Li-and Mn-rich(LMR)cathode materials have received tremendous attention due to the highly reversible specific capacity(>250 m Ah·g^(-1)).In the analysis of its crystal structure,the two-phase composite model g...Li-and Mn-rich(LMR)cathode materials have received tremendous attention due to the highly reversible specific capacity(>250 m Ah·g^(-1)).In the analysis of its crystal structure,the two-phase composite model gains increasing acceptance,and the phase transition behaviors in LMR cathode materials have been extensively studied.Herein,the structure controversy of LMR cathode materials,and the mechanisms of phase transition are summarized.Particularly,the causes of initiating or accelerating the phase transition of LMR cathode materials have been summarized into three main driving forces,i.e.,the electrochemical driving force,the component driving force and the thermodynamic driving force.Additionally,the applications of phase transition behavior in improving the electrochemical performance of LMR cathode materials,including the construction of spinel surface coating and spinel/layered hetero-structure are discussed.展开更多
The title ammonium compound ethyl 2-（4-aminophenoxy）acetate （C10 H13NO3, I） and its crown ether inclusion complex {[（CIoHI4NO3）·（18-crown-6）]·[PF6] , II} （18-crown-6 = 1,4,7,10,13,16-hexaoxacyclo-oc...The title ammonium compound ethyl 2-（4-aminophenoxy）acetate （C10 H13NO3, I） and its crown ether inclusion complex {[（CIoHI4NO3）·（18-crown-6）]·[PF6] , II} （18-crown-6 = 1,4,7,10,13,16-hexaoxacyclo-octadecane） were synthesized. The ammonium compound I was determined by 11-t NMR, IR and ESI-MS techiniques. X-ray crystal- lography reveals that compound I crystallizes in the triclinic system with space group of P-l, all the atoms in ｜ are almost coplanar except H, and N--H…O hydrogen bonds lead to the formation of one dimensional chain. The ro- tator-stator-like compound 11 was crystallizes in the centrosymmetric monoclinic system with space group of P21/c. The supramolecular was formed via N--H…O hydrogen-bond interactions. Temperature-dependent dielectric constants of compound II were measured.展开更多
A new compound Sr2FeWO6 has been synthesized by solid state sintering. The phase transition of this compound was investigated by means of differential scanning calorimetry (DSC), X-ray powder diffraction, precise meas...A new compound Sr2FeWO6 has been synthesized by solid state sintering. The phase transition of this compound was investigated by means of differential scanning calorimetry (DSC), X-ray powder diffraction, precise measurement of lattice parameters and other methods. It has been discovered that the compound has a displacive phase transition of the first order at (360±5)°. The low temperature phase, α-Sr2FeWO6, belongs to tetragonal crystal system, with space group I4/m; its lattice parameters at room temperature are: a=b=0.55702 nm, and c=0.79094 ran, the measured density is Dm = 6.93 g/cm3, and each unit cell contains two formula weights. The high temperature phase, β-Sr2FeWO6, belongs to the cubic system, with space group Fm3m and the lattice parameter is a=0.7939nm at 400°; z=4. The calculated density is Dx =6.780 g/cm3. The crystal structures of α-Sr2FeWO6 and β-Sr2FeWO6 were also determined by means of the X-ray polycrystal diffraction method. The phase transition mechanism and the temperature are investigated.展开更多
The title compound, tetramethylammonium nickel nitrite [（CH3）4N][Ni（NO2）3], has a hexagonal perovskite-type structure with formula ABX3. It undergoes two reversible phase transitions occurring at about 409.1 and 4...The title compound, tetramethylammonium nickel nitrite [（CH3）4N][Ni（NO2）3], has a hexagonal perovskite-type structure with formula ABX3. It undergoes two reversible phase transitions occurring at about 409.1 and 428.4 K, associated with dielectric transitions. DSC measurement and dielectric measurement confirm the transition. The variable-temperature X-ray structural determinations and the powder X-ray diffraction （PXRD） experiments reveal that this compound has the same space group P3ml （No. 164） at 293 K, 413 K and 438 K. The phase transitions are caused by the rotation of the [（CH3）4N]＋ cation.展开更多
