Ceramics compound Ti_(3)AlC_(2) exhibits nano-layered structure and has the properties of both ceramic and metal.It includes easy machinability,good high-temperature resistance and irradiation–damage tolerance.So it...Ceramics compound Ti_(3)AlC_(2) exhibits nano-layered structure and has the properties of both ceramic and metal.It includes easy machinability,good high-temperature resistance and irradiation–damage tolerance.So it’s supposed to be a candidate for future nuclear reactor.For example,it can be used as a coatings on Zr cladding materials.It can withstand severer irradiation damage and prevent the reaction between water and Zr.Therefore the understanding of Ti3AlC2under irradiation is fundamentally important for the development of nuclear materials[1].展开更多
MAX phase material is a layered ternary compound with the chemical formula Mn+1AXn.M represents the transition metal the A represents A-group element and X is the nitrogen or carbon.We take Ti_(3)AlC_(2) as the sample...MAX phase material is a layered ternary compound with the chemical formula Mn+1AXn.M represents the transition metal the A represents A-group element and X is the nitrogen or carbon.We take Ti_(3)AlC_(2) as the sample.This material exhibits a combination of the attributes of both metals and ceramics[1].As a result,it has been considered as potential materials for use in current and future nuclear applications.Numerous researches have been focused on the phase transformation progress and anti-amorphization trait of this material[2,3].However,few researches have reported the behavior of vacancy defects after irradiation.We use the PAT and DBS technique to investigate this issue and try to find the relationship among the density of vacancy type defects,phase transformation,the irradiation fluence and temperature.展开更多
Herein,a novel kind of high-entropy MAX phases,(Mo_(0.25)Cr_(0.25)Ti_(0.25)V_(0.25))_(3)AlC_(2)powders were success-fully synthesized by a newly proposed two-step solid state reaction process.The oxidation experiments...Herein,a novel kind of high-entropy MAX phases,(Mo_(0.25)Cr_(0.25)Ti_(0.25)V_(0.25))_(3)AlC_(2)powders were success-fully synthesized by a newly proposed two-step solid state reaction process.The oxidation experiments demonstrate that the oxidation products of Al_(2)Mo_(3)O_(12) and rutile TiO 2 are formed at about 600 and 800℃,respectively.Besides,the dielectric and electromagnetic(EM)wave absorption properties of(Mo_(0.25)Cr_(0.25)Ti_(0.25)V_(0.25))_(3)AlC_(2)powders and those after oxidation at different temperatures were also exam-ined.The results show that the as-synthesized(Mo_(0.25)Cr_(0.25)Ti_(0.25)V_(0.25))_(3)AlC_(2)powders possess excellent EM wave absorption performances with the minimum reflection loss(RL)of-45.80 dB(at 1.7 mm thickness)and the maximum effective absorption bandwidth(E AB)of 3.6 GHz(at 1.5 mm thickness).After oxidation at 400-800℃,due to the coupling of conductivity loss and polarization loss,(Mo_(0.25)Cr_(0.25)Ti_(0.25)V_(0.25))_(3)AlC_(2)powders can retain good EM wave absorption properties in a certain frequency range.In this paper,the effects of oxidation on EM wave absorption properties of high-entropy MAX phases were systematically investigated for the first time.This work manifests that high-entropy MAX phases are promising EM wave absorbing candidates and can maintain good EM wave absorption performances after oxidation.展开更多
