated constitutive relations and experimental results. Nonlinear least-square fitting was selected to determine the model constants. And the simulated results were then compared with experimental measurements of the stress-inelastic strain curves： excellent agreement was found. The model accurately predicted the overall trend of steady-state stress-strain behavior of SnAgCu and SnAgCuCe solders for the temperature ranges from 25℃ to 150 ℃, and the strain rate ranges from 0.01 s^-1 to 0.001 s ^-1. It is concluded that the Anand model can be applied for representing the inelastic deformation behavior of solders at high homologous temperature and can be recommended for finite element simulation of the stress-strain response of lead free soldered joints. Based on the Anand model, the investigations of thermo-mechanical of SnAgCu and SnAgCuCe soldered joints in fine pitch quad flat package by finite element code were done under thermal cyclic loading, it is found that the reliability of SnAgCu soldered joints can be improved remarkably with addition of rare earth Ce. The results ma

关键词： Anand equations constitutive relations SnAgCuCe solders rare earth reliability

Effect of Thermal Cycling on Properties and Microstructure of SnAgCuCe Soldered Joints in QFP Devices

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 561-566页

作者： ZHANG Liang XUE Songbai gao lili ZENG Guang YU Shenglin SHENG Zhong College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China School of Mechanical ＆ Electrical Engineering Xuzhou Normal University Xuzhou 221116 China The 14th Research Institute China Electronics Technology Group Corporation Nanjing 210013 China

Increasing global concern about the environment is bringing regulatory （European directives） and consumer （＂green products＂） pressure on the electronics industry in Europe and Japan to reduce or completely eliminate the use of lead （Pb） in products. Among all lead-free solder alloys, SnAgCu solder system, which has better thermo-mechanical properties compared with those of SnPb solder, is proven to be one of the promising candidates for electronic assembly. Previous work also revealed that adding a small amount of rare earth Ce into SnAgCu solder can visibly improve the properties and inhibit the excessive growth of the intermetallic compound layer. Thermal fatigue properties of SnAgCuCe soldered joints in QFP devices under thermal conditions have been investigated by finite element method and experiments. Based on creep model of low stress and high stress, corresponding creep subroutine was established for simulating the stress and strain response of SnAgCuCe soldered joint from -55 ℃ to 125 ℃, and fatigue life was calculated using creep fatigue life prediction equation. Moreover, thermal cycling experiments were conducted, the experimental results were found to be close to the simulated results. In addition, the tensile force of SnAgCuCe soldered joints decreased with increasing number of thermal cycles, and the fracture mechanism transformed from toughness fracture to brittle intergranular fracture. Moreover the tensile force changes and fracture microstructure evolution could benefit the quantitative evaluations of the mechanical performances of lead-free soldered joints under thermal cycling loadings.

关键词： finite element method creep equation thermal cycling fatigue life

Preparation and Characterization of Ag_2S/PMMA Nanocomposites by Microemulsion

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Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 175-179页

作者： Yuzhen Li Lizhen gao Wenjun Chen Weike Zhang lili gao Yanqing Yang Likun Shang Meilu Wang College of Environmental Science and Engineering Taiyuan University of Technology School of Mechanical Engineering University of Western Australia35 Stirling HighwayCrawleyWA 6009Australia Department of Neurology Shanxi Provincial People's Hospital

Ag2S nanoparticles in polymethyl methacrylate （PMMA） are prepared in n-heptane/sodium bis（2-ethyl- hexyl）sulfosuccinate/water microemulsions. The Ag2S nanoparticles dispersed in the polymer are characterized by FT-IR spectrum, UV-Vis absorption spectroscopy, transmission electron microscopy （TEM）, and X-ray powder diffraction （XRD）. The FT-IR spectrum shows that the composite has the characteristic bands of nano-Ag2S and pure PMMA. The TEM photograph of the sample shows that the Ag2S nanoparticles are elliptical. The phase structure of the composite is characterized by XRD, which reveals that Ag2S particles are formed. The UV-Vis absorption recorded at various times indicates an initial rapid formation of the nanoparticles and the quantum confinement effect of Ag2S nanoparticles.

关键词： Nanoparticle Nanocomposite Coating

MECHANICAL PROPERTIES OF FINE PITCH DEVICES SOLDERED JOINTS BASED ON CREEP MODEL

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Chinese Journal of Mechanical Engineering 2008年第6期21卷 82-85页

作者： ZHANG Liang XUE Songbai HAN Zongjie WANG Jianxin gao lili SHENG Zhong College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Nonlinear analyses of quad flat package （QFP） on printed circuit board （PCB） assemblies subjected to thermal cycling conditions are presented. Two different solders are considered, namely, Sn37Pb and Sn3.5Ag. The stress and strain response of fine pitch devices soldered joints was investigated by using finite element method based on Garofalo-Arrheninus model. The simulated results indicate creep distribution of soldered joints is not uniform, the heel and toe of soldered joints, the area between soldered joints and leads are the creep concentrated sites. The similar phenomena of stress curves simulated based on Garofalo-Arrheninus model and Anand equations is confirmed, and the creep strain value of Sn3.5Ag soldered joints is lower than that of Sn37Pb soldered joints. Thermal cycling results show that Sn3.5Ag strongly outperforms Sn37Pb for QFP devices under the studied test condition. This is well matched with the experimental outcome analyzed. In addition, the soldered devices were tested by micro-joints tester, the tensile strength of Sn3.5Ag soldered joints is found to be higher than that of Sn37Pb soldered joints. By analyzing the fracture microstructure of soldered joints, it is found that fracture mechanism of Sn3.5Ag soldered joints is toughness fracture, while fracture mechanism of Sn37Pb soldered joints includes brittle fracture and toughness fracture. The results of this study provide an important basis of understanding the mechanical properties of fine pitch devices with traditional Sn37Pb and Sn3.5Ag lead-free soldered joints.

关键词： Finite element method creep properties tensile strength fracture microstructure