The Cs_(2)NaInCl_(6) double perovskite is one of the most promising lead-free perovskites due to its exceptional stability and straightforward synthesis.However,it faces challenges related to inefficient photoluminesc...The Cs_(2)NaInCl_(6) double perovskite is one of the most promising lead-free perovskites due to its exceptional stability and straightforward synthesis.However,it faces challenges related to inefficient photoluminescence.Doping and high pressure are employed to tailor the optical properties of Cs_(2)NaInCl_(6).Herein,Sb^(3+)doped Cs_(2)NaInCl_(6)(Sb^(3+):Cs_(2)NaInCl_(6)) was synthesized and it exhibits blue emission with a photoluminescence quantum yield of up to 37.3%.Further,by employing pressure tuning,a blue stable emission under a very wide range from 2.7 GPa to 9.8 GPa is realized in Sb^(3+):Cs_(2)NaInCl_(6).Subsequently,the emission intensity of Sb^(3+):Cs_(2)NaInCl_(6) experiences a significant increase(3.3 times)at 19.0 GPa.It is revealed that the pressure-induced distinct emissions can be attributed to the carrier self-trapping and detrapping between Cs_(2)NaInCl_(6) and Sb^(3+).Notably,the lattice compression in the cubic phase inevitably modifies the band gap of Sb^(3+):Cs_(2)NaInCl_(6).Our findings provide valuable insights into effects of the high pressure in further boosting unique emission characteristics but also offer promising opportunities for development of doped double perovskites with enhanced optical functionalities.展开更多
The recent discoveries of near-room-temperature superconductivity in clathrate hydrides present compelling evidence for the reliability of theory-orientated conventional superconductivity.Nevertheless,the harsh pressu...The recent discoveries of near-room-temperature superconductivity in clathrate hydrides present compelling evidence for the reliability of theory-orientated conventional superconductivity.Nevertheless,the harsh pressure conditions required to maintain such high T_(c)limit their practical applications.To address this challenge,we conducted extensive first-principles calculations to investigate the doping effect of the recently synthesized LaB_(8)clathrate,intending to design high-temperature superconductors at ambient pressure.Our results demonstrate that these clathrates are highly promising for high-temperature superconductivity owing to the coexistence of rigid boron covalent networks and the tunable density of states at the Fermi level.Remarkably,the predicted T_(c)of BaB_(8)could reach 62 K at ambient pressure,suggesting a significant improvement over the calculated T_(c)of 14 K in LaB_(8).Moreover,further calculations of the formation enthalpies suggest that BaB_(8)could be potentially synthesized under high-temperature and high-pressure conditions.These findings highlight the potential of doped boron clathrates as promising superconductors and provide valuable insights into the design of light-element clathrate superconductors.展开更多
We present a mechanically tunable broadband terahertz(THz) modulator based on the high-aligned Ni nanowire(NW)arrays. The modulator is a sandwich structure consisting of two polydimethylsiloxane layers and a central l...We present a mechanically tunable broadband terahertz(THz) modulator based on the high-aligned Ni nanowire(NW)arrays. The modulator is a sandwich structure consisting of two polydimethylsiloxane layers and a central layer of highaligned Ni NW arrays. Our experimental measurements reveal the transmittance of THz wave can be effectively modulated by mechanical stretching. The NW density in arrays increases with the strain increasing, which induced an enhancement in the absorption of THz wave. When the strain increases from 0 to 6.5%, a linear relationship is observed for the variation of modulation depth(MD) of THz wave regarding the strain, and the modulated range is from 0 to 85% in a frequency range from 0.3 THz to 1.8 THz. Moreover, the detectable MD is about 15% regarding the 1% strain change resolution. This flexible Ni NW-based modulator can be promised many applications, such as remote strain sensing, and wearable devices.展开更多
