Low-dimensional materials have excellent properties which are closely related to their dimensionality.However,the growth mechanism underlying tunable dimensionality from 2D triangles to 1D ribbons of such materials is...Low-dimensional materials have excellent properties which are closely related to their dimensionality.However,the growth mechanism underlying tunable dimensionality from 2D triangles to 1D ribbons of such materials is still unrevealed.Here,we establish a general kinetic Monte Carlo model for transition metal dichalcogenides(TMDs) growth to address such an issue.Our model is able to reproduce several key findings in experiments,and reveals that the dimensionality is determined by the lattice mismatch and the interaction strength between TMDs and the substrate.We predict that the dimensionality can be well tuned by the interaction strength and the geometry of the substrate.Our work deepens the understanding of tunable dimensionality of low-dimensional materials and may inspire new concepts for the design of such materials with expected dimensionality.展开更多
As a simple binary compound, p-type SnS shows great competitiveness in thermoelectrics due to the certain appealing carrier and phonon transport behaviors, coupled with its cost-effectiveness, earth-abundance and envi...As a simple binary compound, p-type SnS shows great competitiveness in thermoelectrics due to the certain appealing carrier and phonon transport behaviors, coupled with its cost-effectiveness, earth-abundance and environmental compatibility. To promote the application of low-cost thermoelectric devices, we synthesized n-type SnS crystals through bromine doping. Herein, we report a high in-plane power factor of ~28 μW cm^(-1)K^(-2), and attribute it to an outstanding in-plane carrier mobility in the crystal form and the large Seebeck coefficient benefitting from the low carrier concentration. The calculations of elastic properties show that the low lattice thermal conductivity in SnS is closely related to its strong anharmonicity. Combining the excellent electrical transport properties with low thermal conductivity, a final ZT of ~0.4 is attained at 300 K, projecting a conversion efficiency of ~5% at 873 K along the in-plane direction.展开更多
First-principles calculations,which are based on the plane-wave pseudopotential approach to density functional perturbation theory within the local density approximation,have been performed to investigate the structur...First-principles calculations,which are based on the plane-wave pseudopotential approach to density functional perturbation theory within the local density approximation,have been performed to investigate the structural,lattice dynamical and thermodynamic properties of zinc blende(B3) structure magnesium chalcogenides:MgS,MgSe and MgTe.The results of ground state parameters and phonon dispersion are compared and agree well with the experimental data available and other calculations.We obtain the change of Born effective charge and LO-TO splitting under hydrostatic pressure.Finally,by the calculations of phonon frequencies,some thermodynamic properties such as the entropy,heat capacity,internal energy,and free energy are also successfully obtained.展开更多
基金supported by the Ministry of Science and Technology (No.2018YFA0208702)the National Natural Science Foundation of China (No.32090044,No. 21973085,No.21833007,No.21790350)+1 种基金Anhui Initiative in Quantum Information Technologies (AHY 090200)the Fundamental Research Funds for the Central Universities (WK2340000104)。
文摘Low-dimensional materials have excellent properties which are closely related to their dimensionality.However,the growth mechanism underlying tunable dimensionality from 2D triangles to 1D ribbons of such materials is still unrevealed.Here,we establish a general kinetic Monte Carlo model for transition metal dichalcogenides(TMDs) growth to address such an issue.Our model is able to reproduce several key findings in experiments,and reveals that the dimensionality is determined by the lattice mismatch and the interaction strength between TMDs and the substrate.We predict that the dimensionality can be well tuned by the interaction strength and the geometry of the substrate.Our work deepens the understanding of tunable dimensionality of low-dimensional materials and may inspire new concepts for the design of such materials with expected dimensionality.
基金supported by Beijing Natural Science Foundation (JQ18004)the National Key Research and Development Program of China (2018YFA0702100 and 2018YFB0703600)+4 种基金the National Natural Science Foundation of China (51772012)Shenzhen Peacock Plan team (KQTD2016022619565991)the National Postdoctoral Program for Innovative Talents (BX20200028)the 111 Project (B17002)support from the National Science Fund for Distinguished Young Scholars (51925101)。
文摘As a simple binary compound, p-type SnS shows great competitiveness in thermoelectrics due to the certain appealing carrier and phonon transport behaviors, coupled with its cost-effectiveness, earth-abundance and environmental compatibility. To promote the application of low-cost thermoelectric devices, we synthesized n-type SnS crystals through bromine doping. Herein, we report a high in-plane power factor of ~28 μW cm^(-1)K^(-2), and attribute it to an outstanding in-plane carrier mobility in the crystal form and the large Seebeck coefficient benefitting from the low carrier concentration. The calculations of elastic properties show that the low lattice thermal conductivity in SnS is closely related to its strong anharmonicity. Combining the excellent electrical transport properties with low thermal conductivity, a final ZT of ~0.4 is attained at 300 K, projecting a conversion efficiency of ~5% at 873 K along the in-plane direction.
基金Supported by Education Department Foundation of Liaoning Province of China under Grant Nos. 201064145,2010397Education Science Foundation of Liaoning of China under Grant No. 201102166
文摘First-principles calculations,which are based on the plane-wave pseudopotential approach to density functional perturbation theory within the local density approximation,have been performed to investigate the structural,lattice dynamical and thermodynamic properties of zinc blende(B3) structure magnesium chalcogenides:MgS,MgSe and MgTe.The results of ground state parameters and phonon dispersion are compared and agree well with the experimental data available and other calculations.We obtain the change of Born effective charge and LO-TO splitting under hydrostatic pressure.Finally,by the calculations of phonon frequencies,some thermodynamic properties such as the entropy,heat capacity,internal energy,and free energy are also successfully obtained.
