The introduction of magnetism in SnTe-class topological crystalline insulators is a challenging subject with great importance in the quantum device applications. Based on the first-principles calculations, we have stu...The introduction of magnetism in SnTe-class topological crystalline insulators is a challenging subject with great importance in the quantum device applications. Based on the first-principles calculations, we have studied the defect energetics and magnetic properties of 3d transition-metal(TM)-doped SnTe. We find that the doped TM atoms prefer to stay in the neutral states and have comparatively high formation energies, suggesting that the uniform TMdoping in SnTe with a higher concentration will be difficult unless clustering. In the dilute doping regime, all the magnetic TMatoms are in the high-spin states, indicating that the spin splitting energy of 3d TM is stronger than the crystal splitting energy of the SnTe ligand. Importantly, Mn-doped SnTe has relatively low defect formation energy, largest local magnetic moment, and no defect levels in the bulk gap, suggesting that Mn is a promising magnetic dopant to realize the magnetic order for the theoretically-proposed large-Chern-number quantum anomalous Hall effect(QAHE) in SnTe.展开更多
Layered carbon materials(LCMs)are composed of basic carbon layer units,such as graphite,soft carbon,hard carbon,and graphene.While they have been widely applied in the anode of potassium-ion batteries,the potassium st...Layered carbon materials(LCMs)are composed of basic carbon layer units,such as graphite,soft carbon,hard carbon,and graphene.While they have been widely applied in the anode of potassium-ion batteries,the potassium storage mechanisms and performances of various LCMs are isolated and difficult to relate to each other.More importantly,there is a lack of a systematic understanding of the correlation between the basic microstructural unit(crystallinity and defects)and the potas-sium storage behavior.In this review,we explored the key structural factors affecting the potassium storage in LCMs,namely,the crystallinity and defects of carbon layers,and the key parameters(L_(a),L_(c),d_(002),I_(D)/I_(G))that characterize the crystallinity and defects of different carbon materials were extracted from various databases and literature sources.A structure–property database of LCMs was thus built,and the effects of these key structural parameters on the potassium storage properties,including the capacity,the rate and the working voltage plateau,were systematically analyzed.Based on the structure–prop-erty database analysis and the guidance of thermodynamics and kinetics,a relationship between various LCMs and potas-sium storage properties was established.Finally,with the help of machine learning,the key structural parameters of layered carbon anodes were used for the first time to predict the potassium storage performance so that the large amount of research data in the database could more effectively guide the scientific research and engineering application of LCMs in the future.展开更多
The coarsening-grained single-phase face-centered cubic(fcc)medium-entropy alloys(MEAs)normally exhibit insufficient strength for some engineering applications.Here,superior mechanical properties with ultimate tensile...The coarsening-grained single-phase face-centered cubic(fcc)medium-entropy alloys(MEAs)normally exhibit insufficient strength for some engineering applications.Here,superior mechanical properties with ultimate tensile strength of 1.6 GPa and fracture strain of 13.1%at ambient temperature have been achieved in a(CoCrNi)_(94)Ti_(3)Al_(3)MEA by carefully architecting the multi-scale heterogeneous structures.Electron microscopy characterization indicates that the superior mechanical properties mainly originated from the favorable heterogeneous fcc matrix(1-40μm)and the coherent sphericalγ’precipitates(10-100 nm),together with a high number density of crystalline defects(2-10 nm),including dislocations,small stacking faults,Lomer-Cottrell locks,and ultrafine deformation twins.展开更多
A number of zinc oxide(Zn O) films are deposited on silicon substrates using the magnetron sputtering method.After undergoing thermal treatment under different conditions, those films exhibit hexagonal wurtzite stru...A number of zinc oxide(Zn O) films are deposited on silicon substrates using the magnetron sputtering method.After undergoing thermal treatment under different conditions, those films exhibit hexagonal wurtzite structures and different photoluminescent characteristics. Besides the notable ultraviolet emission, which is related to the free exciton effect, a distinct blue fluorescence around 475 nm is found in some special samples.The blue photoluminescence emission of the Zn O film is believed to be caused by oxygen vacancies.展开更多
基金supported by the National Key Research and Development Program,the National Natural Science Foundation of China(Grant Nos.11334006 and 11504015)the Open Research Fund Program of the State Key Laboratory of Low-dimensional Quantum Physics(Grant No.KF201508)
文摘The introduction of magnetism in SnTe-class topological crystalline insulators is a challenging subject with great importance in the quantum device applications. Based on the first-principles calculations, we have studied the defect energetics and magnetic properties of 3d transition-metal(TM)-doped SnTe. We find that the doped TM atoms prefer to stay in the neutral states and have comparatively high formation energies, suggesting that the uniform TMdoping in SnTe with a higher concentration will be difficult unless clustering. In the dilute doping regime, all the magnetic TMatoms are in the high-spin states, indicating that the spin splitting energy of 3d TM is stronger than the crystal splitting energy of the SnTe ligand. Importantly, Mn-doped SnTe has relatively low defect formation energy, largest local magnetic moment, and no defect levels in the bulk gap, suggesting that Mn is a promising magnetic dopant to realize the magnetic order for the theoretically-proposed large-Chern-number quantum anomalous Hall effect(QAHE) in SnTe.