Improving the accuracy of shape sensors based on multicore fibers(MCFs)is challenging but of great importance for real-time 3D shape detection,especially in visually inaccessible areas.In this work,a novel approach is...Improving the accuracy of shape sensors based on multicore fibers(MCFs)is challenging but of great importance for real-time 3D shape detection,especially in visually inaccessible areas.In this work,a novel approach is proposed to improve MCF shape sensor accuracy using an ultraviolet transparent liquid mediated fiber Bragg grating(FBG)inscription technique and a twist-isolating packaging method.A newly developed UV index matching liquid(UV-IML)is used to generate uniform light field at all the MCF cores,enabling FBG inscription with high accuracy.Additionally,a new stress fully released(SFR)packaging method is implemented to isolate the sensor from any external twists.The MCF shape sensor shows a maximum relative error of only 3.33%and the lowest reported relative sensitivity error of 1.11%cm^(-1).Moreover,a real-time 3D shape sensing system with a response frequency larger than 30 Hz is constructed using the unique MCF shape sensor.The highly accurate real-time 3D shape sensing results indicate potential applications for in vivo shape estimation of endoscopies and soft robots.展开更多
The polarization and domain behavior on the surface of a ferroelectric material are significantly affected by the screening processes [1-12].Recently,there has been a notable increase in the theoretical calculations a...The polarization and domain behavior on the surface of a ferroelectric material are significantly affected by the screening processes [1-12].Recently,there has been a notable increase in the theoretical calculations and experiments investigating the dynamics of polarization and domain behaviors coexisting in phase transitions of ferroelectric materials.展开更多
Formic acid oxidation(FAO)is a typical anode reaction in fuel cells that can be facilitated by modulating its direct and indirect reaction pathways.Herein,PtAu bimetallic nanoparticles loaded onto Co and N co-doping c...Formic acid oxidation(FAO)is a typical anode reaction in fuel cells that can be facilitated by modulating its direct and indirect reaction pathways.Herein,PtAu bimetallic nanoparticles loaded onto Co and N co-doping carbon nanoframes(CoNC NFs)were designed to improve the selectivity of the direct reaction pathway for efficient FAO.Based on these subtle nanomaterials,the influences of elemental composition and carbon-support materials on the two pathways of FAO were investigated in detail.The results of fuel cell tests verified that the appropriate amount of Au in PtAu/CoNC can promote a direct reaction pathway for FAO,which is crucial for enhancing the oxidation efficiency of formic acid.In particular,the obtained PtAu/CoNC with an optimal Pt/Au atomic ratio of 1:1(PtAu/CoNC-3)manifests the best catalytic performance among the analogous obtained Pt-based electrocatalysts.The FAO mass activity of the PtAu/CoNC-3 sample reached 0.88 A·mg_(Pt)^(-1),which is 26.0 times higher than that of Pt/C.The results of first-principles calculation and CO stripping jointly demonstrate that the CO adsorption of PtAu/CoNC is considerably lower than that of Pt/CoNC and PtAu/C,which indicates that the synergistic effect of Pt,Au,and CoNC NFs is critical for the resistance of Pt to CO poisoning.This work is of great significance for a deeper understanding of the oxidation mechanism of formic acid and provides a feasible and promising strategy for enhancing the catalytic performance of the catalyst by improving the direct reaction pathway for FAO.展开更多
Controlling oxygen redox reactions in transition metal oxides offers an attractive route to tune their physical properties;a topotactic structural transformation from their parent phases effectively modifies the elect...Controlling oxygen redox reactions in transition metal oxides offers an attractive route to tune their physical properties;a topotactic structural transformation from their parent phases effectively modifies the electronic state. In this work, infinitelayered SrFeO_(2) thin films were produced from brownmillerite SrFeO_(2.5) via low-temperature hydro-reduction. After the structural transition, their out-of-plane lattice constants dramatically shrank by 12%;tensilely strained samples exhibited metallic character, whereas the compressively strained ones maintained the insulating behavior of their bulk form. According to X-ray linear dichroism results, this strain-mediated electronic anisotropy may be attributed to electron redistribution within degenerated orbitals. This suggests a possible mechanism for the metallic conductivity of infinite-layered SrFeO_(2), giving a hint for understanding emergent quantum phenomena, such as the recently discovered superconductivity in nickelates, and stimulating various applications, including in ionic conductivity and oxygen catalysis.展开更多
