Developing highly active,cost-effective,and environmental friendly oxygen evolution reaction(OER)electrocatalysts facilitates various(photo)electrochemical processes.In this work,Fe3N nanoparticles encapsulated into N...Developing highly active,cost-effective,and environmental friendly oxygen evolution reaction(OER)electrocatalysts facilitates various(photo)electrochemical processes.In this work,Fe3N nanoparticles encapsulated into N-doped graphene nanoshells(Fe_(3)N@NG)as OER electrocatalysts in alkaline media were reported.Both the experimental and theoretical comparison between Fe_(3) N@NG and Fe_(3)N/NG,specifically including in situ Mossbauer analyses,demonstrated that the NG nanoshells improved interfacial electron transfer process from Fe_(3)N to NG to form high-valence Fe^(4+)ions(Fe^(4+)@NG),thus modifying electronic properties of the outer NG shells and subsequently electron transfer from oxygen intermediate to NG nanoshells for OER catalytic process.Meanwhile,the NG nanoshells also protected Fe-based cores from forming OER inactive and insulated Fe_(2)O_(3),leading to high OER stability.As a result,the as-formed Fe^(4+)@NG shows one of the highest electrocatalytic efficiency among reported Fe-based OER electrocatalysts,which can as well highly improve the photoelectrochemical water oxidation when used as the cocatalysts for the Fe_(2)O_(3) nanoarray photoanode.展开更多
Drug-associated reward memories are conducive to intense craving and often trigger relapse.Simvastatin has been shown to regulate lipids that are involved in memory formation but its influence on other cognitive proce...Drug-associated reward memories are conducive to intense craving and often trigger relapse.Simvastatin has been shown to regulate lipids that are involved in memory formation but its influence on other cognitive processes is elusive.Here,we used a mass spectrometry-based lipidomic method to evaluate the impact of simvastatin on the mouse brain in a cocaine-induced reinstatement paradigm.We found that simvastatin blocked the reinstatement of cocaine-induced conditioned place preference(CPP)without affecting CPP acquisition.Specifically,only simvastatin administered during extinction prevented cocaine-primed reinstatement.Global lipidome analysis showed that the nucleus accumbens was the region with the greatest degree of change caused by simvastatin.The metabolism of fatty-acids,phospholipids,and triacylglycerol was profoundly affected.Simvastatin reversed most of the effects on phospholipids induced by cocaine.The correlation matrix showed that cocaine and simvastatin significantly reshaped the lipid metabolic pathways in specific brain regions.Furthermore,simvastatin almost reversed all changes in the fatty acyl profile and unsaturation caused by cocaine.In summary,pre-extinction treatment with simvastatin facilitates cocaine extinction and prevents cocaine relapse with brain lipidome remodeling.展开更多
Based on the measurement of major and trace elements in suspended sediments in the low reaches of the Changjiang River during throughout a whole hydrologic year, the origins, seasonal variations, and fluxes of multiel...Based on the measurement of major and trace elements in suspended sediments in the low reaches of the Changjiang River during throughout a whole hydrologic year, the origins, seasonal variations, and fluxes of multielements and the human impacts on multielements transport processes have been analyzed along with the influence of weathering in the Changjiang River basin. The results show that most element contents were high in both autumn and winter and low in summer, which was largely caused by the dilution of discharge. Weathering detritus in the Changjiang River basin is the main source of most elements in suspended sediments. However, riverine pollution could bring more loadings of Cd, Pb, As and Zn into river water than it did a few decades ago. The annual average fluxes of Cd, Pb and Zn, which are major contamination elements, to the sea were 179 ± 21 tons/year, 7810 ± 675 tons/year, and 12,000 ± 1320 tons/year,respectively, in which approximately 8.7%, 11.9% and 2.7% of their loadings, respectively,were contributed by pollution inputs. Element exports mainly occurred in the summer(44.4%–57.4%) in the lower part of the Changjiang River. A general relationship between sediment retention and element content suggests a positive feedback mechanism for the decreased number of particles, in which element riverine loadings are reduced due to the enhanced trapping effect by the Three Gorges Dam(TGD). Compared to those in 1980,current element shares of the Changjiang River compared to the global budget have declined due to the construction of the TGD.展开更多
