Optical switching of ferroelectric polarization is of interest for wireless and energy-efficient control of logic states.So far,this phenomenon has been widely demonstrated only in ferroelectric perovskites,while stud...Optical switching of ferroelectric polarization is of interest for wireless and energy-efficient control of logic states.So far,this phenomenon has been widely demonstrated only in ferroelectric perovskites,while studies on other emerging ferroelectrics remain limited.In this regard,the paradigmatic example of a technologically relevant ferroelectric material is HfO2.However,HfO2has a very wide bandgap,limiting light absorption.So far,the proposed strategies to enhance light absorption in HfO2-based systems are detrimental to ferroelectric properties,i.e.,bandgap lowering or on-purpose defect introduction,which reduce switchable polarization and increase the presence of leakage currents.Here,we show that good ferroelectric properties,i.e.,sizeable polarization(up to 15μC cm-2),low leakage current(under 10-6A cm-2),high endurance(up to 108 cycles)and fast switching(<50 ns),can be achieved in epitaxial Hf0.5Zr0.5O2films through an alternative strategy,BaTiO3capping.While ferroelectric properties are remarkable,we demonstrate that the presence of BaTiO3allows light absorption and the concomitant electric field generation,as supported by density functional theory calculations,which enables optical switching of polarization in Hf0.5Zr0.5O2under 405 nm illumination.It is observed that optical switching is more efficient in films with thicker BaTiO3capping layer.The high polarizability of BaTiO3contributes to minimizing degradation in the ferroelectric response of the system.The results presented here indicate that appropriate designs can be followed to obtain optical switching of polarization in ferroelectric HfO2while preserving main functional properties.展开更多
The effects of the ultrasonic treatment on the microstructure and mechanical properties of Mg-6Zn-0.5Y-2Sn alloy were investigated. The results show that the ultrasonic treatment has significant effect on the microstr...The effects of the ultrasonic treatment on the microstructure and mechanical properties of Mg-6Zn-0.5Y-2Sn alloy were investigated. The results show that the ultrasonic treatment has significant effect on the microstructure and mechanical properties of Mg-6Zn-0.5Y-2Sn alloy. The phases in Mg-6Zn-0.5Y-2Sn alloy are α-Mg, MgZn2, MgSnY, Mg2Sn, and a small amount of I-phase. With the application of ultrasonic treatment, I-phase nearly disappears, and with increasing the ultrasonic treatment power, the coarse dendrites gradually change into roundish equiaxed grains. The second phases at the α-Mg boundaries transform from coarse, semicontinuous and non-uniform to fine, discontinuous, uniform and dispersive. When the ultrasonic treatment power is 700 W, the best comprehensive mechanical properties of Mg-6Zn-0.5Y-2Sn alloy are obtained. Compared with the untreated alloy, the 0.2%tensile yield strength, ultimate tensile strength and elongation are improved by 28%, 30%and 67%, respectively.展开更多
采用溶胶-凝胶法制备Ti/Sn O_2-F电极,进行全氟辛酸(PFOA)电氧化降解的研究,实验考察了F替代Sb掺杂、电流密度、初始pH值和支持电解质对PFOA降解效率的影响。结果表明,当F替代Sb掺杂Sn O_2,电流密度为20 m A/cm^2,初始pH值3.7,支持电解...采用溶胶-凝胶法制备Ti/Sn O_2-F电极,进行全氟辛酸(PFOA)电氧化降解的研究,实验考察了F替代Sb掺杂、电流密度、初始pH值和支持电解质对PFOA降解效率的影响。结果表明,当F替代Sb掺杂Sn O_2,电流密度为20 m A/cm^2,初始pH值3.7,支持电解质为NaClO_4时,电解30 min后PFOA的降解率达98%。采用液相色谱-质谱联用(HPLC-MS/MS)和离子色谱(IC)对PFOA降解产物进行分析,解析了PFOA电氧化降解的反应机理。展开更多
