Two-dimensional(2D)materials with tunable electronic transitions are vital for next-generation electronics and energy storage technologies.Here,we demonstrate a novel,thermally-driven,reversible modulation of electron...Two-dimensional(2D)materials with tunable electronic transitions are vital for next-generation electronics and energy storage technologies.Here,we demonstrate a novel,thermally-driven,reversible modulation of electronic conductivity in the quaternary heteroanionic 2D van der Waals superlattice Bi_(4)O_(4)SeCl_(2).Systematic thermal annealing of bulk Bi_(4)O_(4)SeCl_(2)induces a striking reversible transition from insulating to semiconducting behavior,accompanied by a 10~6 times magnitude enhancement in electrical conductivity.This dramatic transformation originates from thermally mediated defect annihilation and grain boundary elimination,substantially reducing carrier scattering barriers and enhancing intrinsic carrier concentration.Moreover,leveraging its intrinsic layered structure,we successfully exfoliated Bi_(4)O_(4)SeCl_(2)into nanosheets(~1.5 nm in thickness)and utilized these exfoliated layers as interfacial coatings on Zn electrodes,markedly improving dendrite suppression and extending the cycling stability of Zn-ion hybrid capacitors and Zn/MnO_(2)batteries.Our work elucidates crucial defect-driven micro s tructural mechanisms responsible for thermally-induced reversible electronic transitions,establishing heteroanionic Bi_(4)O_(4)SeCl_(2)as a promising platform for advanced electronic and energystorage materials engineering.展开更多
Polyacrylate-based conductive coatings were prepared from polyacrylate emulsion as matrix and carbon black (CB) whose surface was treated with titanate coupling agent as conducting particles.One kind of organic crysta...Polyacrylate-based conductive coatings were prepared from polyacrylate emulsion as matrix and carbon black (CB) whose surface was treated with titanate coupling agent as conducting particles.One kind of organic crystal was added to study its effects on the electrical conductivity and PTC(positive temperature coefficient)effect of the conductive coatings.Experimental results show that the coatings containing only polyacrylate emulsion and CB exhibit an excellent electrical conductivity but bad PTC effect,and when organic crystal is added,PTC effect is characterized and can increase by 2 orders of magtitude.The critical transformation temperature of polyacrylate emulsion/CB PTC composites is decided by melting point of organic crystals.展开更多
（Ca, Mn）-codoped Ba1-xSrxTiO3 （BST） solid solution, i.e. Ba0.4Sr0.5Ca0.08Mn0.02TiO3, was successfully synthesized via sol-gel process. The product was characterized by TG-DTA thermal analyses, XRD, TEM. The effect...（Ca, Mn）-codoped Ba1-xSrxTiO3 （BST） solid solution, i.e. Ba0.4Sr0.5Ca0.08Mn0.02TiO3, was successfully synthesized via sol-gel process. The product was characterized by TG-DTA thermal analyses, XRD, TEM. The effects of both curing temperature and applied voltage on the resistance, etc. were investigated. It showed that the structure of BST was unable to be changed even though it was codoped by Ca^2＋ and Mn^2＋. TEM photographs demonstrated the influence of curing temperature on the morphologies of the tested samples. The dependence of resistance on the curing temperature illustrated that （Ca, Mn）-codoped BST was capable of exhibiting the positive temperature coefficient （PTC） effect at low frequency; nevertheless, it might display the negative temperature coefficient （NTC） effect at other frequencies. The relationships between the resistance and applied voltage revealed that the resistance property of （Ca, Mn）-codoped BST appeared at low frequencies, but its property of capacitive reactance might present at high frequency. These findings mean that the electrical property of BST can be adjusted by codoping method. These phenomena can be explained by the grain boundary resistance effect, Heywang model and ion polarization theory.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFA1200903)National Natural Science Foundation of China(Nos.22175203,22006023,and 11974435)+1 种基金Natural Science Foundation of Guangdong Province(Nos.2022B1515020065 and 2020A1515110821,2023A1515010841,2025A1515010050)Guangzhou Science and Technology Project(No.202102020126)
文摘Two-dimensional(2D)materials with tunable electronic transitions are vital for next-generation electronics and energy storage technologies.Here,we demonstrate a novel,thermally-driven,reversible modulation of electronic conductivity in the quaternary heteroanionic 2D van der Waals superlattice Bi_(4)O_(4)SeCl_(2).Systematic thermal annealing of bulk Bi_(4)O_(4)SeCl_(2)induces a striking reversible transition from insulating to semiconducting behavior,accompanied by a 10~6 times magnitude enhancement in electrical conductivity.This dramatic transformation originates from thermally mediated defect annihilation and grain boundary elimination,substantially reducing carrier scattering barriers and enhancing intrinsic carrier concentration.Moreover,leveraging its intrinsic layered structure,we successfully exfoliated Bi_(4)O_(4)SeCl_(2)into nanosheets(~1.5 nm in thickness)and utilized these exfoliated layers as interfacial coatings on Zn electrodes,markedly improving dendrite suppression and extending the cycling stability of Zn-ion hybrid capacitors and Zn/MnO_(2)batteries.Our work elucidates crucial defect-driven micro s tructural mechanisms responsible for thermally-induced reversible electronic transitions,establishing heteroanionic Bi_(4)O_(4)SeCl_(2)as a promising platform for advanced electronic and energystorage materials engineering.
文摘Polyacrylate-based conductive coatings were prepared from polyacrylate emulsion as matrix and carbon black (CB) whose surface was treated with titanate coupling agent as conducting particles.One kind of organic crystal was added to study its effects on the electrical conductivity and PTC(positive temperature coefficient)effect of the conductive coatings.Experimental results show that the coatings containing only polyacrylate emulsion and CB exhibit an excellent electrical conductivity but bad PTC effect,and when organic crystal is added,PTC effect is characterized and can increase by 2 orders of magtitude.The critical transformation temperature of polyacrylate emulsion/CB PTC composites is decided by melting point of organic crystals.
文摘（Ca, Mn）-codoped Ba1-xSrxTiO3 （BST） solid solution, i.e. Ba0.4Sr0.5Ca0.08Mn0.02TiO3, was successfully synthesized via sol-gel process. The product was characterized by TG-DTA thermal analyses, XRD, TEM. The effects of both curing temperature and applied voltage on the resistance, etc. were investigated. It showed that the structure of BST was unable to be changed even though it was codoped by Ca^2＋ and Mn^2＋. TEM photographs demonstrated the influence of curing temperature on the morphologies of the tested samples. The dependence of resistance on the curing temperature illustrated that （Ca, Mn）-codoped BST was capable of exhibiting the positive temperature coefficient （PTC） effect at low frequency; nevertheless, it might display the negative temperature coefficient （NTC） effect at other frequencies. The relationships between the resistance and applied voltage revealed that the resistance property of （Ca, Mn）-codoped BST appeared at low frequencies, but its property of capacitive reactance might present at high frequency. These findings mean that the electrical property of BST can be adjusted by codoping method. These phenomena can be explained by the grain boundary resistance effect, Heywang model and ion polarization theory.