This study investigated the effects of hydroxyproline(Hyp)and vitamin C(VC)addition to practical diet on growth and flesh quality of Pacific white shrimp(Litopenaeus vannamei)cultured in low salinity water.The control...This study investigated the effects of hydroxyproline(Hyp)and vitamin C(VC)addition to practical diet on growth and flesh quality of Pacific white shrimp(Litopenaeus vannamei)cultured in low salinity water.The control diet was formulated to contain 200 g/kg fish meal(FM20),and then 14 g/kg coated hydroxyproline(50%)(FM20H),2 g/kg L-ascorbyl-2-phosphate(38%)(FM20C)and their combination(FM20HC)were added to the control diet to form four isoproteic(41.6%)and isolipidic(6.7%)diets.Pacific white shrimp with initial body weight of(1.50±0.05)g were fed the above four diets in low salinity water(salinity 1‰)for 8 weeks.The results showed that the combined supplementation of Hyp and VC(FM20HC)increased the weight gain by 13.4%,and decreased the feed conversion ratio by 0.18(P<0.05),while the individual supplementation(FM20H and FM20C groups)just numerically promoted the growth(P>0.05).In addition,the FM20HC group also showed higher protein and lipid retention than the FM20 group(P<0.05).In flesh quality,the supple-mentation of Hyp(FM20H)increased total collagen and heat-soluble collagen contents,flesh chewiness and free flavor amino acids contents(P<0.05).The supplementation of vC(FM20C)increased the contents of total collagen,heat-insoluble collagen and free flavor amino acids,and decreased flesh lactic acid,malondialdehyde contents and steaming loss(P<0.05).The combined supplementation of Hyp and VC(FM20HC)showed higher total collagen and heat-insoluble collagen contents than the individual supplementation(FM20H and FM20C)(P<0.05),and the myofiber density,flesh hardness and shear force in the FM20HC group were also significantly higher than those in the control(P<0.05).In summary,the combined supplementation of hydroxyproline and vc in practical diet with fishmeal content of 200 g/kg significantly improved the growth performance and flesh quality of L.vannamei cultured in low salinity water.展开更多
Layered two-dimensional(2D)materials have garnered marvelous attention in diverse fields,including sensors,capacitors,nanocomposites and transistors,owing to their distinctive structural morphologies and superior phys...Layered two-dimensional(2D)materials have garnered marvelous attention in diverse fields,including sensors,capacitors,nanocomposites and transistors,owing to their distinctive structural morphologies and superior physicochemical properties.Recently,layered quasi-2D materials,especially layered bismuth oxyselenide(Bi2O2Se),are of particular interest,because of their different interlayer interactions from other layered 2D materials.On this basis,this material offers richer and more intriguing physics,including high electron mobility,sizeable bandgap,and remarkable thermal and chemical durability,rendering it an utterly prospective contender for use in advanced electronic and optoelectronic applications.Herein,this article reviews the recent advances related with Bi2O2Se.Initially,its structural characterization,band structure,and basic properties are briefly introduced.Further,the synthetic strategies for the preparation of Bi_(2)O_(2)Se are presented.Furthermore,the diverse applications of Bi2O2Se in the field of electronics and optoelectronics,photocatalytic,solar cells and sensing were summarized in detail.Ultimately,the challenges and future perspectives of Bi2O2Se are included.展开更多
To address the critical challenge of balancing ultralow dielectric constant(k)with low coefficient of thermal expansion(CTE)in high-frequency electronic applications,this study develops a series of tri-armed benzocycl...To address the critical challenge of balancing ultralow dielectric constant(k)with low coefficient of thermal expansion(CTE)in high-frequency electronic applications,this study develops a series of tri-armed benzocyclobutene(BCB)-based resins via rational molecular design.Five functional monomers(Ph-BCB,Ph-ene-BCB,Ph-yne-BCB,TPA-yne-BCB,TPB-yne-BCB)were synthesized through Suzuki,Heck,and Sonogashira coupling reactions,followed by thermal curing to form crosslinked polymers.The introduction of branched architectures and rigid conjugated cores effectively enhanced free volume fraction while suppressing molecular chain mobility,achieving synergistic optimization of dielectric and thermomechanical properties.The cured resins exhibited exceptional performance:dielectric constants as low as 1.83(TPA-yne-BCB)at 1 kHz,dielectric loss below 0.0015,and CTE values ranging from 19.23–34.63 ppm℃^(−1),closely matching copper(16 ppm℃^(-1)).The SAXS and WAXS analyses confirmed that enlarged free volume and reduced polarization from optimized topology were key to low-k performance.Additionally,the materials demonstrated outstanding thermal stability(5%weight loss>500℃),high mechanical strength(elastic modulus up to 10 GPa),and hydrophobicity(water absorption<2%).This work provides a groundbreaking strategy for designing high-performance dielectric materials for 5G millimeterwave packaging,flexible electronics,and 3D heterogeneous integration.展开更多