The effects of trace addition of Al2O3 nanoparticles(NPs)on thermal reliabilities of Sn−0.5Ag−0.7Cu/Cu solder joints were investigated.Experimental results showed that trace addition of Al2O3 NPs could inc...The effects of trace addition of Al2O3 nanoparticles(NPs)on thermal reliabilities of Sn−0.5Ag−0.7Cu/Cu solder joints were investigated.Experimental results showed that trace addition of Al2O3 NPs could increase the isotheraml aging(IA)and thermal cyclic(TC)lifetimes of Sn−0.5Ag−0.7Cu/Cu joint from 662 to 787 h,and from 1597 to 1824 cycles,respectively.Also,trace addition of Al2O3 NPs could slow down the shear force reduction of solder joint during thermal services,which was attributed to the pinning effect of Al2O3 NPs on hindering the growth of grains and interfacial intermetallic compounds(IMCs).Theoretically,the growth coefficients of interfacial IMCs in IA process were calculated to be decreased from 1.61×10^(−10 )to 0.79×10−10 cm2/h in IA process,and from 0.92×10−10 to 0.53×10−10 cm2/h in TC process.This indicated that trace addition of Al2O3 NPs can improve both IA and TC reliabilities of Sn−0.5Ag−0.7Cu/Cu joint,and a little more obvious in IA reliability.展开更多
Al0.3CrFe1.5MnNi0.5 high entropy alloys(HEA)have special properties.The microstructures and shear strengths of HEA/HEA and HEA/6061-Al joints were determined after direct active soldering(DAS)in air with Sn3.5Ag4Ti ac...Al0.3CrFe1.5MnNi0.5 high entropy alloys(HEA)have special properties.The microstructures and shear strengths of HEA/HEA and HEA/6061-Al joints were determined after direct active soldering(DAS)in air with Sn3.5Ag4Ti active filler at 250°C for 60 s.The results showed that the diffusion of all alloying elements of the HEA alloy was sluggish in the joint area.The joint strengths of HEA/HEA and HEA/6061-Al samples,as analyzed by shear testing,were(14.20±1.63)and(15.70±1.35)MPa,respectively.Observation of the fracture section showed that the HEA/6061-Al soldered joints presented obvious semi-brittle fracture characteristics.展开更多
A series of TiO2-SnO2 nano-sized composite photo-catalysts containing Sn(9.3%-30.1%)were prepared from TiCl4and SnCl4·5H2O by using sol-gel,supercritical fluid dry and solid-phase reaction(SCFD)combination ...A series of TiO2-SnO2 nano-sized composite photo-catalysts containing Sn(9.3%-30.1%)were prepared from TiCl4and SnCl4·5H2O by using sol-gel,supercritical fluid dry and solid-phase reaction(SCFD)combination technology.Characterizations with X-ray diffraction(XRD),transmission electron microscopy(TEM)and Fourier Transform Infrared Spectroscopy(FTIR)showed that,in addition to anatase type TiO2,a new active phase(Ti,Sn)O2(with particle size of 2.0-4.3 nm)formed,and there were no SnO2 crystals observed in the range of the doping concentration studied.Photo-catalytic reaction of phenol was used as a model reaction to evaluate the catalytic activities of the obtained catalysts.Compared with pure TiO2 or Ti-Sn catalyst prepared with general sol-gel method,Ti-Sn nano-composite photo-catalyst thus obtained showed significant improvement in catalytic activity.The photo-catalytic degradation rate of phenol could reach as high as 93.5%after 7 h.The preparation conditions of the new phase(Ti,Sn)O2 were investigated and its catalytic mechanism was proposed.The photo-catalytic particles prepared using SCFD combination technology exhibited small particle size,large surface area and high activity.展开更多
将共沉淀法和固相法相结合,将Si 4+掺杂到LiNi 0.5 Mn 0.5 O 2中,合成LiNi 0.5-x Si x Mn 0.5 O 2(0≤x≤0.08)正极材料。通过XRD及精修、等离子体发射光谱(ICP)、SEM和透射电子显微镜(TEM)等方法,对合成材料的结构、成分和形貌进行分析...将共沉淀法和固相法相结合,将Si 4+掺杂到LiNi 0.5 Mn 0.5 O 2中,合成LiNi 0.5-x Si x Mn 0.5 O 2(0≤x≤0.08)正极材料。通过XRD及精修、等离子体发射光谱(ICP)、SEM和透射电子显微镜(TEM)等方法,对合成材料的结构、成分和形貌进行分析。Si 4+掺杂不仅可降低材料的锂镍混排程度,还能增强结构稳定性,且不会改变材料的形貌。以40 mA/g(0.2 C)的电流在2.5~4.5 V充放电,LiNi 0.47 Si 0.03 Mn 0.5 O 2(x=0.03)正极材料具有最好的电化学性能,不仅比容量(149.25 mAh/g)较未掺杂材料(125.44 mAh/g)提高20%,而且容量保持率在120次循环后也提高了7.7%。Si 4+掺杂能降低材料的锂镍混排程度,有利于Li+的迁移;能提高材料的结构稳定性,抑制电压的下降并减轻极化。展开更多
