The microstructural characteristic of the misfit-layered compound PbTiS3 has been studied with transmission electron microscopy. All the incommensurate modulation-induced satellite spots and main diffraction spots of ...The microstructural characteristic of the misfit-layered compound PbTiS3 has been studied with transmission electron microscopy. All the incommensurate modulation-induced satellite spots and main diffraction spots of basic sublattices can be indexed systematically with a superspace group method. Finally, the relationship between the electronic transport properties and the crystal structure is discussed.展开更多
Significant two-way shape memory effect(TWSME)was achieved in single crystals of single-phase multielement Ni42-x Cu8 Cox Mn37 Ga13(8≤x≤12)alloys by performing thermomechanical training.However,anomalous dependence ...Significant two-way shape memory effect(TWSME)was achieved in single crystals of single-phase multielement Ni42-x Cu8 Cox Mn37 Ga13(8≤x≤12)alloys by performing thermomechanical training.However,anomalous dependence of the martensitic transformation temperature span on Co content was observed.Before training,quite a narrow temperature span of the martensitic transformation,nearly independent of the Co content,was observed in all single crystals.After training the temperature span was still narrow for 8≤x≤10.9 but was obviously expanded for 10.9<x≤12.High-resolution transmission electron microscopy revealed that at the atomic scale,there exists incommensurate modulated structure in the single phase single crystals,as evidenced by nonperiodic satellite spots in the selected area electronic diffraction patterns.Moreover,the modulated wave vector of the satellite spots was increased by higher Co contents.Combining first principal calculations it was considered that the incommensurate modulated structure originates from the formation of Co-Co pairs.After training arrays of ordered dislocations with the same Burgers vector were introduced for 8≤x≤10.9 but the network of dislocations was formed for 10.9<x≤12.Based on analysis of transmission electron microscopy,geometric phase,thermodynamics,and Landau theory,it was considered that the austenite/martensite phase interface was pinned by the network of dislocations,expanding the temperature span of the martensitic transformation.This work supplies new insights for understanding the microstructure and martensitic transformation of Ni-Mn-Ga-based alloys.展开更多
The study of temperature-driven phase transitions is significant in phosphate chemistry,as these transitions often lead to unique physical properties for specific applications,such as catalysis,energy storage,ion cond...The study of temperature-driven phase transitions is significant in phosphate chemistry,as these transitions often lead to unique physical properties for specific applications,such as catalysis,energy storage,ion conduction,and nonlinear optics[1–3].The phase transition from room temperature(RT)to high temperature(HT)in phosphates is always from periodic structures to disordered or amorphous states[4–8].At RT,phosphates often maintain a highly ordered crystalline structure,which is stabilized by the lower thermal energy.As the temperature increases,the thermal energy disrupts the periodic arrangement of atoms and leads to a phase transition,where the once ordered structure becomes increasingly disordered or even amorphous.展开更多
A series of tungsten bronze(Sr_(2-x)Bi_(x)Ag_(0.2)Na_(0.8))(Nb_(4.8-x)Zr_(x)Sb_(0.2))O15 compounds were fabricated by solidstate method to systematically study the impacts of co-doping Bi^(3+)/Zr^(4+)ions in A/B-sites...A series of tungsten bronze(Sr_(2-x)Bi_(x)Ag_(0.2)Na_(0.8))(Nb_(4.8-x)Zr_(x)Sb_(0.2))O15 compounds were fabricated by solidstate method to systematically study the impacts of co-doping Bi^(3+)/Zr^(4+)ions in A/B-sites on the structures,relaxor characteristics,and energy-storage performances.The relationship between structures and relaxor behaviors are summarized as three main points:(1)with increasing the amount of codoping Bi^(3+)/Zr^(4+)ions,the crystal structure evolved from an orthorhombic Bbm^(2) to a tetragonal paraelectric P4/mbm symmetry at room temperature;(2)enhancing relaxor characteristics at room temperature was achieved by tailoring the temperature region of T_(m)-T_(B)(T_(m) is the dielectric maximum temperature,T_(B) is the Burns temperature),which could be attributed to the incommensurate local structure modulations associated with the orthogonal distortion of P4bm symmetry and the appearance of microdomains;(3)The co-introduction of Bi^(3+)and Zr^(4+)could also played an important role in inhibiting the grain sizes,increasing resistivity and band-gap to enhance the breakdown strength.Finally,a superior recoverable energy-storage density(3.61 J/cm^(3))and an ultrahigh energy efficiency(90%)were obtained simultaneously at 389 kV/cm in BZ0.05 ceramics.Moreover,an outstanding power density(158.98 MW/cm^(3))together with a current density of 1422.29 A/cm^(2)was realized at 220 kV/cm from the charging-discharging performance measurements.The excellent energy-storage performance(ESPs)make the environmentally friendly BZ0.05 samples show enormous potential in high-power capacitor applications.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2012CB932302)the National Natural Science Foundation of China(Grant No.50921091)the Specific Funding of the Discipline and Graduate Education Project of Beijing Municipal Commission of Education,China
文摘The microstructural characteristic of the misfit-layered compound PbTiS3 has been studied with transmission electron microscopy. All the incommensurate modulation-induced satellite spots and main diffraction spots of basic sublattices can be indexed systematically with a superspace group method. Finally, the relationship between the electronic transport properties and the crystal structure is discussed.
