Achieving long spin coherence times is crucial for quantum precision measurements,and closed-loop control techniques are often employed to accomplish this goal.Here,we demonstrate the impact of closed-loop feedback co...Achieving long spin coherence times is crucial for quantum precision measurements,and closed-loop control techniques are often employed to accomplish this goal.Here,we demonstrate the impact of closed-loop feedback control on nuclear spin precession in a metastability exchange optical pumping(MEOP)-based polarized^(3)He system.We analyze the effects of feedback theoretically and validate our predictions experimentally.With optimized feedback parameters,the spin coherence time T_(2)is extended by an order of magnitude.When the feedback strength surpasses a critical threshold,robust maser oscillations are spontaneously excited,demonstrating remarkable resistance to environmental noise and maintaining stable oscillation.This proof-of-principle experiment highlights the viability of MEOP-based^(3)He spin oscillators,especially in low-frequency domains.The operational simplicity and easy integration associated with MEOP-based systems make them particularly promising for fast,high-precision magnetic field measurements.展开更多
Hafnia-based ferroelectrics have emerged as promising materials for next-generation nanoelectronics owing to their robust nanoscale properties and compatibility with metal-oxide-semiconductor technology.However,their ...Hafnia-based ferroelectrics have emerged as promising materials for next-generation nanoelectronics owing to their robust nanoscale properties and compatibility with metal-oxide-semiconductor technology.However,their metastable nature remains a key challenge for practical implementation.Utilizing scanning transmission electron microscopy,we investigated the atomic-scale mechanisms governing ferroelectric transitions and the metastability of polar phases in 10-nm-thick Hf_(0.5)Zr_(0.5)O_(2)thin films.Our results demonstrate that oxygen vacancies,coupled with rhombohedral distortions of the cation lattice,facilitate ferroelectric phase transitions and enable robust polar switching through adaptive processes,including cell-by-cell oxygen displacement and domain-wall-mediated nucleation and growth.These findings underscore the pivotal role of oxygen vacancies and lattice distortions in stabilizing polar phases and provide detailed insights into the atomic structures and transition dynamics of polymorphic Hf_(0.5)Zr_(0.5)O_(2-x),thereby advancing its potential for practical device applications.展开更多
A fine-grained metastable dual-phase Fe_(40)Mn_(20)Co_(20)Cr_(15)Si_(5)high entropy alloy(CS-HEA)with excellent strength and ductility was successfully prepared by friction stir processing(FSP).The microstructural and...A fine-grained metastable dual-phase Fe_(40)Mn_(20)Co_(20)Cr_(15)Si_(5)high entropy alloy(CS-HEA)with excellent strength and ductility was successfully prepared by friction stir processing(FSP).The microstructural and mechanical properties of the fine-grained CS-HEA were characterized.The results showed that as-cast shrinkage cavities and elemental segregation were eliminated.The average grain size was refined from 121.1 to 5.4μm.The face-centered cubic phase fraction increased from 23%to 82%.During tensile deformation,dislocation slip dominated at strains ranging from 5%to 17%,followed by transformation induced plasticity(TRIP)from 17%to 26%,and twin induced plasticity(TWIP)from 26%to 37%.The yield strength,ultimate tensile strength,and elongation of the fine-grained CS-HEA were 503 MPa,1120 MPa,and 37%,respectively.The strength-ductility synergy of fine-grained CS-HEA was attributed to the combined effects of TRIP,TWIP,dislocation strengthening,and fine-grained strengthening.展开更多
Laser powder bed fusion(LPBF)is an attractive additive manufacturing technology for preparing high-performance high-entropy alloys(HEAs)engineering components.Unfortunately,the existence of inherent thermal residual s...Laser powder bed fusion(LPBF)is an attractive additive manufacturing technology for preparing high-performance high-entropy alloys(HEAs)engineering components.Unfortunately,the existence of inherent thermal residual stress and non-equilibrium microstructures in the additively manufactured components results in unsatisfactory mechanical properties.Herein,we propose a novel strengthening strategy,namely deep cryogenic treatment(DCT)followed by laser shock peening(LSP),to tailor the microstructures and enhance performances of an LPBF additively manufactured metastable HEA.The post-treatment effects of DCT+LSP on the LPBF-fabricated Fe_(50)Mn_(30)Co_(10)Cr_(10)HEA are evaluated in terms of microstructural modifications,residual stress,and microhardness redistribution,as well as tensile properties.Results indicate that a gradient heterogeneous structure is formed on the as-built sample surface,featuring gradient variations in grain size,martensitic phase content,and dislocation density,due to the grain refinement and martensitic phase transformation under DCT+LSP.The initial tensile residual stress on the surface is fully transformed into compressive stress,achieving a peak of-289 MPa,and the surface microhardness attains a maximum of 380.8 HV.The various strengthening mechanisms of gradient heterogeneous structures,as well as the multiple effects of heterodeformation-induced(HDI)hardening,transformation-induced plasticity(TRIP),and twinning-induced plasticity(TWIP),are responsible for achieving strength-ductility synergy.This work provides a practical pathway and valuable scientific insights for enhancing the mechanical behaviors of additively manufactured metastable HEAs via microstructural engineering.展开更多
