As a fundamental thermodynamic variable, pressure can alter the bonding patterns and drive phase transitions leading to the creation of new high-pressure phases with exotic properties that are inaccessible at ambient ...As a fundamental thermodynamic variable, pressure can alter the bonding patterns and drive phase transitions leading to the creation of new high-pressure phases with exotic properties that are inaccessible at ambient pressure. Using the swarm intelligence structural prediction method, the phase transition of TiF_(3), from R-3c to the Pnma phase, was predicted at high pressure, accompanied by the destruction of TiF_6 octahedra and formation of TiF_8 square antiprismatic units. The Pnma phase of TiF_(3), formed using the laser-heated diamond-anvil-cell technique was confirmed via high-pressure x-ray diffraction experiments. Furthermore, the in situ electrical measurements indicate that the newly found Pnma phase has a semiconducting character, which is also consistent with the electronic band structure calculations. Finally, it was shown that this pressure-induced phase transition is a general phenomenon in ScF_(3), VF_(3), CrF_(3), and MnF_(3), offering valuable insights into the high-pressure phases of transition metal trifluorides.展开更多
The nanocrystallization behaviour of a bulk Zr-based metallic glass subjected to compressive stress is investigated in the supercooled liquid region. Compared with annealing treatments without compressive stress, comp...The nanocrystallization behaviour of a bulk Zr-based metallic glass subjected to compressive stress is investigated in the supercooled liquid region. Compared with annealing treatments without compressive stress, compressive deformation promotes the development of nucleation and suppresses the coarsening of nanocrystallites at high temperatures.展开更多
P2-type layered oxide,Na2/3Ni1/3Mn2/3O2,has drawn particular interest as a promising cathode material for sodium-ion batteries(SIBs)due to its fast sodium-ion transport channels with low migration potential.However,so...P2-type layered oxide,Na2/3Ni1/3Mn2/3O2,has drawn particular interest as a promising cathode material for sodium-ion batteries(SIBs)due to its fast sodium-ion transport channels with low migration potential.However,some catastrophic flaws,such as air instability,complicated multiphase evolution,and irreversible anionic redox,limit its electrochemical performance and hinder its application.Here,an air-stable single-crystal P2-type Na_(2/3)Ni_(1/3)Mn_(1/3)Ti_(1/3)O_(2)is proposed based on the multifunctional structural modulation of Ti substitution that could alleviate the issues for practical SIBs.As a result,the cathode with high energy density shows excellent air stability and highly reversible phase transitions(P2–OP4),and delivers faster kinetics and stable anion redox chemistry.Meanwhile,a thorough investigation of the relationship between structure,function,and properties is demonstrated,emphasizing formation processes,electrochemical behavior,structural evolution,and air stability.Overall,this study provides the direction of multifunctional structural modulation for the development of high-performance sodium-based layered cathode materials for practical applications.展开更多
采用非等温差示扫描量热法研究纳米铝粉、纳米硼粉和纳米硅粉对六硝基六氮杂异伍兹烷(ε-CL-20)晶型转变的影响。通过测定3种纳米可燃剂与ε-CL-20混合物体系的晶型转变峰值温度,分别采用Kissinger法和Ozawa法计算其转晶反应的活化能和...采用非等温差示扫描量热法研究纳米铝粉、纳米硼粉和纳米硅粉对六硝基六氮杂异伍兹烷(ε-CL-20)晶型转变的影响。通过测定3种纳米可燃剂与ε-CL-20混合物体系的晶型转变峰值温度,分别采用Kissinger法和Ozawa法计算其转晶反应的活化能和指前因子,并根据Friedman无模型等转化率法得到的表观活化能随转化率的变化曲线分析得到其转晶机理。研究结果表明,加入纳米铝、硼和硅粉后,ε-CL-20的转晶反应峰值温度升高,活化能从253 k J/mol分别增大到1 259 k J/mol、571 k J/mol和978 k J/mol,纳米铝粉、硼粉和硅粉可以对ε-CL-20的转晶反应起到抑制作用,纳米硼改变了ε-CL-20的转晶反应机理。展开更多
