The structures and elasticities of phase B silicates with different water and iron（Fe） content are obtained by firstprinciples simulation to understand the effects of water and Fe on their properties under high pres...The structures and elasticities of phase B silicates with different water and iron（Fe） content are obtained by firstprinciples simulation to understand the effects of water and Fe on their properties under high pressure.The lattice constants a and b decrease with increasing water content.On the contrary,c increases with increasing water content.On the other hand,the b and c decrease with increasing Fe content while a increases with increasing Fe content.The decrease of M（metal）–O octahedral volume is greater than the decrease of SiO polyhedral volume over the same pressure range.The density,bulk modulus and shear modulus of phase B increase with increasing Fe content and decrease with increasing water content.The compressional wave velocity（Vp） and shear wave velocity（Vs） of phase B decrease with increasing water and Fe content.The comparisons of density and wave velocity between phase B silicate and the Earth typical structure provide the evidence for understanding the formation of the X-discontinuity zone of the mantle.展开更多
The lead-free perovskites Cs_(3)B_(2)X_(9)(B=Sb,Bi;X=Cl,Br,I)as the popular photoelectric materials have excellent optical properties with lower toxicity.In this study,we systematically investigate the stable monolaye...The lead-free perovskites Cs_(3)B_(2)X_(9)(B=Sb,Bi;X=Cl,Br,I)as the popular photoelectric materials have excellent optical properties with lower toxicity.In this study,we systematically investigate the stable monolayer Cs_(3)B_(2)X_(9)and bilayer vertical heterostructure Cs_(3)B_(2)X_(9)/Cs3B02X9(B,B0=Sb,Bi;X=Cl,Br,I)via first-principles simulations.By exploring the electrical structures and band edge positions,we find the band gap reduction and the band type transition in the heterostructure Cs_(3)B_(2)X_(9)/Cs3B02X9 due to the charge transfer between layers.Furthermore,the results of optical properties reveal light absorption from the visible light to UV region,especially monolayer Cs3Sb2I9 and heterostructure Cs3Sb2I9/Cs3Bi2I9,which have absorption peaks in the visible light region,leading to the possibility of photocatalytic water splitting.These results provide insights for more two-dimensional semiconductors applied in the optoelectronic and photocatalytic fields.展开更多
Metallic hydrogen and hydride materials stand as promising avenues to achieve room-temperature superconductivity.Characterized by their high phonon frequencies and moderate coupling strengths,several high-pressure hyd...Metallic hydrogen and hydride materials stand as promising avenues to achieve room-temperature superconductivity.Characterized by their high phonon frequencies and moderate coupling strengths,several high-pressure hydrides were theoretically predicted to exhibit transition temperatures(Tc)exceeding 250 K,a claim further substantiated by experimental evidence.In an effort to push Tc beyond room temperature,we introduce a dynamical method that involves stimulating hydrides with mid-infrared lasers.Employing Floquet first-principles simulations,we observe that in a nonequilibrium state induced by light,both the electronic density of states and the coupling to highenergy phonons see notable enhancements.These simultaneous improvements collectively could potentially result in an estimated 20%–30%rise in Tc in practical pump conditions.Our theoretical investigation,therefore,offers a novel strategy to potentially raise the Tc of hydrides above room temperature.展开更多
基金Project supported by the Science Fund from the Key Laboratory of Earthquake Prediction,Institute of Earthquake Science,China Earthquake Administration(Grant No.2016IES010104)the National Natural Science Foundation of China(Grant Nos.41174071,41273073,41373060,and 41573121)
文摘The structures and elasticities of phase B silicates with different water and iron（Fe） content are obtained by firstprinciples simulation to understand the effects of water and Fe on their properties under high pressure.The lattice constants a and b decrease with increasing water content.On the contrary,c increases with increasing water content.On the other hand,the b and c decrease with increasing Fe content while a increases with increasing Fe content.The decrease of M（metal）–O octahedral volume is greater than the decrease of SiO polyhedral volume over the same pressure range.The density,bulk modulus and shear modulus of phase B increase with increasing Fe content and decrease with increasing water content.The compressional wave velocity（Vp） and shear wave velocity（Vs） of phase B decrease with increasing water and Fe content.The comparisons of density and wave velocity between phase B silicate and the Earth typical structure provide the evidence for understanding the formation of the X-discontinuity zone of the mantle.
基金supported by the National Key R&D Program of China(Grant No.2017YFA0303600)the National Natural Science Foundation of China(Grant No.11974253)the Science Specialty Program of Sichuan University(Grand No.2020SCUNL210)。
文摘The lead-free perovskites Cs_(3)B_(2)X_(9)(B=Sb,Bi;X=Cl,Br,I)as the popular photoelectric materials have excellent optical properties with lower toxicity.In this study,we systematically investigate the stable monolayer Cs_(3)B_(2)X_(9)and bilayer vertical heterostructure Cs_(3)B_(2)X_(9)/Cs3B02X9(B,B0=Sb,Bi;X=Cl,Br,I)via first-principles simulations.By exploring the electrical structures and band edge positions,we find the band gap reduction and the band type transition in the heterostructure Cs_(3)B_(2)X_(9)/Cs3B02X9 due to the charge transfer between layers.Furthermore,the results of optical properties reveal light absorption from the visible light to UV region,especially monolayer Cs3Sb2I9 and heterostructure Cs3Sb2I9/Cs3Bi2I9,which have absorption peaks in the visible light region,leading to the possibility of photocatalytic water splitting.These results provide insights for more two-dimensional semiconductors applied in the optoelectronic and photocatalytic fields.
基金supported by the Air Force Office of Scientific Research Young Investigator Program under grant FA9550-23-1-0153W.-C.C. and Y.W. also acknowledge support from the National Science Foundation (NSF) award DMR-2132338+1 种基金A.D.S. acknowledges support from the NSF awards No. OIA-2148653 and DMR-2142801Simulation results were obtained using the Frontera computing system at the Texas Advanced Computing Center. Frontera is made possible by NSF Award No. OAC-1818253.
文摘Metallic hydrogen and hydride materials stand as promising avenues to achieve room-temperature superconductivity.Characterized by their high phonon frequencies and moderate coupling strengths,several high-pressure hydrides were theoretically predicted to exhibit transition temperatures(Tc)exceeding 250 K,a claim further substantiated by experimental evidence.In an effort to push Tc beyond room temperature,we introduce a dynamical method that involves stimulating hydrides with mid-infrared lasers.Employing Floquet first-principles simulations,we observe that in a nonequilibrium state induced by light,both the electronic density of states and the coupling to highenergy phonons see notable enhancements.These simultaneous improvements collectively could potentially result in an estimated 20%–30%rise in Tc in practical pump conditions.Our theoretical investigation,therefore,offers a novel strategy to potentially raise the Tc of hydrides above room temperature.