As a prototypical high-energy-density reactive material system,metastable intermolecular composites(MICs)have attracted considerable interest owing to their customizable component configurations and interfacial archit...As a prototypical high-energy-density reactive material system,metastable intermolecular composites(MICs)have attracted considerable interest owing to their customizable component configurations and interfacial architectures.Nevertheless,their energy release characteristics are fundamentally constrained by the formation of condensed-phase products with elevated boiling points,thereby diminishing their efficacy in applications requiring rapid pressure generation or shock wave propagation.Herein,we demonstrate a molecular-level fluorination approach that enables oxygen substitution by fluorine within bismuth oxide crystalline frameworks,yielding ternary BixOyFz crystals with atomically precise F/O stoichiometric control through systematic solvent polarity engineering.This energetics system,designed through a multilevel regulation strategy,realizes stepwise redox reactions of Al–F and Al–O during energy release,with the partitioning between these redox pathways being precisely allocable through hierarchical regulation.Furthermore,the pre-ignition reaction(PIR)between BixOyFz and Al2O3(the inert passivation shell of Al)weakens the passivation layer,lowering the ignition threshold.The in situ generation of low-boiling-point AlF3 promotes rapid gas expansion,leading to significantly enhanced pressurization rates and deflagration wave velocities under confinement compared to conventional strategies.To evaluate energy output capabilities and validate potential safety-protection applications,the system successfully achieved instantaneous destruction of SD chips,enabling secure data erasure.This work establishes crystalline lattice fluorination as a generalized materials design strategy to transcend intrinsic limitations of MICs systems in component selection and reaction thermodynamics,providing new paradigms for adaptive energetic architectures and transient microelectromechanical applications.展开更多
White Cyphochilus insulanus beetles,exhibiting both environmental camouflage display and radiative cooling functions,serve as a good prototype for biomimetic fabrication.As inspired,this work presents a femtosecond(fs...White Cyphochilus insulanus beetles,exhibiting both environmental camouflage display and radiative cooling functions,serve as a good prototype for biomimetic fabrication.As inspired,this work presents a femtosecond(fs)laser-based biomimetic fabrication strategy that takes full use of the synthesized radiative cooling nanomaterials for a groundbreaking stimuli-responsive infrared(IR)impressionistic camouflage display.The proposed technique is capable of readily transforming various substrates(quartz glass and metals including Ti,Al,Zr,and W)into self-assembled porous networks(aerogels)consisting of oxygen-vacancy-rich oxide nanoparticles.Surprisingly,the emissions of all as-prepared porous particle-networks in the radiative-cooling long-wavelength infrared(LWIR)band are above 95%,with the SiO_(2) aerogels reaching a maximum of 99.6%.Benefiting from the far-from-equilibrium thermodynamic kinetics,metastable phases of anatase TiO_(2),tetragonal zirconia(t-ZrO_(2)),and monoclinic WO_(3)(Pc)are synthesizable,opening up opportunities for exploring their optical applications.Taking the low-temperature metastable phase WO_(3)(Pc)as representative for systematic studies,it is found that(1)the ratio WO_(3)(Pc)phase to that of room-temperature phase of WO_(3)(P2_(1)/n)can be tailored by modulation of processing parameters;(2)laser synthesized aerogels with hybrid phases of WO_(3)(Pc)and WO_(3)(P2_(1)/n)have a brighter visible whiteness,higher visible/nearinfrared(NIR)spectral selectivity than the natural prototype of white Cyphochilus insulanus beetles but with comparable LWIR emittance.White WO_(3) aerogel in situ deposited during flexibly fs laser artistic patterning can blur the painting features due to its radiative cooling effect,allowing a colorful impressionistic IR display in the heating mode.What's more,invisible painting features concealed by the white deposited WO_(3) aerogel are clearly/faintly distinguishable by introducing external stimuli of a human hand and sample heating,respectively,catalyzing progress in optical encryption and selectively stimuli-responsive decryption display in the infrared band.展开更多
