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
One prominent cathode material utilized in commercial sodium-ion batteries is the O3-type NaNi0.5Mn0.5O2.The application of this material is hindered by multistage phase transitions and insufficient air stabi...One prominent cathode material utilized in commercial sodium-ion batteries is the O3-type NaNi0.5Mn0.5O2.The application of this material is hindered by multistage phase transitions and insufficient air stability.In this study,an innovative O3-type NaNi0.5Mn0.5O2,derived from Ni-MOFs (referred to as M-NNMO),has been developed as a cathode material for sodium-ion batteries.The M-NNMO cathode exhibits a discharge specific capacity of 124 mAh·g-1at a rate of0.1C within 2.0 to 4.0 V.Furthermore,this material demonstrates an impressive capacity retention of 75%after undergoing 100 cycles.Complex phase transitions can be inhibited and ion diffusion rates can be increased simultaneously by Ni-MOFs through the enhancement of transition metal-oxygen bonding and the rise n Na layer gap,which are in charge of the remarkable performance improvement.Importantly,the enhanced stability of the M-NNMO transition metal layer based on the uniquestructural properties of Ni-MOFs in air stability tests.This work will provide theoretical guidance to design sodiumion battery cathode materials with superior performance.展开更多
In order to produceα-calcium sulfate hemihydrate(α-CaSO4·0.5H2O)whiskers with high aspect ratios,a minor amount of CuCl2·2H2O was used as the modifying agent in the process of hydrothermal treatment of cal...In order to produceα-calcium sulfate hemihydrate(α-CaSO4·0.5H2O)whiskers with high aspect ratios,a minor amount of CuCl2·2H2O was used as the modifying agent in the process of hydrothermal treatment of calcium sulfate dihydrate(CaSO4·2H2O)precursor.The presence of 2.60×10–3 mol/L CuCl2·2H2O resulted in the increase of the aspect ratios ofα-CaSO4·0.5H2O whiskers from 81 to 253.The preferential adsorption of Cu2+on the negative{110}and{100}facets ofα-CaSO4·0.5H2O crystal structures was confirmed by EDS and XPS.And ATR-FTIR demonstrated the ligand adsorption of Cu2+on the surface ofα-CaSO4·0.5H2O whiskers.The experimental results reveal that the whiskers with high aspect ratios are attributed to the adsorption of Cu2+,which promotes the 1-D growth ofα-CaSO4·0.5H2O whiskers along the c axis.展开更多
Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption,XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Z...Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption,XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Zr0.5Ti0.5Al0.5O2 catalysts was evaluated using the simulated gases. The results show that ZTA samples exhibit higher specific surface area,larger pore volume and proper surface acidic amount and acidity in comparison with ZT. The results of the catalytic test indicate that Pt/ZT and Pt/ZTA catalysts exhibit excellent low-temperature catalytic activity and lower light-off temperatures of hydrocarbon,carbon monoxide and nitrogen oxides,especially better conversion for nitrogen oxides (NOx). The addition of Al2O3 into ZT enhanced the anti-aging property of Pt/ ZTA catalysts due to the excellent textural,structural,surface acidity and thermal stability.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
基金Financial support from the Spanish Ministry of Science,Innovation and Universities(MCIN/AEI/http://gffzzd3cc09b8251d45dfsqwbxpvqkk9pq66fx.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financially supported by the National Natural Science Foundation of China(Nos.52164029,52074099 and 52464033)Natural Science Foundation of Hainan Province(Nos.221RC585,821MS0782,221MS048 and 221RC 1072)+1 种基金Hainan Province Science and Technology Special Fund(Nos.ZDYF2022GXJS004 and ZDYF2021GXJS028)Scientific Research Foundation of Hainan Tropical Ocean University(No.RHDRC202112)
摘要One prominent cathode material utilized in commercial sodium-ion batteries is the O3-type NaNi0.5Mn0.5O2.The application of this material is hindered by multistage phase transitions and insufficient air stability.In this study,an innovative O3-type NaNi0.5Mn0.5O2,derived from Ni-MOFs (referred to as M-NNMO),has been developed as a cathode material for sodium-ion batteries.The M-NNMO cathode exhibits a discharge specific capacity of 124 mAh·g-1at a rate of0.1C within 2.0 to 4.0 V.Furthermore,this material demonstrates an impressive capacity retention of 75%after undergoing 100 cycles.Complex phase transitions can be inhibited and ion diffusion rates can be increased simultaneously by Ni-MOFs through the enhancement of transition metal-oxygen bonding and the rise n Na layer gap,which are in charge of the remarkable performance improvement.Importantly,the enhanced stability of the M-NNMO transition metal layer based on the uniquestructural properties of Ni-MOFs in air stability tests.This work will provide theoretical guidance to design sodiumion battery cathode materials with superior performance.
基金Project(B14034)supported by the National 111 Project,ChinaProject(2015CX005)supported by the Innovation Driven Plan of Central South University,ChinaProject(2016zzts104)supported by the Fundamental Research Funds for the Central Universities,China
摘要In order to produceα-calcium sulfate hemihydrate(α-CaSO4·0.5H2O)whiskers with high aspect ratios,a minor amount of CuCl2·2H2O was used as the modifying agent in the process of hydrothermal treatment of calcium sulfate dihydrate(CaSO4·2H2O)precursor.The presence of 2.60×10–3 mol/L CuCl2·2H2O resulted in the increase of the aspect ratios ofα-CaSO4·0.5H2O whiskers from 81 to 253.The preferential adsorption of Cu2+on the negative{110}and{100}facets ofα-CaSO4·0.5H2O crystal structures was confirmed by EDS and XPS.And ATR-FTIR demonstrated the ligand adsorption of Cu2+on the surface ofα-CaSO4·0.5H2O whiskers.The experimental results reveal that the whiskers with high aspect ratios are attributed to the adsorption of Cu2+,which promotes the 1-D growth ofα-CaSO4·0.5H2O whiskers along the c axis.
摘要Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption,XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Zr0.5Ti0.5Al0.5O2 catalysts was evaluated using the simulated gases. The results show that ZTA samples exhibit higher specific surface area,larger pore volume and proper surface acidic amount and acidity in comparison with ZT. The results of the catalytic test indicate that Pt/ZT and Pt/ZTA catalysts exhibit excellent low-temperature catalytic activity and lower light-off temperatures of hydrocarbon,carbon monoxide and nitrogen oxides,especially better conversion for nitrogen oxides (NOx). The addition of Al2O3 into ZT enhanced the anti-aging property of Pt/ ZTA catalysts due to the excellent textural,structural,surface acidity and thermal stability.
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.