Defect-rich,highly porous two-dimensional carbon nanosheets(CNS) have attracted tremendous research interests in catalysis and environmental purification and other fields,because of their unique micromorphology,chemic...Defect-rich,highly porous two-dimensional carbon nanosheets(CNS) have attracted tremendous research interests in catalysis and environmental purification and other fields,because of their unique micromorphology,chemical stability and high specific surface area.Herein,in this work,we report a new solution to synthesize an ultrathin two-dimensional CNS with rich defects and abundant pores via two-step etching the Ti_(3)AlC_(2)with the help of I2and NaOH.The CNS thickness,specific surface area and pore volume could be all tunable by adding the amount of I2.And the highest specific surface area and pore volume of the synthesized 2D CNS can be achieved 1134.4 m^(2)/g and 0.80 cm^(3)/g,with a thickness of only 0.64 nm and a yield of 35.9%.When employed as the anodes for lithium-ion batteries,the synthesized CNS anodes exhibit good cycling and rate capabilities.This work provides a novel and facile strategy for synthesizing highly porous and defective 2D carbon materials with good lithium storage properties.展开更多
锂离子电容器(LICs)是一种很有前途的储能装置,因为它们同时具有锂离子电池的高能量密度和超级电容器的高功率密度的特点.然而,由于锂离子电容器中阳极和阴极之间电化学反应动力学的不匹配使得探索具有快速离子扩散和电子转移通道的阳...锂离子电容器(LICs)是一种很有前途的储能装置,因为它们同时具有锂离子电池的高能量密度和超级电容器的高功率密度的特点.然而,由于锂离子电容器中阳极和阴极之间电化学反应动力学的不匹配使得探索具有快速离子扩散和电子转移通道的阳极材料面临挑战.在此,通过静电纺丝策略将具有可控末端基团的二维Ti_(3)C_(2)MXene引入一维碳纳米纤维中,形成三维导电网络.在这种Ti_(3)C_(2)MXene和碳基复合材料(称为KTi-400@CNFs)中,二维纳米片结构赋予了Ti_(3)C_(2)MXene更多Li+存储活性位点,而碳骨架则有利于提高复合材料的导电性.更值得一提的是,在Ti_(3)C_(2)MXene和碳骨架的界面上形成了Ti–O–C键.复合材料中的这种化学键为电子的快速传输和离子在层与层之间纵向的快速扩散建立了桥梁.因此,优化后的KTi-400@CNFs复合材料在电流密度为5 A g-1的情况下,500次循环后仍保持235 mA h g-1的良好容量.由KTi-400@CNFs//AC组成的锂离子电容器实现了高能量密度(114.3 W h kg-1)和高功率密度(12.8 kW kg-1).KTi-400@CNFs的这种独特结构和优异的电化学性能为二维材料制备提供了参考.展开更多
Na superionic conductor(NASICON)-type La_(0.33)Ti_(2)(PO_(4))_(3)(LaTP) is firstly proposed as sodium/potassium storage materials.The density functional theory(DFT) calculations show that LaTP has good electronic char...Na superionic conductor(NASICON)-type La_(0.33)Ti_(2)(PO_(4))_(3)(LaTP) is firstly proposed as sodium/potassium storage materials.The density functional theory(DFT) calculations show that LaTP has good electronic character and low Na^(+)/K^(+)migration barriers.The flexible La_(0.33)Ti_(2)(PO_(4))_(3)/C nanofiber film is synthesized via electrostatic spinning and investigated as free-standing electrode applied to sodium-ion batteries(SIBs) and potassiumion batteries(PIBs) in this work.The low band gap and Na^(+)/K^(+) migration barriers of LaTP,unique morphology,and complete conductive carbon net allow the La_(0.33)Ti_(2)(PO_(4))_(3)/C nanofibers film to deliver high capacity(296.3 mAh·g^(-1) for SIBs and 235.8 mAh·g^(-1) for PIBs),excellent rate performance(142.5 mAh·g^(-1) for SIBs and50.5 mAh·g^(-1) for PIBs at 1.00 A·g^(-1)),and superior cyclability above 1000 cycles.The full-cell tests show that the material has a good application prospect,indicating a promising flexible anode material for SIBs and PIBs.展开更多
This paper investigated the corrosion behaviors of Ti_(3)AlC_(2) at 700℃in molten KOH with various mass ratios.If the mass ratio of KOH:Ti_(3)AlC_(2)≤2,Ti_(3)AlC_(2) can resist KOH hot corrosion in 2 h.Ti_(3)AlC_(2)...This paper investigated the corrosion behaviors of Ti_(3)AlC_(2) at 700℃in molten KOH with various mass ratios.If the mass ratio of KOH:Ti_(3)AlC_(2)≤2,Ti_(3)AlC_(2) can resist KOH hot corrosion in 2 h.Ti_(3)AlC_(2) suffered serious corrosion attack if the mass ratio≥3.The main compositions of corroded samples were amorphous graphite and potassium titanates(K_(2)O·nTiO_(2)).If the samples were washed by acid and dried,potassium titanates could decompose to K_(2)O and amorphous rutile.Based on the experimental results,a corrosion mechanism of Ti_(3)AlC_(2) in molten KOH was proposed.展开更多
文摘Ceramics compound Ti_(3)AlC_(2) exhibits nano-layered structure and has the properties of both ceramic and metal.It includes easy machinability,good high-temperature resistance and irradiation–damage tolerance.So it’s supposed to be a candidate for future nuclear reactor.For example,it can be used as a coatings on Zr cladding materials.It can withstand severer irradiation damage and prevent the reaction between water and Zr.Therefore the understanding of Ti3AlC2under irradiation is fundamentally important for the development of nuclear materials[1].