The ultrafast laser-excited magnetization dynamics of ferromagnetic (FM) La0.67Sr0.33MnO3 (LSMO) thin films with BiFeO3 (BFO) coating layers grown by laser molecular beam epitaxy are investigated using the optic...The ultrafast laser-excited magnetization dynamics of ferromagnetic (FM) La0.67Sr0.33MnO3 (LSMO) thin films with BiFeO3 (BFO) coating layers grown by laser molecular beam epitaxy are investigated using the optical pump-probe technique. Uniform magnetization precessions are observed in the films under an applied external magnetic field by measuring the time-resolved magneto-optical Kerr effect. The magnetization precession frequencies of the LSMO thin films with the BFO coating layers are lower than those of uncoated LSMO films, which is attributed to the suppression of the anisotropy field induced by the exchange interaction at the interface between the antiferromagnetic order of BFO and the FM order of LSMO.展开更多
Optical vortices(OVs) with unique square symmetry are widely used in various applications including particle manipulation,microscopy, and image processing. However, the undesired higher-order foci introduced by the co...Optical vortices(OVs) with unique square symmetry are widely used in various applications including particle manipulation,microscopy, and image processing. However, the undesired higher-order foci introduced by the conventional vortex lens such as square spiral zone plates(SSZPs) may lead to additional artifacts and thus degrade contrast sensitivity. In this endeavor, herein,we propose a methodology to combine the merit of SSZPs and the advantage of Gabor zone plates(GZPs) in establishing a specific single optical element, termed binary single focused square spiral zone plates(BSSZPs). In contrast to the abrupt transitions of the SSZPs, our central idea aims to realize the sinusoidal transmittance along the radial direction of SSZPs by a series of randomly distributed annulus-quadrangle-shaped nanometer structure apertures. The innovative design can simultaneously generate OVs with unique square symmetry, and eliminate the interference of higher-order foci along the propagation direction. Guided by our theoretical predication, the focusing property of such optics was further experimentally demonstrated.These findings are expected to direct new avenue towards improving the performance of optical image processing and alignment system.展开更多
We investigated the effects of oxygen vacancies on the structural, magnetic, and transport properties of Lal-xSrxMnO3 (x=0.1, 0.2, 0.33, 0.4, and 0.5) grown around a critical point (without/with oxygen vacancies) ...We investigated the effects of oxygen vacancies on the structural, magnetic, and transport properties of Lal-xSrxMnO3 (x=0.1, 0.2, 0.33, 0.4, and 0.5) grown around a critical point (without/with oxygen vacancies) under low oxygen pressure (10 Pa) and high oxygen pressure (40 Pa). We found that all films exhibit ferromagnetic behavior below the magnetic critical temperature, and that the films grown under low oxygen pressures have degraded magnetic properties with lower Curie temperatures and smaller magnetic moments. These results show that in epitaxial La1-xSrxMnO3 thin films, the magnetic and transport properties are very sensitive to doping concentration and oxygen vacancies. Phase diagrams of the films based on the doping concentration and oxygen vacancies were plotted and discussed.展开更多
As an alternative electrode material,transition metal oxides are promising candidates due to multivalent nature and oxygen vacancies present in the structure with facilitate redox reactions.The aim of this study is to...As an alternative electrode material,transition metal oxides are promising candidates due to multivalent nature and oxygen vacancies present in the structure with facilitate redox reactions.The aim of this study is to explore the intrinsic mechanism of oxygen evolution reaction(OER)using two-dimensional thin film La1-xSrxCoO3 electrode as a model.Herein,we report a planar two-dimensional model La1-xSrxCoO3 electrode grown on a Nb-SrTiO3 single-crystal substrate via pulsed laser deposition.The two-dimensional La1-xSrxCoO3 films offer different oxygen evolution activities at different pH electrolyte solutions.The mechanisms behind the variations of the oxygen evolution activity were discussed after comparing the oxygen evolution activity before and after treatments of the electrodes and measurements by various test methods.The results of this study offer a promising,low-cost electrode material for the efficient OER and a sustainable production of hydrogen fuel.展开更多