Molecular ferroelastics with the natural features of mechanical flexibility and switchable spontaneous strain have attracted widespread attention in the scientific community due to their potential applications in tuna...Molecular ferroelastics with the natural features of mechanical flexibility and switchable spontaneous strain have attracted widespread attention in the scientific community due to their potential applications in tunable gratings,flexible memorizers,strain sensors,and intelligent actuators.However,most designs of molecular ferroelastics remain in the stage of blind exploration,posing a challenge to achieve a functional ferroelastic more effectively.Herein,we have successfully obtained a molecular ferroelastic,[Me_(2)NH(CH_(2))_(2)NH_(3)](ReO_(4))_(2)(Me_(2)NH(CH_(2))_(2)NH_(3)=N,N-dimethylethylenediammonium),under the guidance of the mono-/double-protonation strategy.The_double-protonated[Me_(2)NH(CH_(2))_(2)NH_(3)](ReO_(4))_(2) undergoes a paraelastic-ferroelastic phase transition with the Aizu notation of 2/mFi at 322 K.Meanwhile,the theoretical calculation and experimental measurement simultaneously show that[Me_(2)NH(CH_(2))_(2)NH_(3)](ReO_(4))_(2) possesses good mechanical flexibility,because its elastic modulus(E)of 8.26 GPa and hardness(H)of 0.45 GPa are smaller than the average values of organic crystals(E of 12.05 GPa and H of 0.5 GPa),which makes it promising to apply in wearable pressure sensors,implantable medical sensors,high-precision tuners,etc.This work further enriches the molecular ferroelastic family and demonstrates that mono-/double-protonation is one of the effective molecular modification strategies for designing ferroelastics.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12034009, 91961204, and 11974134)。
文摘As a fundamental thermodynamic variable, pressure can alter the bonding patterns and drive phase transitions leading to the creation of new high-pressure phases with exotic properties that are inaccessible at ambient pressure. Using the swarm intelligence structural prediction method, the phase transition of TiF_(3), from R-3c to the Pnma phase, was predicted at high pressure, accompanied by the destruction of TiF_6 octahedra and formation of TiF_8 square antiprismatic units. The Pnma phase of TiF_(3), formed using the laser-heated diamond-anvil-cell technique was confirmed via high-pressure x-ray diffraction experiments. Furthermore, the in situ electrical measurements indicate that the newly found Pnma phase has a semiconducting character, which is also consistent with the electronic band structure calculations. Finally, it was shown that this pressure-induced phase transition is a general phenomenon in ScF_(3), VF_(3), CrF_(3), and MnF_(3), offering valuable insights into the high-pressure phases of transition metal trifluorides.
基金Supported by the Science Foundation for Excellent Young Scholars of Heilongjiang Province under Grant No JC-05-11, the Program for New Century Excellent Talents in University of China under Grant No NCET-04-0322, and the Specialized Research Fund for the Doctoral Programme of Higher Education of China under Grant No 20040213049）
文摘The nanocrystallization behaviour of a bulk Zr-based metallic glass subjected to compressive stress is investigated in the supercooled liquid region. Compared with annealing treatments without compressive stress, compressive deformation promotes the development of nucleation and suppresses the coarsening of nanocrystallites at high temperatures.