In this paper, the equilibrium properties of spin-1 Blume–Emery–Griffiths model are studied by using constant-coupling approximation. The dipolar and quadrupolar order parameters, the stable, metastable and unstable...In this paper, the equilibrium properties of spin-1 Blume–Emery–Griffiths model are studied by using constant-coupling approximation. The dipolar and quadrupolar order parameters, the stable, metastable and unstable states and free energy of the model are investigated. The states are defined in terms of local minima of the free energy of system. The numerical calculations are presented for several values of exchange interactions on the simple cubic lattice with q = 6.展开更多
This study investigates the development of novel high-entropy alloys(HEAs)with enhanced mechanical properties through an innovative fabrication method of direct energy deposition(DED).The focus is on the creation of m...This study investigates the development of novel high-entropy alloys(HEAs)with enhanced mechanical properties through an innovative fabrication method of direct energy deposition(DED).The focus is on the creation of metastable core-shell precipitation-strengthened HEAs that exhibit a unique multi-stage terrace-like slip wave toughening mechanism,a novel approach to improving both strength and ductility simultaneously.Mechanical testing reveals that the developed HEAs exhibit superior mechanical proper-ties,including high yield strength,ultimate tensile strength,and exceptional ductility.The improvement in these properties is attributed to the multi-stage terrace-like slip wave toughening mechanism activated by the unique microstructural features.This toughening mechanism involves the sequential activation of slip systems,facilitated by the stress concentration around the core-shell precipitates and the subsequent propagation of slip waves across the material.The terrace-like pattern of these slip waves enhances the material's ability to deform plastically,providing a significant toughening effect while maintaining high strength levels.Furthermore,the study delves into the fundamental interactions between the microstruc-tural elements and the deformation mechanisms.It elucidates how the core-shell precipitates and the matrix cooperate to distribute stress uniformly,delay the onset of necking,and prevent premature failure.This synergistic interaction between the microstructural features and the slip wave toughening mecha-nism is central to the remarkable balance of strength and ductility achieved in the HEAs.The introduction of a multi-stage terrace-like slip wave toughening mechanism offers a new pathway to designing HEAs with an exceptional amalgamation of strength and ductility.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.U2230207)。
文摘Achieving long spin coherence times is crucial for quantum precision measurements,and closed-loop control techniques are often employed to accomplish this goal.Here,we demonstrate the impact of closed-loop feedback control on nuclear spin precession in a metastability exchange optical pumping(MEOP)-based polarized^(3)He system.We analyze the effects of feedback theoretically and validate our predictions experimentally.With optimized feedback parameters,the spin coherence time T_(2)is extended by an order of magnitude.When the feedback strength surpasses a critical threshold,robust maser oscillations are spontaneously excited,demonstrating remarkable resistance to environmental noise and maintaining stable oscillation.This proof-of-principle experiment highlights the viability of MEOP-based^(3)He spin oscillators,especially in low-frequency domains.The operational simplicity and easy integration associated with MEOP-based systems make them particularly promising for fast,high-precision magnetic field measurements.
基金supported by the National Natural Science Foundation of China (Grant Nos.12334001,52461160301,52322311,52427802,12222414)the National Key R&D Program of China (Grant Nos.2024YFA1208201,2021YFA1400500,2021YFA1400204)the Youth Innovation Promotion Association of the CAS (Grant Nos.Y2022003 and 2020009)。
文摘Hafnia-based ferroelectrics have emerged as promising materials for next-generation nanoelectronics owing to their robust nanoscale properties and compatibility with metal-oxide-semiconductor technology.However,their metastable nature remains a key challenge for practical implementation.Utilizing scanning transmission electron microscopy,we investigated the atomic-scale mechanisms governing ferroelectric transitions and the metastability of polar phases in 10-nm-thick Hf_(0.5)Zr_(0.5)O_(2)thin films.Our results demonstrate that oxygen vacancies,coupled with rhombohedral distortions of the cation lattice,facilitate ferroelectric phase transitions and enable robust polar switching through adaptive processes,including cell-by-cell oxygen displacement and domain-wall-mediated nucleation and growth.These findings underscore the pivotal role of oxygen vacancies and lattice distortions in stabilizing polar phases and provide detailed insights into the atomic structures and transition dynamics of polymorphic Hf_(0.5)Zr_(0.5)O_(2-x),thereby advancing its potential for practical device applications.