Ferroelectric tunnel junction(FTJ)has attracted considerable attention for its potential applications in nonvolatile memory and neuromorphic computing.However,the experimental exploration of FTJs with high ON/OFF rati...Ferroelectric tunnel junction(FTJ)has attracted considerable attention for its potential applications in nonvolatile memory and neuromorphic computing.However,the experimental exploration of FTJs with high ON/OFF ratios is a challenging task due to the vast search space comprising of ferroelectric and electrode materials,fabrication methods and conditions and so on.Here,machine learning(ML)is demonstrated to be an effective tool to guide the experimental search of FTJs with high ON/OFF ratios.A dataset consisting of 152 FTJ samples with nine features and one target attribute(i.e.,ON/OFF ratio)is established for ML modeling.Among various ML models,the gradient boosting classification model achieves the highest prediction accuracy.Combining the feature importance analysis based on this model with the association rule mining,it is extracted that the utilizations of{graphene/graphite(Gra)(top),LaNiO_(3)(LNO)(bottom)}and{Gra(top),Ca_(0.96)Ce_(0.04)MnO_(3)(CCMO)(bottom)}electrode pairs are likely to result in high ON/OFF ratios in FTJs.Moreover,two previously unexplored FTJs:Gra/BaTiO_(3)(BTO)/LNO and Gra/BTO/CCMO,are predicted to achieve ON/OFF ratios higher than 1000.Guided by the ML predictions,the Gra/BTO/LNO and Gra/BTO/CCMO FTJs are experimentally fabricated,which unsurprisingly exhibit≥1000 ON/OFF ratios(~8540 and~7890,respectively).This study demonstrates a new paradigm of developing high-performance FTJs by using ML.展开更多
BiFeO_3 (BFO) thin films with BaTiO_3 (BTO) or SrTiO_3 (STO) as buffer layer were epitaxially grown on SrRuO_3-covered SrTiO_3 substrates. X-ray diffraction measurements show that the BTO buffer causes tensile strain ...BiFeO_3 (BFO) thin films with BaTiO_3 (BTO) or SrTiO_3 (STO) as buffer layer were epitaxially grown on SrRuO_3-covered SrTiO_3 substrates. X-ray diffraction measurements show that the BTO buffer causes tensile strain in the BFO films, whereas the STO buffer causes compressive strain. Different ferroelectric domain structures caused by these two strain statuses are revealed by piezoelectric force microscopy. Electrical and magnetical measurements show that the tensile-strained BFO/BTO samples have reduced leakage current and large ferroelectric polarization and magnetization, compared with compressively strained BFO/STO. These results demonstrate that the electrical and magnetical properties of BFO thin films can be artificially modified by using a buffer layer.展开更多
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1400200 and2021YFA0718701)the National Natural Science Foundation of China(Grant Nos.U2032127,11904322,12104411,12174347)+4 种基金the Natural Science Foundation of Henan province of China(Grant No.202300410356)the China Postdoctoral Science Foundation(Grant Nos.2019M652560 and 2020M682326)the CAS Interdisciplinary Innovation Team(Grant No.JCTD-2019-01)the Postdoctoral Research Grant in Henan Province(Grant No.1902013)the Science Foundation for Highlevel Talents of Wuyi University(Grant No.2021AL019)。
文摘The Cs_(2)NaInCl_(6) double perovskite is one of the most promising lead-free perovskites due to its exceptional stability and straightforward synthesis.However,it faces challenges related to inefficient photoluminescence.Doping and high pressure are employed to tailor the optical properties of Cs_(2)NaInCl_(6).Herein,Sb^(3+)doped Cs_(2)NaInCl_(6)(Sb^(3+):Cs_(2)NaInCl_(6)) was synthesized and it exhibits blue emission with a photoluminescence quantum yield of up to 37.3%.Further,by employing pressure tuning,a blue stable emission under a very wide range from 2.7 GPa to 9.8 GPa is realized in Sb^(3+):Cs_(2)NaInCl_(6).Subsequently,the emission intensity of Sb^(3+):Cs_(2)NaInCl_(6) experiences a significant increase(3.3 times)at 19.0 GPa.It is revealed that the pressure-induced distinct emissions can be attributed to the carrier self-trapping and detrapping between Cs_(2)NaInCl_(6) and Sb^(3+).Notably,the lattice compression in the cubic phase inevitably modifies the band gap of Sb^(3+):Cs_(2)NaInCl_(6).Our findings provide valuable insights into effects of the high pressure in further boosting unique emission characteristics but also offer promising opportunities for development of doped double perovskites with enhanced optical functionalities.