Diamond possesses excellent thermal conductivity and tunable bandgap.Currently,the high-pressure,high-temperature,and chemical vapor deposition methods are the most promising strategies for the commercial-scale produc...Diamond possesses excellent thermal conductivity and tunable bandgap.Currently,the high-pressure,high-temperature,and chemical vapor deposition methods are the most promising strategies for the commercial-scale production of synthetic diamond.Although diamond has been extensively employed in jewelry and cutting/grinding tasks,the realization of its high-end applications through microstructure engineering has long been sought.Herein,we discuss the microstructures encountered in diamond and further concentrate on cutting-edge investigations utilizing electron microscopy techniques to illuminate the transition mechanism between graphite and diamond during the synthesis and device constructions.The impacts of distinct microstructures on the electrical applications of diamond,especially the photoelectrical,electrical,and thermal properties,are elaborated.The recently reported elastic and plastic deformations revealed through in situ microscopy techniques are also summarized.Finally,the limitations,perspectives,and corresponding solutions are proposed.展开更多
分析φ6.5 mm 55SiCr盘条拉拔过程发生抽芯断裂的原因。采用热模拟试验测定断裂试样在不同冷却速度下的相变组织:当冷却速率不超过2℃/s时,其显微组织为索氏体、珠光体、少量铁素体;当冷却速率大于3℃/s时,其显微组织为屈氏体、贝氏体...分析φ6.5 mm 55SiCr盘条拉拔过程发生抽芯断裂的原因。采用热模拟试验测定断裂试样在不同冷却速度下的相变组织:当冷却速率不超过2℃/s时,其显微组织为索氏体、珠光体、少量铁素体;当冷却速率大于3℃/s时,其显微组织为屈氏体、贝氏体、马氏体等异常组织。试验结果表明盘条的异常组织是产生拉拔脆断的主要原因。给出改进措施:(1)对凝固中的钢水进行电磁搅伴,并对最后凝固区附近的一段铸坯进行轻压下来改善铸坯的中心偏析;(2)对轧制控冷程序进行优化,盘条经吐丝风冷进入保温罩前的温度控制在650～700℃。采取以上措施生产的φ6.5 mm 55SiCr盘条,其组织为索氏体、珠光体和少量不连续网状铁素体,经用户使用,未发生断裂现象,可满足用户拉拔生产需要。展开更多
基金the Natural Science Foundation of Fujian Province of China(Nos.2019J06003 and 2020J05014)the National Natural Science Foundation of China(Nos.51931006 and 51871188)+4 种基金the National Key R&D Program of China(No.2016YFA0202602)Guangdong Basic and Applied Basic Research Foundation(Nos.2021A1515010139 and 2019A1515011070)the Science and Technology Planning Projects of Fujian Province,China(No.2020H0005)the Fundamental Research Funds for the Central Universities of China(Nos.20720200068 and 20720190013)the“Double-First Class”Foundation of Materials Intelligent Manufacturing Discipline of Xiamen University。
文摘Li-and Mn-rich(LMR)cathode materials have received tremendous attention due to the highly reversible specific capacity(>250 m Ah·g^(-1)).In the analysis of its crystal structure,the two-phase composite model gains increasing acceptance,and the phase transition behaviors in LMR cathode materials have been extensively studied.Herein,the structure controversy of LMR cathode materials,and the mechanisms of phase transition are summarized.Particularly,the causes of initiating or accelerating the phase transition of LMR cathode materials have been summarized into three main driving forces,i.e.,the electrochemical driving force,the component driving force and the thermodynamic driving force.Additionally,the applications of phase transition behavior in improving the electrochemical performance of LMR cathode materials,including the construction of spinel surface coating and spinel/layered hetero-structure are discussed.
文摘The title ammonium compound ethyl 2-（4-aminophenoxy）acetate （C10 H13NO3, I） and its crown ether inclusion complex {[（CIoHI4NO3）·（18-crown-6）]·[PF6] , II} （18-crown-6 = 1,4,7,10,13,16-hexaoxacyclo-octadecane） were synthesized. The ammonium compound I was determined by 11-t NMR, IR and ESI-MS techiniques. X-ray crystal- lography reveals that compound I crystallizes in the triclinic system with space group of P-l, all the atoms in ｜ are almost coplanar except H, and N--H…O hydrogen bonds lead to the formation of one dimensional chain. The ro- tator-stator-like compound 11 was crystallizes in the centrosymmetric monoclinic system with space group of P21/c. The supramolecular was formed via N--H…O hydrogen-bond interactions. Temperature-dependent dielectric constants of compound II were measured.