文摘MAX phase material is a layered ternary compound with the chemical formula Mn+1AXn.M represents the transition metal the A represents A-group element and X is the nitrogen or carbon.We take Ti_(3)AlC_(2) as the sample.This material exhibits a combination of the attributes of both metals and ceramics[1].As a result,it has been considered as potential materials for use in current and future nuclear applications.Numerous researches have been focused on the phase transformation progress and anti-amorphization trait of this material[2,3].However,few researches have reported the behavior of vacancy defects after irradiation.We use the PAT and DBS technique to investigate this issue and try to find the relationship among the density of vacancy type defects,phase transformation,the irradiation fluence and temperature.
基金This work was financially supported by the Major Basic Re-search Projects of Shandong Natural Science Foundation(No.ZR2018ZB0104)the Science and Technology Development Project of Shandong Province(Nos.2016GGX102003,2017GGX20105)the Natural Science Foundation of Shandong Province(No.ZR2017BEM032).
文摘Herein,a novel kind of high-entropy MAX phases,(Mo_(0.25)Cr_(0.25)Ti_(0.25)V_(0.25))_(3)AlC_(2)powders were success-fully synthesized by a newly proposed two-step solid state reaction process.The oxidation experiments demonstrate that the oxidation products of Al_(2)Mo_(3)O_(12) and rutile TiO 2 are formed at about 600 and 800℃,respectively.Besides,the dielectric and electromagnetic(EM)wave absorption properties of(Mo_(0.25)Cr_(0.25)Ti_(0.25)V_(0.25))_(3)AlC_(2)powders and those after oxidation at different temperatures were also exam-ined.The results show that the as-synthesized(Mo_(0.25)Cr_(0.25)Ti_(0.25)V_(0.25))_(3)AlC_(2)powders possess excellent EM wave absorption performances with the minimum reflection loss(RL)of-45.80 dB(at 1.7 mm thickness)and the maximum effective absorption bandwidth(E AB)of 3.6 GHz(at 1.5 mm thickness).After oxidation at 400-800℃,due to the coupling of conductivity loss and polarization loss,(Mo_(0.25)Cr_(0.25)Ti_(0.25)V_(0.25))_(3)AlC_(2)powders can retain good EM wave absorption properties in a certain frequency range.In this paper,the effects of oxidation on EM wave absorption properties of high-entropy MAX phases were systematically investigated for the first time.This work manifests that high-entropy MAX phases are promising EM wave absorbing candidates and can maintain good EM wave absorption performances after oxidation.
基金financially supported by the National Natural Science Foundation of China (No. 51902036)Natural Science Foundation of Chongqing Science & Technology Commission (No. cstc2019jcyj-msxm1407)+4 种基金Natural Science Foundation of Jiangsu Province (No. BK20200047)Natural Science Foundation of Chongqing Technology and Business University (No. 1952009)the Science and Technology Research Program of Chongqing Education Commission (Nos. KJQN201900826 and KJQN201800808)the Venture & Innovation Support Program for Chongqing Overseas Returnees (Nos. CX2021046 and CX2018129)the Innovation Group of New Technologies for Industrial Pollution Control of Chongqing Education Commission (No. CXQT19023)。
文摘Defect-rich,highly porous two-dimensional carbon nanosheets(CNS) have attracted tremendous research interests in catalysis and environmental purification and other fields,because of their unique micromorphology,chemical stability and high specific surface area.Herein,in this work,we report a new solution to synthesize an ultrathin two-dimensional CNS with rich defects and abundant pores via two-step etching the Ti_(3)AlC_(2)with the help of I2and NaOH.The CNS thickness,specific surface area and pore volume could be all tunable by adding the amount of I2.And the highest specific surface area and pore volume of the synthesized 2D CNS can be achieved 1134.4 m^(2)/g and 0.80 cm^(3)/g,with a thickness of only 0.64 nm and a yield of 35.9%.When employed as the anodes for lithium-ion batteries,the synthesized CNS anodes exhibit good cycling and rate capabilities.This work provides a novel and facile strategy for synthesizing highly porous and defective 2D carbon materials with good lithium storage properties.