基金supported by the Theoretical Physics Research Project of the National Natural Science Foundation of China(Grant No.12247177)the National Natural Science Foundation of China(Grant No.12004340)+1 种基金Zhengzhou Universitysupported by the National Supercomputing Centre in Zhengzhou。
文摘The recent discoveries of near-room-temperature superconductivity in clathrate hydrides present compelling evidence for the reliability of theory-orientated conventional superconductivity.Nevertheless,the harsh pressure conditions required to maintain such high T_(c)limit their practical applications.To address this challenge,we conducted extensive first-principles calculations to investigate the doping effect of the recently synthesized LaB_(8)clathrate,intending to design high-temperature superconductors at ambient pressure.Our results demonstrate that these clathrates are highly promising for high-temperature superconductivity owing to the coexistence of rigid boron covalent networks and the tunable density of states at the Fermi level.Remarkably,the predicted T_(c)of BaB_(8)could reach 62 K at ambient pressure,suggesting a significant improvement over the calculated T_(c)of 14 K in LaB_(8).Moreover,further calculations of the formation enthalpies suggest that BaB_(8)could be potentially synthesized under high-temperature and high-pressure conditions.These findings highlight the potential of doped boron clathrates as promising superconductors and provide valuable insights into the design of light-element clathrate superconductors.
基金Project supported by the National Natural Science Foundation of China (Grant No. 62075245)Xinjiang Uygur Autonomous Region University Scientific Research Foundation (Grant No. XJEDU2018I021)。
文摘We present a mechanically tunable broadband terahertz(THz) modulator based on the high-aligned Ni nanowire(NW)arrays. The modulator is a sandwich structure consisting of two polydimethylsiloxane layers and a central layer of highaligned Ni NW arrays. Our experimental measurements reveal the transmittance of THz wave can be effectively modulated by mechanical stretching. The NW density in arrays increases with the strain increasing, which induced an enhancement in the absorption of THz wave. When the strain increases from 0 to 6.5%, a linear relationship is observed for the variation of modulation depth(MD) of THz wave regarding the strain, and the modulated range is from 0 to 85% in a frequency range from 0.3 THz to 1.8 THz. Moreover, the detectable MD is about 15% regarding the 1% strain change resolution. This flexible Ni NW-based modulator can be promised many applications, such as remote strain sensing, and wearable devices.