Band degeneracy is effective in optimizing the power factors of thermoelectric(TE)materials by enhancing the Seebeck coefficients.In this study,we demonstrate this effect in model systems of layered oxyselenide family...Band degeneracy is effective in optimizing the power factors of thermoelectric(TE)materials by enhancing the Seebeck coefficients.In this study,we demonstrate this effect in model systems of layered oxyselenide family by the density functional theory(DFT)combined with semi-classical Boltzmann transport theory.TE transport performance of layered LaCuOSe and BiCuOSe are fully compared.The results show that due to the larger electrical conductivities caused by longer electron relaxation times,the n-type systems show better TE performance than p-type systems for both LaCuOSe and BiCuOSe.Besides,the conduction band degeneracy of LaCuOSe leads to a larger Seebeck coefficient and a higher optimal carrier concentration than n-type BiCuOSe,and thus a higher power factor.The optimal figure of merit(ZT)value of 1.46 for n-type LaCuOSe is 22%larger than that of 1.2 for n-type BiCuOSe.This study highlights the potential of wide band gap material LaCuOSe for highly efficient TE applications,and demonstrates that inducing band degeneracy by cations substitution is an effective way to enhance the TE performance of layered oxyselenides.展开更多
The high curing temperatures required for traditional benzocyclobutene(BCB)materials have posed limitations on their applicability in high-temperature-sensitivefields.To address this challenge,our work focuses on the ...The high curing temperatures required for traditional benzocyclobutene(BCB)materials have posed limitations on their applicability in high-temperature-sensitivefields.To address this challenge,our work focuses on the synthesis of a novel tetraphenylethylene(TPE)-functionalized BCB monomer,TPE–BCB,achieved through the introduction of an ether bond onto the BCB’s four-membered ring via Williamson reaction.TPE–BCB demonstrates remarkable low-temperature curing properties,characterized by a ring-opening peak temperature of 190◦C,representing a reduction of 60◦C compared to conventional BCBs.Fully cured TPE–BCB resins exhibit exceptional dielectric and mechanical properties,coupled with minimal water absorption.Additionally,the incorporation of TPE with aggregation-induced emission characteristics enhances the resins’luminescence and photolithographic capabilities.Notably,our TPE–BCB resins achieve impressive photolithography performance with a resolution ratio of up to 10μm.In contrast to conventional BCB-functionalized resins,TPE–BCB offers the dual advantage of low-temperature curing and luminescence.This development marks a significant step in the advance-ment of low-temperature curing BCB materials and serves as a pioneering example in the realm of multilayer wafer bonding materials.展开更多
To the Editor:Bronchial asthma is a respiratory disease with pathological features that mainly comprise changes in airway inflammation,airway remodeling,and airway hyperresponsiveness.
Over the past century,ferroelectricity has offered exciting opportunities for fundamental research and device applications.However,most of the discovered excellent ferroelectrics are oxide materials with large band ga...Over the past century,ferroelectricity has offered exciting opportunities for fundamental research and device applications.However,most of the discovered excellent ferroelectrics are oxide materials with large band gaps,limiting their potential for optoelectronics applications.Here using first-principles calculations we identify a new narrow-gap ferroelectric beyond oxides,i.e.,ferroelectric perovskite sulphide BaZrS_(3).Under large compressive strains,BaZrS_(3)can be stabilized into a unique supertetragonal phase with an extraordinary polarization of 67.16μC/cm^(2),which is even stronger than that of conventional oxide ferroelectrics.Excitingly,the supertetragonal BaZrS_(3)exhibits a direct narrow band gap of 1.2 eV and excellent electronic properties.Based on the chemical bonding analysis,we attribute the formation of supertetragonal phase to charge re-ordering in which theπbond overlap along the long〈Zr-S〉bond completely vanishes and the antibonding states of theσbond appear below the Fermi level.Our work provides a conceptual strategy for designing new ferroelectrics for electronic and photovoltaic applications.展开更多