The humidity sensing properties of La^3+ and K^+ co-doped Ti0.9Sn0.1O2 thin films were investigated. The humidity sensitive thin films were prepared by sol-gel method on alumina substrates. The sensing behaviors of ...The humidity sensing properties of La^3+ and K^+ co-doped Ti0.9Sn0.1O2 thin films were investigated. The humidity sensitive thin films were prepared by sol-gel method on alumina substrates. The sensing behaviors of thin films were inspected at different sintering temperatures by constructing a humidity-impedance measuring system. It was found that the addition of rare earth ion La^3+ and alkali ion K^+ was beneficial for improving the humidity sensitive properties of the samples and La0.003K0.5Ti0.9Sn0.1O2 sintered at 500 ℃ for 4 h showed the best humidity sensing properties. The impedance of this thin film decreased from 109 to 104 Ω with excellent linearity in the humidity range of 11%-95%. Narrow hysteresis loop, prominent stability and high sensitivity were obtained. The effects of dopant con-tent and doping mechanism on humidity sensitivity were also discussed in terms of segregation of rare earth ions at grain boundaries and granularity of crystalline and influence of K^+ on the decrease in the intrinsic resistance of the materials, and increase in the number of wa-ter adsorption sites.展开更多
基金Financial support from the Spanish Ministry of Science,Innovation and Universities(MCIN/AEI/http://gffzzd3cc09b8251d45dfs65vqxw6xncxw6kok.ffgz.tsg.suse.edu.cn/10.13039/501100011033),through the Severo Ochoa MATRANS42(CEX2023-001263-S)and CEX2023001286-S,PDC2023-145874-I00,PID2023-147211OB-C21,PID2023-147211OB-C22 and TED2021-130453B-C21 projectsGeneralitat de Catalunya(2021 SGR 00804)+1 种基金Gobierno de Aragon project E13_23Rfinancially supported by China Scholarship Council(CSC)with No.202208310089
摘要Optical switching of ferroelectric polarization is of interest for wireless and energy-efficient control of logic states.So far,this phenomenon has been widely demonstrated only in ferroelectric perovskites,while studies on other emerging ferroelectrics remain limited.In this regard,the paradigmatic example of a technologically relevant ferroelectric material is HfO2.However,HfO2has a very wide bandgap,limiting light absorption.So far,the proposed strategies to enhance light absorption in HfO2-based systems are detrimental to ferroelectric properties,i.e.,bandgap lowering or on-purpose defect introduction,which reduce switchable polarization and increase the presence of leakage currents.Here,we show that good ferroelectric properties,i.e.,sizeable polarization(up to 15μC cm-2),low leakage current(under 10-6A cm-2),high endurance(up to 108 cycles)and fast switching(<50 ns),can be achieved in epitaxial Hf0.5Zr0.5O2films through an alternative strategy,BaTiO3capping.While ferroelectric properties are remarkable,we demonstrate that the presence of BaTiO3allows light absorption and the concomitant electric field generation,as supported by density functional theory calculations,which enables optical switching of polarization in Hf0.5Zr0.5O2under 405 nm illumination.It is observed that optical switching is more efficient in films with thicker BaTiO3capping layer.The high polarizability of BaTiO3contributes to minimizing degradation in the ferroelectric response of the system.The results presented here indicate that appropriate designs can be followed to obtain optical switching of polarization in ferroelectric HfO2while preserving main functional properties.
