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
Designing novel van der Waals layered materials with low thermal conductivity and large power factor is important for the development of layered thermoelectric materials.Therefore,the novel van der Waals intercalated ...Designing novel van der Waals layered materials with low thermal conductivity and large power factor is important for the development of layered thermoelectric materials.Therefore,the novel van der Waals intercalated compound La_(2)Bi_(4)Cu_(2)O_(6)Se_(4),which is constructed by alternately stacking LaCuSeO and Bi_(2)O_(2)Se units along the c-axis in a 1:2 ratio,has designed for thermoelectric materials.The unique intercalated strategy leads to the four-band convergence at the valence band maximum,and the combination of multiple heavy band and light band,which significantly enhances the p-type doping power factor.The lattice thermal conductivities in La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)and LaCuSeO compounds are accurately calculated by considering the coherence contributions of the anharmonic phonon reformulations and the off-diagonal term of the heat flux operator.The weak bond property of the Cu d-Se p bonding causes phonon softening,reducing the lattice thermal conductivity.The intercalated Bi atom has stereochemically active lone-pair electrons,which causes acoustic-optical coupling and produces strong fourth acoustic-optical phonon scattering,suppressing low-frequency phonon transport.The carrier relaxation time is rationalized by considering multiple carrier scattering mechanisms.The p-type doping La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)achieves an average ZT of 2.3 at 700 K,and an optimal ZT of 2.7 along the in-plane direction.Our current work not only reveals the origin of the strong phonon scattering and large power factor of La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)compound,but also provides theoretical guidance for the design of La-based layered oxides for thermoelectric applications.展开更多
目的探讨慢性肾脏病患者中,尿酸排泄分数与肾功能的关系。方法搜集检测24 h尿相关指标的慢性肾脏病患者245例,根据尿酸排泄分数(fraction excretion of uric acid, FEUA)的四分位数间距分为4组(FEUA 1~4),分析尿酸排泄分数与肾功能的关...目的探讨慢性肾脏病患者中,尿酸排泄分数与肾功能的关系。方法搜集检测24 h尿相关指标的慢性肾脏病患者245例,根据尿酸排泄分数(fraction excretion of uric acid, FEUA)的四分位数间距分为4组(FEUA 1~4),分析尿酸排泄分数与肾功能的关系。运用相关性分析,研究FEUA与预估肾小球滤过率(eGFR)、24 h尿蛋白的关系。采用Logistic回归方法分析各临床指标与肾功能的关系。结果随着FEUA的逐渐升高,eGFR逐渐降低;而且FEUA与eGFR负相关( r =-0.591 , P <0.000 1);FEUA与24 h尿蛋白正相关( r =0.408, P <0.000 1)。Logistic回归表明,FEUA与肾功能相关(OR=1.085,95%CI=1.008~1.167, P =0.035)。结论在慢性肾脏病患者,FEUA是肾功能的危险因素;而且FEUA水平越高,肾功能越差。展开更多
Inspired by the excellent stability exhibited by experimentally synthesized two-dimensional(2D)MoSi_(2)N_(4) layered material,the thermal and electronic transport,and thermoelectric(TE)properties of MgAl2Te4 monolayer...Inspired by the excellent stability exhibited by experimentally synthesized two-dimensional(2D)MoSi_(2)N_(4) layered material,the thermal and electronic transport,and thermoelectric(TE)properties of MgAl2Te4 monolayer are systematically investigated using the First-principles calculations and Boltzmann transport theory.The mechanical stability,dynamic stability,and thermal stability(900 K)of the MgAl_(2)Te_(4) monolayer are demonstrated,respectively.The MgAl_(2)Te_(4) monolayer exhibits a bandgap of 1.35 eV using the HSE06 functional in combination with spin-orbit coupling(SOC)effect.Band convergence in the valence band is favorable to improve the thermoelectric properties.The rattling thermal damping effect caused by the weak bonding of Mgsingle bondTe bonds in MgAl2Te4 monolayer leads to ultra-low lattice thermal conductivity(0.95/0.38 W/(m·K)@300 K along the x-/y-direction),which is further demonstrated by the phonon group velocities,phonon relaxation time,Grüneisen parameters,and scattering mechanisms.The optimal zT of 3.28 at 900 K is achieved for the p-type MgAl_(2)Te_(4) monolayer,showing the great promising prospect for the excellent p-type thermoelectric material.Our current work not only reveals the underlying mechanisms responsible for the excellent TE properties,but also elaborates on the promising thermoelectric application of MgAl_(2)Te_(4) monolayer material at high temperature.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Financial supports from the National Natural Science Foundation of China(Grant No.21503039)Department of Science and Technology of Liaoning Province(Grant No.2019MS164)+1 种基金Department of Education of Liaoning Province(Grant No.LJ2020JCL034)Discipline Innovation Team of Liaoning Technical University(Grant No.LNTU20TD-16)are greatly acknowledged。