基金supported by the National Natural Science Foundation of China(52250710680,51971124,52171217,52202284)Hunan Provincial Science and Technology Innovation Major Project(2020GK1010-2020GK1014-4)+7 种基金Zhejiang Provincial Natural Science Foundation(LZ21E010001,LQ23E020002)Science and Technology Project of State Grid Corporation of China(5419-202158503A-0-5-ZN)Wenzhou key scientific and technological innovation research projects(ZG2023053)Wenzhou Natural Science Foundation(ZG2022032,G20220019,G20220021)Cooperation between industry and education project of Ministry of Education(220601318235513)State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University(EIPE22208)the China Scholarship Council(202106370062)Doctoral Innovation Foundation of Wenzhou University(3162023001001)。
文摘P2-type layered oxide,Na2/3Ni1/3Mn2/3O2,has drawn particular interest as a promising cathode material for sodium-ion batteries(SIBs)due to its fast sodium-ion transport channels with low migration potential.However,some catastrophic flaws,such as air instability,complicated multiphase evolution,and irreversible anionic redox,limit its electrochemical performance and hinder its application.Here,an air-stable single-crystal P2-type Na_(2/3)Ni_(1/3)Mn_(1/3)Ti_(1/3)O_(2)is proposed based on the multifunctional structural modulation of Ti substitution that could alleviate the issues for practical SIBs.As a result,the cathode with high energy density shows excellent air stability and highly reversible phase transitions(P2–OP4),and delivers faster kinetics and stable anion redox chemistry.Meanwhile,a thorough investigation of the relationship between structure,function,and properties is demonstrated,emphasizing formation processes,electrochemical behavior,structural evolution,and air stability.Overall,this study provides the direction of multifunctional structural modulation for the development of high-performance sodium-based layered cathode materials for practical applications.
文摘采用非等温差示扫描量热法研究纳米铝粉、纳米硼粉和纳米硅粉对六硝基六氮杂异伍兹烷(ε-CL-20)晶型转变的影响。通过测定3种纳米可燃剂与ε-CL-20混合物体系的晶型转变峰值温度,分别采用Kissinger法和Ozawa法计算其转晶反应的活化能和指前因子,并根据Friedman无模型等转化率法得到的表观活化能随转化率的变化曲线分析得到其转晶机理。研究结果表明,加入纳米铝、硼和硅粉后,ε-CL-20的转晶反应峰值温度升高,活化能从253 k J/mol分别增大到1 259 k J/mol、571 k J/mol和978 k J/mol,纳米铝粉、硼粉和硅粉可以对ε-CL-20的转晶反应起到抑制作用,纳米硼改变了ε-CL-20的转晶反应机理。
基金financially supported by Southeast University and the National Natural Science Foundation of China(Grant Nos.21991141 and 22371258).
文摘Molecular ferroelastics with the natural features of mechanical flexibility and switchable spontaneous strain have attracted widespread attention in the scientific community due to their potential applications in tunable gratings,flexible memorizers,strain sensors,and intelligent actuators.However,most designs of molecular ferroelastics remain in the stage of blind exploration,posing a challenge to achieve a functional ferroelastic more effectively.Herein,we have successfully obtained a molecular ferroelastic,[Me_(2)NH(CH_(2))_(2)NH_(3)](ReO_(4))_(2)(Me_(2)NH(CH_(2))_(2)NH_(3)=N,N-dimethylethylenediammonium),under the guidance of the mono-/double-protonation strategy.The_double-protonated[Me_(2)NH(CH_(2))_(2)NH_(3)](ReO_(4))_(2) undergoes a paraelastic-ferroelastic phase transition with the Aizu notation of 2/mFi at 322 K.Meanwhile,the theoretical calculation and experimental measurement simultaneously show that[Me_(2)NH(CH_(2))_(2)NH_(3)](ReO_(4))_(2) possesses good mechanical flexibility,because its elastic modulus(E)of 8.26 GPa and hardness(H)of 0.45 GPa are smaller than the average values of organic crystals(E of 12.05 GPa and H of 0.5 GPa),which makes it promising to apply in wearable pressure sensors,implantable medical sensors,high-precision tuners,etc.This work further enriches the molecular ferroelastic family and demonstrates that mono-/double-protonation is one of the effective molecular modification strategies for designing ferroelastics.