基金Project(cstc2015jcyj BX0036)supported by Chongqing Research Program of Basic Research and Frontier Technology,ChinaProject(51571040)supported by the National Natural Science Foundation of ChinaProject supported by the Sharing Fund of Chongqing University’s Large-scale Equipment,China
摘要The effects of the ultrasonic treatment on the microstructure and mechanical properties of Mg-6Zn-0.5Y-2Sn alloy were investigated. The results show that the ultrasonic treatment has significant effect on the microstructure and mechanical properties of Mg-6Zn-0.5Y-2Sn alloy. The phases in Mg-6Zn-0.5Y-2Sn alloy are α-Mg, MgZn2, MgSnY, Mg2Sn, and a small amount of I-phase. With the application of ultrasonic treatment, I-phase nearly disappears, and with increasing the ultrasonic treatment power, the coarse dendrites gradually change into roundish equiaxed grains. The second phases at the α-Mg boundaries transform from coarse, semicontinuous and non-uniform to fine, discontinuous, uniform and dispersive. When the ultrasonic treatment power is 700 W, the best comprehensive mechanical properties of Mg-6Zn-0.5Y-2Sn alloy are obtained. Compared with the untreated alloy, the 0.2%tensile yield strength, ultimate tensile strength and elongation are improved by 28%, 30%and 67%, respectively.
基金National Key Research and Development Program of China(2016YFB0301100)Chongqing Research Program of Basic Research and Frontier Technology(cstc2015jcyjBX0036)+1 种基金National Natural Science Foundation of China(51571040)Sharing Fund of Chongqing University’s Large-Scale Equipment
基金supported by the National Natural Science Foundation of China(Nos.52105369,61974070)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.20KJB460008)+1 种基金Natural Science Foundation of Jiangsu Province,China(No.BK20200746)NUPTSF(No.NY220077).
摘要The effects of trace addition of Al2O3 nanoparticles(NPs)on thermal reliabilities of Sn−0.5Ag−0.7Cu/Cu solder joints were investigated.Experimental results showed that trace addition of Al2O3 NPs could increase the isotheraml aging(IA)and thermal cyclic(TC)lifetimes of Sn−0.5Ag−0.7Cu/Cu joint from 662 to 787 h,and from 1597 to 1824 cycles,respectively.Also,trace addition of Al2O3 NPs could slow down the shear force reduction of solder joint during thermal services,which was attributed to the pinning effect of Al2O3 NPs on hindering the growth of grains and interfacial intermetallic compounds(IMCs).Theoretically,the growth coefficients of interfacial IMCs in IA process were calculated to be decreased from 1.61×10^(−10 )to 0.79×10−10 cm2/h in IA process,and from 0.92×10−10 to 0.53×10−10 cm2/h in TC process.This indicated that trace addition of Al2O3 NPs can improve both IA and TC reliabilities of Sn−0.5Ag−0.7Cu/Cu joint,and a little more obvious in IA reliability.