基金Major Scientific Research Project of Zhejiang Laboratory(No.2019MC0AD02)Innovation Project of Zhejiang Laboratory(No.2022MG0AL03)+1 种基金National Science Foundation of China(Nos.62204230,62020106002,T2293750,62205306,92250304)National Key Research and Development Program of China(2021YFC2401403)。
文摘Improving the accuracy of shape sensors based on multicore fibers(MCFs)is challenging but of great importance for real-time 3D shape detection,especially in visually inaccessible areas.In this work,a novel approach is proposed to improve MCF shape sensor accuracy using an ultraviolet transparent liquid mediated fiber Bragg grating(FBG)inscription technique and a twist-isolating packaging method.A newly developed UV index matching liquid(UV-IML)is used to generate uniform light field at all the MCF cores,enabling FBG inscription with high accuracy.Additionally,a new stress fully released(SFR)packaging method is implemented to isolate the sensor from any external twists.The MCF shape sensor shows a maximum relative error of only 3.33%and the lowest reported relative sensitivity error of 1.11%cm^(-1).Moreover,a real-time 3D shape sensing system with a response frequency larger than 30 Hz is constructed using the unique MCF shape sensor.The highly accurate real-time 3D shape sensing results indicate potential applications for in vivo shape estimation of endoscopies and soft robots.
基金supported by the National Natural Science Foundation of China(Grant No.11574365)
文摘The polarization and domain behavior on the surface of a ferroelectric material are significantly affected by the screening processes [1-12].Recently,there has been a notable increase in the theoretical calculations and experiments investigating the dynamics of polarization and domain behaviors coexisting in phase transitions of ferroelectric materials.
基金support from the National Natural Science Foundation of China(Nos.51801188,12034002,and 51971025)the China Postdoctoral Science Foundation(No.2018M632792)+3 种基金program for the Innovation Team of Science and Technology in University of Henan(No.20IRTSTHN014)Excellent Youth Foundation of Henan Scientific Committee(No.202300410356)the CAS Interdisciplinary Innovation Team(No.JCTD-2019-01)Beijing Natural Science Foundation(No.2204085)。
文摘Formic acid oxidation(FAO)is a typical anode reaction in fuel cells that can be facilitated by modulating its direct and indirect reaction pathways.Herein,PtAu bimetallic nanoparticles loaded onto Co and N co-doping carbon nanoframes(CoNC NFs)were designed to improve the selectivity of the direct reaction pathway for efficient FAO.Based on these subtle nanomaterials,the influences of elemental composition and carbon-support materials on the two pathways of FAO were investigated in detail.The results of fuel cell tests verified that the appropriate amount of Au in PtAu/CoNC can promote a direct reaction pathway for FAO,which is crucial for enhancing the oxidation efficiency of formic acid.In particular,the obtained PtAu/CoNC with an optimal Pt/Au atomic ratio of 1:1(PtAu/CoNC-3)manifests the best catalytic performance among the analogous obtained Pt-based electrocatalysts.The FAO mass activity of the PtAu/CoNC-3 sample reached 0.88 A·mg_(Pt)^(-1),which is 26.0 times higher than that of Pt/C.The results of first-principles calculation and CO stripping jointly demonstrate that the CO adsorption of PtAu/CoNC is considerably lower than that of Pt/CoNC and PtAu/C,which indicates that the synergistic effect of Pt,Au,and CoNC NFs is critical for the resistance of Pt to CO poisoning.This work is of great significance for a deeper understanding of the oxidation mechanism of formic acid and provides a feasible and promising strategy for enhancing the catalytic performance of the catalyst by improving the direct reaction pathway for FAO.
基金supported by the National Key Basic Research Program of China(Grant Nos.2020YFA0309100,and 2019YFA0308500)the Program for the Innovation Team of Science and Technology in University of Henan(Grant No.20IRTSTHN014)+4 种基金the Excellent Youth Foundation of He’nan Scientific Committee(Grant No.202300410356)the National Natural Science Foundation of China(Grant No.11974390)the Beijing Nova Program of Science and Technology(Grant No.Z191100001119112)the Beijing Natural Science Foundation(Grant No.2202060)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB33030200)。
文摘Controlling oxygen redox reactions in transition metal oxides offers an attractive route to tune their physical properties;a topotactic structural transformation from their parent phases effectively modifies the electronic state. In this work, infinitelayered SrFeO_(2) thin films were produced from brownmillerite SrFeO_(2.5) via low-temperature hydro-reduction. After the structural transition, their out-of-plane lattice constants dramatically shrank by 12%;tensilely strained samples exhibited metallic character, whereas the compressively strained ones maintained the insulating behavior of their bulk form. According to X-ray linear dichroism results, this strain-mediated electronic anisotropy may be attributed to electron redistribution within degenerated orbitals. This suggests a possible mechanism for the metallic conductivity of infinite-layered SrFeO_(2), giving a hint for understanding emergent quantum phenomena, such as the recently discovered superconductivity in nickelates, and stimulating various applications, including in ionic conductivity and oxygen catalysis.