文摘Layered carbon materials(LCMs)are composed of basic carbon layer units,such as graphite,soft carbon,hard carbon,and graphene.While they have been widely applied in the anode of potassium-ion batteries,the potassium storage mechanisms and performances of various LCMs are isolated and difficult to relate to each other.More importantly,there is a lack of a systematic understanding of the correlation between the basic microstructural unit(crystallinity and defects)and the potas-sium storage behavior.In this review,we explored the key structural factors affecting the potassium storage in LCMs,namely,the crystallinity and defects of carbon layers,and the key parameters(L_(a),L_(c),d_(002),I_(D)/I_(G))that characterize the crystallinity and defects of different carbon materials were extracted from various databases and literature sources.A structure–property database of LCMs was thus built,and the effects of these key structural parameters on the potassium storage properties,including the capacity,the rate and the working voltage plateau,were systematically analyzed.Based on the structure–prop-erty database analysis and the guidance of thermodynamics and kinetics,a relationship between various LCMs and potas-sium storage properties was established.Finally,with the help of machine learning,the key structural parameters of layered carbon anodes were used for the first time to predict the potassium storage performance so that the large amount of research data in the database could more effectively guide the scientific research and engineering application of LCMs in the future.
基金This work was financially supported by the National Key Research and Development Program of China(No.2020YFB0311300ZL)the National Natural Science Foundation of China(No.52071343).
文摘The coarsening-grained single-phase face-centered cubic(fcc)medium-entropy alloys(MEAs)normally exhibit insufficient strength for some engineering applications.Here,superior mechanical properties with ultimate tensile strength of 1.6 GPa and fracture strain of 13.1%at ambient temperature have been achieved in a(CoCrNi)_(94)Ti_(3)Al_(3)MEA by carefully architecting the multi-scale heterogeneous structures.Electron microscopy characterization indicates that the superior mechanical properties mainly originated from the favorable heterogeneous fcc matrix(1-40μm)and the coherent sphericalγ’precipitates(10-100 nm),together with a high number density of crystalline defects(2-10 nm),including dislocations,small stacking faults,Lomer-Cottrell locks,and ultrafine deformation twins.
基金supported by the Natural Science Foundation of Shanghai (No. 13ZR1402600)the National Natural Science Foundation of China (No. 60578047)+3 种基金the National "973" Program of China (Nos. 2012CB934303 and 2009CB929201)the Shanghai Commission of Science and Technology (No. 06DJ14007)the National "02" Project of China (No. 2011ZX02402)the Natural Science Foundation of Shandong Province (No. 2011ZRFL019)
文摘A number of zinc oxide(Zn O) films are deposited on silicon substrates using the magnetron sputtering method.After undergoing thermal treatment under different conditions, those films exhibit hexagonal wurtzite structures and different photoluminescent characteristics. Besides the notable ultraviolet emission, which is related to the free exciton effect, a distinct blue fluorescence around 475 nm is found in some special samples.The blue photoluminescence emission of the Zn O film is believed to be caused by oxygen vacancies.