基金support from the National Key Research and Development Program of China(Grant No.2021YFB3501402)the National Natural Science Foundation of China(Grant Nos.52250313 and 52121001)Yang Liu and Chen Si acknowledge financial support from the National Natural Science Foundation of China(Grant No.12274013).
文摘Significant two-way shape memory effect(TWSME)was achieved in single crystals of single-phase multielement Ni42-x Cu8 Cox Mn37 Ga13(8≤x≤12)alloys by performing thermomechanical training.However,anomalous dependence of the martensitic transformation temperature span on Co content was observed.Before training,quite a narrow temperature span of the martensitic transformation,nearly independent of the Co content,was observed in all single crystals.After training the temperature span was still narrow for 8≤x≤10.9 but was obviously expanded for 10.9<x≤12.High-resolution transmission electron microscopy revealed that at the atomic scale,there exists incommensurate modulated structure in the single phase single crystals,as evidenced by nonperiodic satellite spots in the selected area electronic diffraction patterns.Moreover,the modulated wave vector of the satellite spots was increased by higher Co contents.Combining first principal calculations it was considered that the incommensurate modulated structure originates from the formation of Co-Co pairs.After training arrays of ordered dislocations with the same Burgers vector were introduced for 8≤x≤10.9 but the network of dislocations was formed for 10.9<x≤12.Based on analysis of transmission electron microscopy,geometric phase,thermodynamics,and Landau theory,it was considered that the austenite/martensite phase interface was pinned by the network of dislocations,expanding the temperature span of the martensitic transformation.This work supplies new insights for understanding the microstructure and martensitic transformation of Ni-Mn-Ga-based alloys.
基金supported by the National Natural Science Foundation of China(22105218)Science and Technology Project of Jiangxi Provincial Education Department(GJJ2201525).
文摘The study of temperature-driven phase transitions is significant in phosphate chemistry,as these transitions often lead to unique physical properties for specific applications,such as catalysis,energy storage,ion conduction,and nonlinear optics[1–3].The phase transition from room temperature(RT)to high temperature(HT)in phosphates is always from periodic structures to disordered or amorphous states[4–8].At RT,phosphates often maintain a highly ordered crystalline structure,which is stabilized by the lower thermal energy.As the temperature increases,the thermal energy disrupts the periodic arrangement of atoms and leads to a phase transition,where the once ordered structure becomes increasingly disordered or even amorphous.
基金supported by the National Natural Science Foundation of China(Grant Nos.52272119,51872177,52202143,52173263 and 22308283)the Young Talent Support Plan of Shaanxi Province and the Shaanxi Sanqin Scholars Innovation Team,National Key R&D Program of China(No.2022YFB3603703)the Qinchuangyuan High-level Talent Project of Shaanxi(No.QCYRCXM-2022-219)and the Youth Innovation Team of Shaanxi Universities and the Scientific research fund for high-level talents of Xijing University(No.XJ23B10).
文摘A series of tungsten bronze(Sr_(2-x)Bi_(x)Ag_(0.2)Na_(0.8))(Nb_(4.8-x)Zr_(x)Sb_(0.2))O15 compounds were fabricated by solidstate method to systematically study the impacts of co-doping Bi^(3+)/Zr^(4+)ions in A/B-sites on the structures,relaxor characteristics,and energy-storage performances.The relationship between structures and relaxor behaviors are summarized as three main points:(1)with increasing the amount of codoping Bi^(3+)/Zr^(4+)ions,the crystal structure evolved from an orthorhombic Bbm^(2) to a tetragonal paraelectric P4/mbm symmetry at room temperature;(2)enhancing relaxor characteristics at room temperature was achieved by tailoring the temperature region of T_(m)-T_(B)(T_(m) is the dielectric maximum temperature,T_(B) is the Burns temperature),which could be attributed to the incommensurate local structure modulations associated with the orthogonal distortion of P4bm symmetry and the appearance of microdomains;(3)The co-introduction of Bi^(3+)and Zr^(4+)could also played an important role in inhibiting the grain sizes,increasing resistivity and band-gap to enhance the breakdown strength.Finally,a superior recoverable energy-storage density(3.61 J/cm^(3))and an ultrahigh energy efficiency(90%)were obtained simultaneously at 389 kV/cm in BZ0.05 ceramics.Moreover,an outstanding power density(158.98 MW/cm^(3))together with a current density of 1422.29 A/cm^(2)was realized at 220 kV/cm from the charging-discharging performance measurements.The excellent energy-storage performance(ESPs)make the environmentally friendly BZ0.05 samples show enormous potential in high-power capacitor applications.