基金supported by the National Key Basic Research Program of China(Grant Nos.2014CB921001,and 2013CB328706)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(GrantNo.QYZDJ-SSW-SLH020)+1 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB07030200)the National Natural Science Foundation of China(Grant Nos.11574365,11474349,11674385,11404380,91436101,and 61275060)
文摘The ultrafast laser-excited magnetization dynamics of ferromagnetic (FM) La0.67Sr0.33MnO3 (LSMO) thin films with BiFeO3 (BFO) coating layers grown by laser molecular beam epitaxy are investigated using the optical pump-probe technique. Uniform magnetization precessions are observed in the films under an applied external magnetic field by measuring the time-resolved magneto-optical Kerr effect. The magnetization precession frequencies of the LSMO thin films with the BFO coating layers are lower than those of uncoated LSMO films, which is attributed to the suppression of the anisotropy field induced by the exchange interaction at the interface between the antiferromagnetic order of BFO and the FM order of LSMO.
基金supported by the National Key Research and Development Program of China (Grant No. 2021YFA1400204)National Natural Science Foundation of China (Grant Nos. 12174350, 11905200, 12105268,11805179, 11905201, and 12174347)+2 种基金Program for Science&Technology Innovation Talents of Henan Province (Grant No. 202102310001)Science and Technology on Plasma Physics Laboratory (Grant No. 6142A04200107)Excellent Youth Foundation of Henan Scientific Committee (Grant No. 202300410356)。
文摘Optical vortices(OVs) with unique square symmetry are widely used in various applications including particle manipulation,microscopy, and image processing. However, the undesired higher-order foci introduced by the conventional vortex lens such as square spiral zone plates(SSZPs) may lead to additional artifacts and thus degrade contrast sensitivity. In this endeavor, herein,we propose a methodology to combine the merit of SSZPs and the advantage of Gabor zone plates(GZPs) in establishing a specific single optical element, termed binary single focused square spiral zone plates(BSSZPs). In contrast to the abrupt transitions of the SSZPs, our central idea aims to realize the sinusoidal transmittance along the radial direction of SSZPs by a series of randomly distributed annulus-quadrangle-shaped nanometer structure apertures. The innovative design can simultaneously generate OVs with unique square symmetry, and eliminate the interference of higher-order foci along the propagation direction. Guided by our theoretical predication, the focusing property of such optics was further experimentally demonstrated.These findings are expected to direct new avenue towards improving the performance of optical image processing and alignment system.
基金supported by the National Key Basic Research Program of China(Grant Nos.2014CB921001,and 2013CB328706)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(GrantNo.QYZDJ-SSW-SLH020)+1 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(GrantNo.XDB07030200)the National Natural Science Foundation of China(Grant Nos.11574365,11474349,11674385,and 11404380)
文摘We investigated the effects of oxygen vacancies on the structural, magnetic, and transport properties of Lal-xSrxMnO3 (x=0.1, 0.2, 0.33, 0.4, and 0.5) grown around a critical point (without/with oxygen vacancies) under low oxygen pressure (10 Pa) and high oxygen pressure (40 Pa). We found that all films exhibit ferromagnetic behavior below the magnetic critical temperature, and that the films grown under low oxygen pressures have degraded magnetic properties with lower Curie temperatures and smaller magnetic moments. These results show that in epitaxial La1-xSrxMnO3 thin films, the magnetic and transport properties are very sensitive to doping concentration and oxygen vacancies. Phase diagrams of the films based on the doping concentration and oxygen vacancies were plotted and discussed.