基金supported by the National Natural Science Foundation of China (22005167 and 21905152)Shandong Provincial Natural Science Foundation (ZR2020QB125 and ZR2020MB045)+2 种基金China Postdoctoral Science Foundation (2021M693256, 2021T140687 and 2022M713249)Qingdao Postdoctoral Applied Research Project, Taishan Scholar Project of Shandong Province (ts20190937)the Youth Innovation Team Project for Talent Introduction and Cultivation in Universities of Shandong Province。
文摘锂离子电容器(LICs)是一种很有前途的储能装置,因为它们同时具有锂离子电池的高能量密度和超级电容器的高功率密度的特点.然而,由于锂离子电容器中阳极和阴极之间电化学反应动力学的不匹配使得探索具有快速离子扩散和电子转移通道的阳极材料面临挑战.在此,通过静电纺丝策略将具有可控末端基团的二维Ti_(3)C_(2)MXene引入一维碳纳米纤维中,形成三维导电网络.在这种Ti_(3)C_(2)MXene和碳基复合材料(称为KTi-400@CNFs)中,二维纳米片结构赋予了Ti_(3)C_(2)MXene更多Li+存储活性位点,而碳骨架则有利于提高复合材料的导电性.更值得一提的是,在Ti_(3)C_(2)MXene和碳骨架的界面上形成了Ti–O–C键.复合材料中的这种化学键为电子的快速传输和离子在层与层之间纵向的快速扩散建立了桥梁.因此,优化后的KTi-400@CNFs复合材料在电流密度为5 A g-1的情况下,500次循环后仍保持235 mA h g-1的良好容量.由KTi-400@CNFs//AC组成的锂离子电容器实现了高能量密度(114.3 W h kg-1)和高功率密度(12.8 kW kg-1).KTi-400@CNFs的这种独特结构和优异的电化学性能为二维材料制备提供了参考.
基金financially supported by the National Natural Science Foundation of China (No. 52072325)the Key Research Foundation of Education Bureau of Hunan Province, China (No. 20A486)+2 种基金Hunan 2011 Collaborative Innovation Center of Chemical Engineering and Technology with Environmental Benignity and Effective Resource Utilization, Program for Innovative Research Cultivation Team in University of Ministry of Education of China (No. 1337304)the 111 Project (No. B12015)the Natural Science Foundation of Shandong Province (No. ZR2020MB045)。
文摘Na superionic conductor(NASICON)-type La_(0.33)Ti_(2)(PO_(4))_(3)(LaTP) is firstly proposed as sodium/potassium storage materials.The density functional theory(DFT) calculations show that LaTP has good electronic character and low Na^(+)/K^(+)migration barriers.The flexible La_(0.33)Ti_(2)(PO_(4))_(3)/C nanofiber film is synthesized via electrostatic spinning and investigated as free-standing electrode applied to sodium-ion batteries(SIBs) and potassiumion batteries(PIBs) in this work.The low band gap and Na^(+)/K^(+) migration barriers of LaTP,unique morphology,and complete conductive carbon net allow the La_(0.33)Ti_(2)(PO_(4))_(3)/C nanofibers film to deliver high capacity(296.3 mAh·g^(-1) for SIBs and 235.8 mAh·g^(-1) for PIBs),excellent rate performance(142.5 mAh·g^(-1) for SIBs and50.5 mAh·g^(-1) for PIBs at 1.00 A·g^(-1)),and superior cyclability above 1000 cycles.The full-cell tests show that the material has a good application prospect,indicating a promising flexible anode material for SIBs and PIBs.
基金This work was supported by the National Nature Science Foundation of China(Grant Nos.51002045,51205111)Program for Innovative Research Team of Henan Polytechnic University(T2013-4)Opening Project of Henan Key Discipline Open Laboratory of Mining Engineering Materials(MEM12-5).
文摘This paper investigated the corrosion behaviors of Ti_(3)AlC_(2) at 700℃in molten KOH with various mass ratios.If the mass ratio of KOH:Ti_(3)AlC_(2)≤2,Ti_(3)AlC_(2) can resist KOH hot corrosion in 2 h.Ti_(3)AlC_(2) suffered serious corrosion attack if the mass ratio≥3.The main compositions of corroded samples were amorphous graphite and potassium titanates(K_(2)O·nTiO_(2)).If the samples were washed by acid and dried,potassium titanates could decompose to K_(2)O and amorphous rutile.Based on the experimental results,a corrosion mechanism of Ti_(3)AlC_(2) in molten KOH was proposed.