文摘A new compound Sr2FeWO6 has been synthesized by solid state sintering. The phase transition of this compound was investigated by means of differential scanning calorimetry (DSC), X-ray powder diffraction, precise measurement of lattice parameters and other methods. It has been discovered that the compound has a displacive phase transition of the first order at (360±5)°. The low temperature phase, α-Sr2FeWO6, belongs to tetragonal crystal system, with space group I4/m; its lattice parameters at room temperature are: a=b=0.55702 nm, and c=0.79094 ran, the measured density is Dm = 6.93 g/cm3, and each unit cell contains two formula weights. The high temperature phase, β-Sr2FeWO6, belongs to the cubic system, with space group Fm3m and the lattice parameter is a=0.7939nm at 400°; z=4. The calculated density is Dx =6.780 g/cm3. The crystal structures of α-Sr2FeWO6 and β-Sr2FeWO6 were also determined by means of the X-ray polycrystal diffraction method. The phase transition mechanism and the temperature are investigated.
基金supported by the Project 973(No. 2014CB848800)National Natural Science Foundation of China (Nos.91022003 and 21301029)+1 种基金Jiangsu Province NSF(No. BK20130600)Program for NCET and Ph.D.Programs Foundation of Ministry of Education of China(No.20130092120013)
文摘The title compound, tetramethylammonium nickel nitrite [（CH3）4N][Ni（NO2）3], has a hexagonal perovskite-type structure with formula ABX3. It undergoes two reversible phase transitions occurring at about 409.1 and 428.4 K, associated with dielectric transitions. DSC measurement and dielectric measurement confirm the transition. The variable-temperature X-ray structural determinations and the powder X-ray diffraction （PXRD） experiments reveal that this compound has the same space group P3ml （No. 164） at 293 K, 413 K and 438 K. The phase transitions are caused by the rotation of the [（CH3）4N]＋ cation.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFB3608604)National Natural Science Foundation of China (Grant Nos.12274371,52072345,62271450,U21A2070,and 62027816)+1 种基金Natural Science Foundation of Henan Province (Grant Nos.222300420077,222301420037)Foundation for the Returned Overseas Researchers of Henan Province.
文摘Diamond possesses excellent thermal conductivity and tunable bandgap.Currently,the high-pressure,high-temperature,and chemical vapor deposition methods are the most promising strategies for the commercial-scale production of synthetic diamond.Although diamond has been extensively employed in jewelry and cutting/grinding tasks,the realization of its high-end applications through microstructure engineering has long been sought.Herein,we discuss the microstructures encountered in diamond and further concentrate on cutting-edge investigations utilizing electron microscopy techniques to illuminate the transition mechanism between graphite and diamond during the synthesis and device constructions.The impacts of distinct microstructures on the electrical applications of diamond,especially the photoelectrical,electrical,and thermal properties,are elaborated.The recently reported elastic and plastic deformations revealed through in situ microscopy techniques are also summarized.Finally,the limitations,perspectives,and corresponding solutions are proposed.
文摘分析φ6.5 mm 55SiCr盘条拉拔过程发生抽芯断裂的原因。采用热模拟试验测定断裂试样在不同冷却速度下的相变组织:当冷却速率不超过2℃/s时,其显微组织为索氏体、珠光体、少量铁素体;当冷却速率大于3℃/s时,其显微组织为屈氏体、贝氏体、马氏体等异常组织。试验结果表明盘条的异常组织是产生拉拔脆断的主要原因。给出改进措施:(1)对凝固中的钢水进行电磁搅伴,并对最后凝固区附近的一段铸坯进行轻压下来改善铸坯的中心偏析;(2)对轧制控冷程序进行优化,盘条经吐丝风冷进入保温罩前的温度控制在650～700℃。采取以上措施生产的φ6.5 mm 55SiCr盘条,其组织为索氏体、珠光体和少量不连续网状铁素体,经用户使用,未发生断裂现象,可满足用户拉拔生产需要。
