In this work,the thermodynamic,mechanical properties and electronic behaviors of D022-TiAl3 doped with W and 15 groupⅣM(M=C,Ge,Pb,Si and Sn)dopants are investigated by DFT methods.We established that ductility can be...In this work,the thermodynamic,mechanical properties and electronic behaviors of D022-TiAl3 doped with W and 15 groupⅣM(M=C,Ge,Pb,Si and Sn)dopants are investigated by DFT methods.We established that ductility can be improved using multi-doping approach and revealed the mechanisms behind such brittle-to-ductile transition.In addition,it is found that there is linearity between changes in Young’s modulus and tensile/compre s sive strain ratio.An alternate insight into brittle-to-ductile transition during ductile mode cutting of brittle materials is proposed.展开更多
Structural distortions in nano-materials can induce dramatic changes in their electronic properties. This situation is well manifested in graphene, a two-dimensional honeycomb structure of carbon atoms with only one a...Structural distortions in nano-materials can induce dramatic changes in their electronic properties. This situation is well manifested in graphene, a two-dimensional honeycomb structure of carbon atoms with only one atomic layer thickness. In particular, strained graphene can result in both charging effects and pseudo-magnetic fields, so that controlled strain on a perfect graphene lattice can be tailored to yield desirable electronic properties. Here, we describe the theoretical foundation for strain-engineering of the electronic properties of graphene, and then provide experimental evidence for strain-induced pseudo-magnetic fields and charging effects in monolayer graphene. We further demonstrate the feasibility of nano-scale strain engineering for graphene-based devices by means of theoretical simulations and nano-fabrication technology.展开更多
The van der Waals interface structures and behaviors are of great impor-tance in determining the physical properties of two-dimensional atomic crystals and their heterostructures.The delicate interfacial properties ar...The van der Waals interface structures and behaviors are of great impor-tance in determining the physical properties of two-dimensional atomic crystals and their heterostructures.The delicate interfacial properties are sensitively dependent on the mechanical behaviors of atomically thin films under external strain.Here,we investigated the strain-engineered rippling structures at the CVD-grown bilayer-MoS_(2) interface with advanced atomic force microscopy(AFM).The in-plane compressive strain is sequentially introduced into the 1L-substrate and 2L-1L interface of bilayer-MoS_(2) flakes via a fast-cooling process.The thermal strain-engi-neered rippling structures were directly visualized at the central 2H-and 3R-MoS_(2) bilayer regions with friction force microscopy(FFM)and bimodal AFM techniques.These rippling structures can be further artifi-cially manipulated into the beating-like rippling features and fully erased via the contact mode AFM scanning.Our results shed lights on the strain-engineered interfacial structures of two-dimensional materials and also inspire the further investigation on the interface engineering of their elec-tronicandoptical properties.展开更多
Density functional and many-body perturbation theories calculations were carried out to investigate fundamental and optical bandgap, exciton binding energy and optical absorption property of normal and strain- and twi...Density functional and many-body perturbation theories calculations were carried out to investigate fundamental and optical bandgap, exciton binding energy and optical absorption property of normal and strain- and twist-engineered few-layer black phosphorus （BP）. We found that the fundamental bandgaps of few layer BP can be engineered by layer stacking and in-plane strain, with linear relationships to their associated exciton binding energies. The strain-dependent optical absorption behaviors are also anisotropic that the position of the first absorption peak monotonically blue-shifts as the strain applies to either direction for incident light polarized along the armchair direction, but this is not the case for that along the zigzag direction. Given those striking properties, we proposed two prototype devices for building potentially more balanced light absorbers and light filter passes, which promotes further applications and investigations of BP in nanoelectronics and optoelectronics.展开更多
基金partially supported by the National Research Foundation,Prime Minister’s Office,Singapore under its Marine Science Research and Development program(Award No.MSRDPP28)the Ministry of Education,Singapore under Tier 2 program(Award No.MOE2018-T2-1-163)。
文摘In this work,the thermodynamic,mechanical properties and electronic behaviors of D022-TiAl3 doped with W and 15 groupⅣM(M=C,Ge,Pb,Si and Sn)dopants are investigated by DFT methods.We established that ductility can be improved using multi-doping approach and revealed the mechanisms behind such brittle-to-ductile transition.In addition,it is found that there is linearity between changes in Young’s modulus and tensile/compre s sive strain ratio.An alternate insight into brittle-to-ductile transition during ductile mode cutting of brittle materials is proposed.
基金supported by the National Science Foundation under the Institute for Quantum Information and Matter at California Institute of Technology
文摘Structural distortions in nano-materials can induce dramatic changes in their electronic properties. This situation is well manifested in graphene, a two-dimensional honeycomb structure of carbon atoms with only one atomic layer thickness. In particular, strained graphene can result in both charging effects and pseudo-magnetic fields, so that controlled strain on a perfect graphene lattice can be tailored to yield desirable electronic properties. Here, we describe the theoretical foundation for strain-engineering of the electronic properties of graphene, and then provide experimental evidence for strain-induced pseudo-magnetic fields and charging effects in monolayer graphene. We further demonstrate the feasibility of nano-scale strain engineering for graphene-based devices by means of theoretical simulations and nano-fabrication technology.
基金supported by the National Key R&D Program of China(MOST)(Grant Nos.2023YFA1406500 and 2018YFE0202700)the National Natural Science Foundation of China(NSFC)(Nos.21622304,61674045,11604063,11974422,and 12104504)+2 种基金the Strategic Priority Research Program(Chinese Academy of Sciences,CAS)(No.XDB30000000)the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China[Nos.21XNLG27(Z.C.)and 22XNH095(H.D.)]supported by the Outstanding Innovative Talents Cultivation Funded Programs 2023 of Renmin University of China.
文摘The van der Waals interface structures and behaviors are of great impor-tance in determining the physical properties of two-dimensional atomic crystals and their heterostructures.The delicate interfacial properties are sensitively dependent on the mechanical behaviors of atomically thin films under external strain.Here,we investigated the strain-engineered rippling structures at the CVD-grown bilayer-MoS_(2) interface with advanced atomic force microscopy(AFM).The in-plane compressive strain is sequentially introduced into the 1L-substrate and 2L-1L interface of bilayer-MoS_(2) flakes via a fast-cooling process.The thermal strain-engi-neered rippling structures were directly visualized at the central 2H-and 3R-MoS_(2) bilayer regions with friction force microscopy(FFM)and bimodal AFM techniques.These rippling structures can be further artifi-cially manipulated into the beating-like rippling features and fully erased via the contact mode AFM scanning.Our results shed lights on the strain-engineered interfacial structures of two-dimensional materials and also inspire the further investigation on the interface engineering of their elec-tronicandoptical properties.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11274380, 11004244 and 91433103)the National Basic Research Program of China (Grant No. 2012CB932704)
文摘Density functional and many-body perturbation theories calculations were carried out to investigate fundamental and optical bandgap, exciton binding energy and optical absorption property of normal and strain- and twist-engineered few-layer black phosphorus （BP）. We found that the fundamental bandgaps of few layer BP can be engineered by layer stacking and in-plane strain, with linear relationships to their associated exciton binding energies. The strain-dependent optical absorption behaviors are also anisotropic that the position of the first absorption peak monotonically blue-shifts as the strain applies to either direction for incident light polarized along the armchair direction, but this is not the case for that along the zigzag direction. Given those striking properties, we proposed two prototype devices for building potentially more balanced light absorbers and light filter passes, which promotes further applications and investigations of BP in nanoelectronics and optoelectronics.