基金supported primarily by the National Key Research and Development Program of China(2018YFE0208500)the Major Research Plan of the National Natural Science Foundation of China(91963206)+4 种基金the National Natural Science Foundation of China(U1508202,51627810,51972164)the Natural Science Foundation of Jiangsu Province(SBK2018022120)the open fund of Wuhan National Laboratory for Optoelectronics(2018WNLOKF020)the open fund of Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies(EEST2018-1)the civil aerospace technology preliminary research project of the State Administration of Science,Technology and Industry for National Defense。
文摘Developing highly active,cost-effective,and environmental friendly oxygen evolution reaction(OER)electrocatalysts facilitates various(photo)electrochemical processes.In this work,Fe3N nanoparticles encapsulated into N-doped graphene nanoshells(Fe_(3)N@NG)as OER electrocatalysts in alkaline media were reported.Both the experimental and theoretical comparison between Fe_(3) N@NG and Fe_(3)N/NG,specifically including in situ Mossbauer analyses,demonstrated that the NG nanoshells improved interfacial electron transfer process from Fe_(3)N to NG to form high-valence Fe^(4+)ions(Fe^(4+)@NG),thus modifying electronic properties of the outer NG shells and subsequently electron transfer from oxygen intermediate to NG nanoshells for OER catalytic process.Meanwhile,the NG nanoshells also protected Fe-based cores from forming OER inactive and insulated Fe_(2)O_(3),leading to high OER stability.As a result,the as-formed Fe^(4+)@NG shows one of the highest electrocatalytic efficiency among reported Fe-based OER electrocatalysts,which can as well highly improve the photoelectrochemical water oxidation when used as the cocatalysts for the Fe_(2)O_(3) nanoarray photoanode.
基金the National Natural Science Foundation of China(81871043 and 82071494)the National Science and Technology Major Project of China(2018ZX09201017 and 2018ZX09201018)the 1.3.5 Project for Disciplines of Excellence,West China Hospital,Sichuan University(ZYGD18024).
文摘Drug-associated reward memories are conducive to intense craving and often trigger relapse.Simvastatin has been shown to regulate lipids that are involved in memory formation but its influence on other cognitive processes is elusive.Here,we used a mass spectrometry-based lipidomic method to evaluate the impact of simvastatin on the mouse brain in a cocaine-induced reinstatement paradigm.We found that simvastatin blocked the reinstatement of cocaine-induced conditioned place preference(CPP)without affecting CPP acquisition.Specifically,only simvastatin administered during extinction prevented cocaine-primed reinstatement.Global lipidome analysis showed that the nucleus accumbens was the region with the greatest degree of change caused by simvastatin.The metabolism of fatty-acids,phospholipids,and triacylglycerol was profoundly affected.Simvastatin reversed most of the effects on phospholipids induced by cocaine.The correlation matrix showed that cocaine and simvastatin significantly reshaped the lipid metabolic pathways in specific brain regions.Furthermore,simvastatin almost reversed all changes in the fatty acyl profile and unsaturation caused by cocaine.In summary,pre-extinction treatment with simvastatin facilitates cocaine extinction and prevents cocaine relapse with brain lipidome remodeling.
基金supported in by the National Natural Science Foundation of China(No.41776089)the Basic Scientific Fund for National Public Research Institutes of China(Nos.2017S03 and 2016S03)
文摘Based on the measurement of major and trace elements in suspended sediments in the low reaches of the Changjiang River during throughout a whole hydrologic year, the origins, seasonal variations, and fluxes of multielements and the human impacts on multielements transport processes have been analyzed along with the influence of weathering in the Changjiang River basin. The results show that most element contents were high in both autumn and winter and low in summer, which was largely caused by the dilution of discharge. Weathering detritus in the Changjiang River basin is the main source of most elements in suspended sediments. However, riverine pollution could bring more loadings of Cd, Pb, As and Zn into river water than it did a few decades ago. The annual average fluxes of Cd, Pb and Zn, which are major contamination elements, to the sea were 179 ± 21 tons/year, 7810 ± 675 tons/year, and 12,000 ± 1320 tons/year,respectively, in which approximately 8.7%, 11.9% and 2.7% of their loadings, respectively,were contributed by pollution inputs. Element exports mainly occurred in the summer(44.4%–57.4%) in the lower part of the Changjiang River. A general relationship between sediment retention and element content suggests a positive feedback mechanism for the decreased number of particles, in which element riverine loadings are reduced due to the enhanced trapping effect by the Three Gorges Dam(TGD). Compared to those in 1980,current element shares of the Changjiang River compared to the global budget have declined due to the construction of the TGD.
基金supported by the National Key R&D Program of China(2019YFD0900200).