基金the National Natural Science Foundation of China(Grant Nos.11574365,and 11974099)the Program for the Innovation Team of Science and Technology in University of Henan(Grant No.20IRTSTHN014)。
文摘As an alternative electrode material,transition metal oxides are promising candidates due to multivalent nature and oxygen vacancies present in the structure with facilitate redox reactions.The aim of this study is to explore the intrinsic mechanism of oxygen evolution reaction(OER)using two-dimensional thin film La1-xSrxCoO3 electrode as a model.Herein,we report a planar two-dimensional model La1-xSrxCoO3 electrode grown on a Nb-SrTiO3 single-crystal substrate via pulsed laser deposition.The two-dimensional La1-xSrxCoO3 films offer different oxygen evolution activities at different pH electrolyte solutions.The mechanisms behind the variations of the oxygen evolution activity were discussed after comparing the oxygen evolution activity before and after treatments of the electrodes and measurements by various test methods.The results of this study offer a promising,low-cost electrode material for the efficient OER and a sustainable production of hydrogen fuel.
基金The authors would like to thank the National Natural Science Foundation of China(Nos.92163210,U1932125,52172143,12174347,61874158 and 92164109)Science and Technology Program of GuangZhou(No.2019050001)Natural Science of Guangdong Province(No.2020A1515010996).
文摘Ferroelectric tunnel junction(FTJ)has attracted considerable attention for its potential applications in nonvolatile memory and neuromorphic computing.However,the experimental exploration of FTJs with high ON/OFF ratios is a challenging task due to the vast search space comprising of ferroelectric and electrode materials,fabrication methods and conditions and so on.Here,machine learning(ML)is demonstrated to be an effective tool to guide the experimental search of FTJs with high ON/OFF ratios.A dataset consisting of 152 FTJ samples with nine features and one target attribute(i.e.,ON/OFF ratio)is established for ML modeling.Among various ML models,the gradient boosting classification model achieves the highest prediction accuracy.Combining the feature importance analysis based on this model with the association rule mining,it is extracted that the utilizations of{graphene/graphite(Gra)(top),LaNiO_(3)(LNO)(bottom)}and{Gra(top),Ca_(0.96)Ce_(0.04)MnO_(3)(CCMO)(bottom)}electrode pairs are likely to result in high ON/OFF ratios in FTJs.Moreover,two previously unexplored FTJs:Gra/BaTiO_(3)(BTO)/LNO and Gra/BTO/CCMO,are predicted to achieve ON/OFF ratios higher than 1000.Guided by the ML predictions,the Gra/BTO/LNO and Gra/BTO/CCMO FTJs are experimentally fabricated,which unsurprisingly exhibit≥1000 ON/OFF ratios(~8540 and~7890,respectively).This study demonstrates a new paradigm of developing high-performance FTJs by using ML.
基金supported by the National Key Basic Research Program of China (Grant Nos. 2014CB921002, and 2013CBA01703)the National Natural Science Foundation of China (Grant Nos. 11174355, 11674385, and 11574365)the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07030200)
文摘BiFeO_3 (BFO) thin films with BaTiO_3 (BTO) or SrTiO_3 (STO) as buffer layer were epitaxially grown on SrRuO_3-covered SrTiO_3 substrates. X-ray diffraction measurements show that the BTO buffer causes tensile strain in the BFO films, whereas the STO buffer causes compressive strain. Different ferroelectric domain structures caused by these two strain statuses are revealed by piezoelectric force microscopy. Electrical and magnetical measurements show that the tensile-strained BFO/BTO samples have reduced leakage current and large ferroelectric polarization and magnetization, compared with compressively strained BFO/STO. These results demonstrate that the electrical and magnetical properties of BFO thin films can be artificially modified by using a buffer layer.