基金financial support of this work from the Ministry of Science and Technology, Taibei, China, under Projects No. MOST 105-ET-E-020002-ET, 105-2622-E-020-003-CC3
摘要Al0.3CrFe1.5MnNi0.5 high entropy alloys(HEA)have special properties.The microstructures and shear strengths of HEA/HEA and HEA/6061-Al joints were determined after direct active soldering(DAS)in air with Sn3.5Ag4Ti active filler at 250°C for 60 s.The results showed that the diffusion of all alloying elements of the HEA alloy was sluggish in the joint area.The joint strengths of HEA/HEA and HEA/6061-Al samples,as analyzed by shear testing,were(14.20±1.63)and(15.70±1.35)MPa,respectively.Observation of the fracture section showed that the HEA/6061-Al soldered joints presented obvious semi-brittle fracture characteristics.
基金The authors thank the National Natural Scir nce Foun-dation of China(No.20076004)the National Development Project of High Technology(No.2001AA322030)the Doctoral Program of Higher Education(No.2000001005)for the financial support of this project.
摘要A series of TiO2-SnO2 nano-sized composite photo-catalysts containing Sn(9.3%-30.1%)were prepared from TiCl4and SnCl4·5H2O by using sol-gel,supercritical fluid dry and solid-phase reaction(SCFD)combination technology.Characterizations with X-ray diffraction(XRD),transmission electron microscopy(TEM)and Fourier Transform Infrared Spectroscopy(FTIR)showed that,in addition to anatase type TiO2,a new active phase(Ti,Sn)O2(with particle size of 2.0-4.3 nm)formed,and there were no SnO2 crystals observed in the range of the doping concentration studied.Photo-catalytic reaction of phenol was used as a model reaction to evaluate the catalytic activities of the obtained catalysts.Compared with pure TiO2 or Ti-Sn catalyst prepared with general sol-gel method,Ti-Sn nano-composite photo-catalyst thus obtained showed significant improvement in catalytic activity.The photo-catalytic degradation rate of phenol could reach as high as 93.5%after 7 h.The preparation conditions of the new phase(Ti,Sn)O2 were investigated and its catalytic mechanism was proposed.The photo-catalytic particles prepared using SCFD combination technology exhibited small particle size,large surface area and high activity.
摘要将共沉淀法和固相法相结合,将Si 4+掺杂到LiNi 0.5 Mn 0.5 O 2中,合成LiNi 0.5-x Si x Mn 0.5 O 2(0≤x≤0.08)正极材料。通过XRD及精修、等离子体发射光谱(ICP)、SEM和透射电子显微镜(TEM)等方法,对合成材料的结构、成分和形貌进行分析。Si 4+掺杂不仅可降低材料的锂镍混排程度,还能增强结构稳定性,且不会改变材料的形貌。以40 mA/g(0.2 C)的电流在2.5~4.5 V充放电,LiNi 0.47 Si 0.03 Mn 0.5 O 2(x=0.03)正极材料具有最好的电化学性能,不仅比容量(149.25 mAh/g)较未掺杂材料(125.44 mAh/g)提高20%,而且容量保持率在120次循环后也提高了7.7%。Si 4+掺杂能降低材料的锂镍混排程度,有利于Li+的迁移;能提高材料的结构稳定性,抑制电压的下降并减轻极化。
摘要The humidity sensing properties of La^3+ and K^+ co-doped Ti0.9Sn0.1O2 thin films were investigated. The humidity sensitive thin films were prepared by sol-gel method on alumina substrates. The sensing behaviors of thin films were inspected at different sintering temperatures by constructing a humidity-impedance measuring system. It was found that the addition of rare earth ion La^3+ and alkali ion K^+ was beneficial for improving the humidity sensitive properties of the samples and La0.003K0.5Ti0.9Sn0.1O2 sintered at 500 ℃ for 4 h showed the best humidity sensing properties. The impedance of this thin film decreased from 109 to 104 Ω with excellent linearity in the humidity range of 11%-95%. Narrow hysteresis loop, prominent stability and high sensitivity were obtained. The effects of dopant con-tent and doping mechanism on humidity sensitivity were also discussed in terms of segregation of rare earth ions at grain boundaries and granularity of crystalline and influence of K^+ on the decrease in the intrinsic resistance of the materials, and increase in the number of wa-ter adsorption sites.