文摘This study investigated the effects of hydroxyproline(Hyp)and vitamin C(VC)addition to practical diet on growth and flesh quality of Pacific white shrimp(Litopenaeus vannamei)cultured in low salinity water.The control diet was formulated to contain 200 g/kg fish meal(FM20),and then 14 g/kg coated hydroxyproline(50%)(FM20H),2 g/kg L-ascorbyl-2-phosphate(38%)(FM20C)and their combination(FM20HC)were added to the control diet to form four isoproteic(41.6%)and isolipidic(6.7%)diets.Pacific white shrimp with initial body weight of(1.50±0.05)g were fed the above four diets in low salinity water(salinity 1‰)for 8 weeks.The results showed that the combined supplementation of Hyp and VC(FM20HC)increased the weight gain by 13.4%,and decreased the feed conversion ratio by 0.18(P<0.05),while the individual supplementation(FM20H and FM20C groups)just numerically promoted the growth(P>0.05).In addition,the FM20HC group also showed higher protein and lipid retention than the FM20 group(P<0.05).In flesh quality,the supple-mentation of Hyp(FM20H)increased total collagen and heat-soluble collagen contents,flesh chewiness and free flavor amino acids contents(P<0.05).The supplementation of vC(FM20C)increased the contents of total collagen,heat-insoluble collagen and free flavor amino acids,and decreased flesh lactic acid,malondialdehyde contents and steaming loss(P<0.05).The combined supplementation of Hyp and VC(FM20HC)showed higher total collagen and heat-insoluble collagen contents than the individual supplementation(FM20H and FM20C)(P<0.05),and the myofiber density,flesh hardness and shear force in the FM20HC group were also significantly higher than those in the control(P<0.05).In summary,the combined supplementation of hydroxyproline and vc in practical diet with fishmeal content of 200 g/kg significantly improved the growth performance and flesh quality of L.vannamei cultured in low salinity water.
基金NSFC of China,Grant/Award Numbers:52072059,11774044Foundation of Sichuan Excellent Young Talents,Grant/Award Number:2021JDJQ0015+1 种基金Fundamental Research Funds for the Central Universities,Grant/Award Number:ZYGX2020J023ARC Future Fellowship,Grant/Award Number:FT160100205。
文摘Layered two-dimensional(2D)materials have garnered marvelous attention in diverse fields,including sensors,capacitors,nanocomposites and transistors,owing to their distinctive structural morphologies and superior physicochemical properties.Recently,layered quasi-2D materials,especially layered bismuth oxyselenide(Bi2O2Se),are of particular interest,because of their different interlayer interactions from other layered 2D materials.On this basis,this material offers richer and more intriguing physics,including high electron mobility,sizeable bandgap,and remarkable thermal and chemical durability,rendering it an utterly prospective contender for use in advanced electronic and optoelectronic applications.Herein,this article reviews the recent advances related with Bi2O2Se.Initially,its structural characterization,band structure,and basic properties are briefly introduced.Further,the synthetic strategies for the preparation of Bi_(2)O_(2)Se are presented.Furthermore,the diverse applications of Bi2O2Se in the field of electronics and optoelectronics,photocatalytic,solar cells and sensing were summarized in detail.Ultimately,the challenges and future perspectives of Bi2O2Se are included.
基金supported by the National Natural Science Foundation of China(No.52373316,22075298).
文摘To address the critical challenge of balancing ultralow dielectric constant(k)with low coefficient of thermal expansion(CTE)in high-frequency electronic applications,this study develops a series of tri-armed benzocyclobutene(BCB)-based resins via rational molecular design.Five functional monomers(Ph-BCB,Ph-ene-BCB,Ph-yne-BCB,TPA-yne-BCB,TPB-yne-BCB)were synthesized through Suzuki,Heck,and Sonogashira coupling reactions,followed by thermal curing to form crosslinked polymers.The introduction of branched architectures and rigid conjugated cores effectively enhanced free volume fraction while suppressing molecular chain mobility,achieving synergistic optimization of dielectric and thermomechanical properties.The cured resins exhibited exceptional performance:dielectric constants as low as 1.83(TPA-yne-BCB)at 1 kHz,dielectric loss below 0.0015,and CTE values ranging from 19.23–34.63 ppm℃^(−1),closely matching copper(16 ppm℃^(-1)).The SAXS and WAXS analyses confirmed that enlarged free volume and reduced polarization from optimized topology were key to low-k performance.Additionally,the materials demonstrated outstanding thermal stability(5%weight loss>500℃),high mechanical strength(elastic modulus up to 10 GPa),and hydrophobicity(water absorption<2%).This work provides a groundbreaking strategy for designing high-performance dielectric materials for 5G millimeterwave packaging,flexible electronics,and 3D heterogeneous integration.