文摘Designing novel van der Waals layered materials with low thermal conductivity and large power factor is important for the development of layered thermoelectric materials.Therefore,the novel van der Waals intercalated compound La_(2)Bi_(4)Cu_(2)O_(6)Se_(4),which is constructed by alternately stacking LaCuSeO and Bi_(2)O_(2)Se units along the c-axis in a 1:2 ratio,has designed for thermoelectric materials.The unique intercalated strategy leads to the four-band convergence at the valence band maximum,and the combination of multiple heavy band and light band,which significantly enhances the p-type doping power factor.The lattice thermal conductivities in La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)and LaCuSeO compounds are accurately calculated by considering the coherence contributions of the anharmonic phonon reformulations and the off-diagonal term of the heat flux operator.The weak bond property of the Cu d-Se p bonding causes phonon softening,reducing the lattice thermal conductivity.The intercalated Bi atom has stereochemically active lone-pair electrons,which causes acoustic-optical coupling and produces strong fourth acoustic-optical phonon scattering,suppressing low-frequency phonon transport.The carrier relaxation time is rationalized by considering multiple carrier scattering mechanisms.The p-type doping La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)achieves an average ZT of 2.3 at 700 K,and an optimal ZT of 2.7 along the in-plane direction.Our current work not only reveals the origin of the strong phonon scattering and large power factor of La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)compound,but also provides theoretical guidance for the design of La-based layered oxides for thermoelectric applications.
文摘目的探讨慢性肾脏病患者中,尿酸排泄分数与肾功能的关系。方法搜集检测24 h尿相关指标的慢性肾脏病患者245例,根据尿酸排泄分数(fraction excretion of uric acid, FEUA)的四分位数间距分为4组(FEUA 1~4),分析尿酸排泄分数与肾功能的关系。运用相关性分析,研究FEUA与预估肾小球滤过率(eGFR)、24 h尿蛋白的关系。采用Logistic回归方法分析各临床指标与肾功能的关系。结果随着FEUA的逐渐升高,eGFR逐渐降低;而且FEUA与eGFR负相关( r =-0.591 , P <0.000 1);FEUA与24 h尿蛋白正相关( r =0.408, P <0.000 1)。Logistic回归表明,FEUA与肾功能相关(OR=1.085,95%CI=1.008~1.167, P =0.035)。结论在慢性肾脏病患者,FEUA是肾功能的危险因素;而且FEUA水平越高,肾功能越差。
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Inspired by the excellent stability exhibited by experimentally synthesized two-dimensional(2D)MoSi_(2)N_(4) layered material,the thermal and electronic transport,and thermoelectric(TE)properties of MgAl2Te4 monolayer are systematically investigated using the First-principles calculations and Boltzmann transport theory.The mechanical stability,dynamic stability,and thermal stability(900 K)of the MgAl_(2)Te_(4) monolayer are demonstrated,respectively.The MgAl_(2)Te_(4) monolayer exhibits a bandgap of 1.35 eV using the HSE06 functional in combination with spin-orbit coupling(SOC)effect.Band convergence in the valence band is favorable to improve the thermoelectric properties.The rattling thermal damping effect caused by the weak bonding of Mgsingle bondTe bonds in MgAl2Te4 monolayer leads to ultra-low lattice thermal conductivity(0.95/0.38 W/(m·K)@300 K along the x-/y-direction),which is further demonstrated by the phonon group velocities,phonon relaxation time,Grüneisen parameters,and scattering mechanisms.The optimal zT of 3.28 at 900 K is achieved for the p-type MgAl_(2)Te_(4) monolayer,showing the great promising prospect for the excellent p-type thermoelectric material.Our current work not only reveals the underlying mechanisms responsible for the excellent TE properties,but also elaborates on the promising thermoelectric application of MgAl_(2)Te_(4) monolayer material at high temperature.
