Layered rare-earth metal oxides,harnessing the dual properties of oxides and two-dimensional layered materials,exhibit remarkable thermal stability and quantum confinement effects.Therefore,this work adopts the first-...Layered rare-earth metal oxides,harnessing the dual properties of oxides and two-dimensional layered materials,exhibit remarkable thermal stability and quantum confinement effects.Therefore,this work adopts the first-principles calculation combined with the Boltzmann transport theory to predict the thermoelectric properties of NdZnSbO compound.The coexistence of weak interlayer van der Waals interactions,robust intralayer ionic bonding,and partial covalent bonding leads to remarkable bonding heterogeneity,which engenders pronounced phonon scattering and imposes constraints on thermal transport along the out-of-plane direction.The weakened chemical bonds induced by the antibonding states,together with the rattling-like behavior of the Zn atom,culminate in the profound anharmonicity in the layered NdZnSbO compound.The weakening bond and heavy element contribute to the softness of phonon modes,which significantly diminishes the phonon group velocity.The redistribution-dominated four-phonon scattering process spans a large optical gap,which effectively reduces the lattice thermal conductivity.The NdZnSbO compound exhibits direct semiconductor characteristic with a bandgap of 0.73 e V by adopting the Heyd-Scuseria-Ernzerhof(HSE06)functional in combination with spin–orbit coupling(SOC)effect.The multi-valley feature of NdZnSbO compound augur favorably for band degeneracy,thus amplifying the power factor.Consequently,an optimal figure-of-merit(ZT)of 3.40 at 900 K is achieved for the n-type NdZnSbO compound.The present study delves deeply insights into the origins for the low thermal conductivity of NdZnSbO compound and proposes an optimization scheme to enhance overall thermoelectric performance.展开更多
The salt-inclusion materials have drawn significant attention for their manifold structural chemistry and novel physical/chemical properties.Herein,two new salt-inclusion chalcohalides,[Cs_(6)Cl][Ga_(5)GeQ_(12)](Q=S,S...The salt-inclusion materials have drawn significant attention for their manifold structural chemistry and novel physical/chemical properties.Herein,two new salt-inclusion chalcohalides,[Cs_(6)Cl][Ga_(5)GeQ_(12)](Q=S,Se),have been discovered via hightemperature flux methods.The two isostructural compounds are constructed by porous[Ga_(5)GeQ_(12)]^(5−)layers with[ClCs_(6)]^(5+)octahedra filled in the holes.The[Ga_(5)GeQ_(12)]^(5−)layer is composed of the honeycomb-like(Ga/Ge)_(18)Q_(42)rings containing(Ga/Ge)_(3)Q_(9)trimer as basic unit.The band gaps of the two compounds are 3.90 and 2.89 eV,respectively.[Cs_(6)Cl][Ga_(5)GeS_(12)]exhibits interesting two-band emission properties which are related to the intermediate-band electronic structure revealed by density functional theory(DFT)calculations.Owing to the porous layered structure,[Cs_(6)Cl][Ga_(5)GeS_(12)]exhibits topological ion exchange ability towards Cd^(2+)ions with the maximum sorption capacity of 250 mg/g and high distribution coefficient(Kd)near 106 mL/g.This work further enriches the structural diversity of salt-inclusion materials and extends their potential application range to ion exchange adsorption.展开更多
基金Financial supports from the National Natural Science Foundation of China(21503039)Department of Science and Technology of Liaoning Province(2019MS164)+1 种基金Department of Education of Liaoning Province(LJ2020JCL034)Discipline Innovation Team of Liaoning Technical University(LNTU20TD-16)are greatly acknowledged。
文摘Layered rare-earth metal oxides,harnessing the dual properties of oxides and two-dimensional layered materials,exhibit remarkable thermal stability and quantum confinement effects.Therefore,this work adopts the first-principles calculation combined with the Boltzmann transport theory to predict the thermoelectric properties of NdZnSbO compound.The coexistence of weak interlayer van der Waals interactions,robust intralayer ionic bonding,and partial covalent bonding leads to remarkable bonding heterogeneity,which engenders pronounced phonon scattering and imposes constraints on thermal transport along the out-of-plane direction.The weakened chemical bonds induced by the antibonding states,together with the rattling-like behavior of the Zn atom,culminate in the profound anharmonicity in the layered NdZnSbO compound.The weakening bond and heavy element contribute to the softness of phonon modes,which significantly diminishes the phonon group velocity.The redistribution-dominated four-phonon scattering process spans a large optical gap,which effectively reduces the lattice thermal conductivity.The NdZnSbO compound exhibits direct semiconductor characteristic with a bandgap of 0.73 e V by adopting the Heyd-Scuseria-Ernzerhof(HSE06)functional in combination with spin–orbit coupling(SOC)effect.The multi-valley feature of NdZnSbO compound augur favorably for band degeneracy,thus amplifying the power factor.Consequently,an optimal figure-of-merit(ZT)of 3.40 at 900 K is achieved for the n-type NdZnSbO compound.The present study delves deeply insights into the origins for the low thermal conductivity of NdZnSbO compound and proposes an optimization scheme to enhance overall thermoelectric performance.
基金supported by the National Natural Science Foundation of China (22005006,21871008,22001263)the China Postdoctoral Science Foundation (2019M660298,2020T130009)
文摘The salt-inclusion materials have drawn significant attention for their manifold structural chemistry and novel physical/chemical properties.Herein,two new salt-inclusion chalcohalides,[Cs_(6)Cl][Ga_(5)GeQ_(12)](Q=S,Se),have been discovered via hightemperature flux methods.The two isostructural compounds are constructed by porous[Ga_(5)GeQ_(12)]^(5−)layers with[ClCs_(6)]^(5+)octahedra filled in the holes.The[Ga_(5)GeQ_(12)]^(5−)layer is composed of the honeycomb-like(Ga/Ge)_(18)Q_(42)rings containing(Ga/Ge)_(3)Q_(9)trimer as basic unit.The band gaps of the two compounds are 3.90 and 2.89 eV,respectively.[Cs_(6)Cl][Ga_(5)GeS_(12)]exhibits interesting two-band emission properties which are related to the intermediate-band electronic structure revealed by density functional theory(DFT)calculations.Owing to the porous layered structure,[Cs_(6)Cl][Ga_(5)GeS_(12)]exhibits topological ion exchange ability towards Cd^(2+)ions with the maximum sorption capacity of 250 mg/g and high distribution coefficient(Kd)near 106 mL/g.This work further enriches the structural diversity of salt-inclusion materials and extends their potential application range to ion exchange adsorption.