基金Haiyan Xiao was supported by the NSAF Joint Foundation of China(Grant No.U1930120)Liang Qiao was supported by National Natural Science Foundation of China(Grant No.11774044,52072059)+1 种基金Zhibin Gao acknowledges the financial support from MOE tier 1 funding of NUS Faculty of Science,Singapore(Grant No.R-144-000-402-114)The theoretical calculations are performed using the supercomputer resources at TianHe-1 located at National Supercomputer Center in Tianjin.
文摘Band degeneracy is effective in optimizing the power factors of thermoelectric(TE)materials by enhancing the Seebeck coefficients.In this study,we demonstrate this effect in model systems of layered oxyselenide family by the density functional theory(DFT)combined with semi-classical Boltzmann transport theory.TE transport performance of layered LaCuOSe and BiCuOSe are fully compared.The results show that due to the larger electrical conductivities caused by longer electron relaxation times,the n-type systems show better TE performance than p-type systems for both LaCuOSe and BiCuOSe.Besides,the conduction band degeneracy of LaCuOSe leads to a larger Seebeck coefficient and a higher optimal carrier concentration than n-type BiCuOSe,and thus a higher power factor.The optimal figure of merit(ZT)value of 1.46 for n-type LaCuOSe is 22%larger than that of 1.2 for n-type BiCuOSe.This study highlights the potential of wide band gap material LaCuOSe for highly efficient TE applications,and demonstrates that inducing band degeneracy by cations substitution is an effective way to enhance the TE performance of layered oxyselenides.
基金National Natural Science Foundation of China,Grant/Award Numbers:52373316,22075298Beijing Municipal Natural Science Foundation,Grant/Award Number:2212053。
文摘The high curing temperatures required for traditional benzocyclobutene(BCB)materials have posed limitations on their applicability in high-temperature-sensitivefields.To address this challenge,our work focuses on the synthesis of a novel tetraphenylethylene(TPE)-functionalized BCB monomer,TPE–BCB,achieved through the introduction of an ether bond onto the BCB’s four-membered ring via Williamson reaction.TPE–BCB demonstrates remarkable low-temperature curing properties,characterized by a ring-opening peak temperature of 190◦C,representing a reduction of 60◦C compared to conventional BCBs.Fully cured TPE–BCB resins exhibit exceptional dielectric and mechanical properties,coupled with minimal water absorption.Additionally,the incorporation of TPE with aggregation-induced emission characteristics enhances the resins’luminescence and photolithographic capabilities.Notably,our TPE–BCB resins achieve impressive photolithography performance with a resolution ratio of up to 10μm.In contrast to conventional BCB-functionalized resins,TPE–BCB offers the dual advantage of low-temperature curing and luminescence.This development marks a significant step in the advance-ment of low-temperature curing BCB materials and serves as a pioneering example in the realm of multilayer wafer bonding materials.
基金This work was supported by the National Natural Science Foundation of China(No.81770021)the postdoctoral program(No.2018M641749).
文摘To the Editor:Bronchial asthma is a respiratory disease with pathological features that mainly comprise changes in airway inflammation,airway remodeling,and airway hyperresponsiveness.
基金supported by the National Natural Science Foundation of China(Grant Nos.52072059,and 11774044)supported by the Joint Funds of the National Natural Science Foundation of China(Grant No.U1930120)。
文摘Over the past century,ferroelectricity has offered exciting opportunities for fundamental research and device applications.However,most of the discovered excellent ferroelectrics are oxide materials with large band gaps,limiting their potential for optoelectronics applications.Here using first-principles calculations we identify a new narrow-gap ferroelectric beyond oxides,i.e.,ferroelectric perovskite sulphide BaZrS_(3).Under large compressive strains,BaZrS_(3)can be stabilized into a unique supertetragonal phase with an extraordinary polarization of 67.16μC/cm^(2),which is even stronger than that of conventional oxide ferroelectrics.Excitingly,the supertetragonal BaZrS_(3)exhibits a direct narrow band gap of 1.2 eV and excellent electronic properties.Based on the chemical bonding analysis,we attribute the formation of supertetragonal phase to charge re-ordering in which theπbond overlap along the long〈Zr-S〉bond completely vanishes and the antibonding states of theσbond appear below the Fermi level.Our work provides a conceptual strategy for designing new ferroelectrics for electronic and photovoltaic applications.