基金the funds of the National Natural Science Fund for Excellent Young Scholars of China(No.52222410)Shaanxi Province National Science Fund for Distinguished Young Scholars,China(No.2022JC-24)the National Natural Science Foundation of China(Nos.52227807,52034005)。
文摘A fine-grained metastable dual-phase Fe_(40)Mn_(20)Co_(20)Cr_(15)Si_(5)high entropy alloy(CS-HEA)with excellent strength and ductility was successfully prepared by friction stir processing(FSP).The microstructural and mechanical properties of the fine-grained CS-HEA were characterized.The results showed that as-cast shrinkage cavities and elemental segregation were eliminated.The average grain size was refined from 121.1 to 5.4μm.The face-centered cubic phase fraction increased from 23%to 82%.During tensile deformation,dislocation slip dominated at strains ranging from 5%to 17%,followed by transformation induced plasticity(TRIP)from 17%to 26%,and twin induced plasticity(TWIP)from 26%to 37%.The yield strength,ultimate tensile strength,and elongation of the fine-grained CS-HEA were 503 MPa,1120 MPa,and 37%,respectively.The strength-ductility synergy of fine-grained CS-HEA was attributed to the combined effects of TRIP,TWIP,dislocation strengthening,and fine-grained strengthening.
基金supported by the National Natural Science Foundation of China(Grant Nos.52205467 and U21A20138)Youth Science Foundation of Jiangsu Province(Grant No.BK20220531)Science and Technology Planning Project of Zhenjiang-International Scientific and Technological Cooperation(Grant No.GJ2023014)。
文摘Laser powder bed fusion(LPBF)is an attractive additive manufacturing technology for preparing high-performance high-entropy alloys(HEAs)engineering components.Unfortunately,the existence of inherent thermal residual stress and non-equilibrium microstructures in the additively manufactured components results in unsatisfactory mechanical properties.Herein,we propose a novel strengthening strategy,namely deep cryogenic treatment(DCT)followed by laser shock peening(LSP),to tailor the microstructures and enhance performances of an LPBF additively manufactured metastable HEA.The post-treatment effects of DCT+LSP on the LPBF-fabricated Fe_(50)Mn_(30)Co_(10)Cr_(10)HEA are evaluated in terms of microstructural modifications,residual stress,and microhardness redistribution,as well as tensile properties.Results indicate that a gradient heterogeneous structure is formed on the as-built sample surface,featuring gradient variations in grain size,martensitic phase content,and dislocation density,due to the grain refinement and martensitic phase transformation under DCT+LSP.The initial tensile residual stress on the surface is fully transformed into compressive stress,achieving a peak of-289 MPa,and the surface microhardness attains a maximum of 380.8 HV.The various strengthening mechanisms of gradient heterogeneous structures,as well as the multiple effects of heterodeformation-induced(HDI)hardening,transformation-induced plasticity(TRIP),and twinning-induced plasticity(TWIP),are responsible for achieving strength-ductility synergy.This work provides a practical pathway and valuable scientific insights for enhancing the mechanical behaviors of additively manufactured metastable HEAs via microstructural engineering.
基金supported by the National Natural Science Foundation of China,China(Grant No.22305100,No.22405104)the Hubei Provincial International Science and Technology Cooperation Program Project(Grant No.2023EHA014)+4 种基金the National Foreign Experts Program(Grant No.Y20240022,H20240275)the Hubei Natural Science Foundation(Grant No.2025AFB460)the Hubei Provincial Department of Education Scientific Research Project(Grant No.F2023033,Q20234414)the Wuhan Natural Science Foundation Exploration Project(Chenguang Program)(Grant No.2025040601020173)the Jianghan University Scientific Research Startup Fund(Grant No.PBSKL-2022-QD-08,No.PBSKL-2024-QD-03).
文摘As a prototypical high-energy-density reactive material system,metastable intermolecular composites(MICs)have attracted considerable interest owing to their customizable component configurations and interfacial architectures.Nevertheless,their energy release characteristics are fundamentally constrained by the formation of condensed-phase products with elevated boiling points,thereby diminishing their efficacy in applications requiring rapid pressure generation or shock wave propagation.Herein,we demonstrate a molecular-level fluorination approach that enables oxygen substitution by fluorine within bismuth oxide crystalline frameworks,yielding ternary BixOyFz crystals with atomically precise F/O stoichiometric control through systematic solvent polarity engineering.This energetics system,designed through a multilevel regulation strategy,realizes stepwise redox reactions of Al–F and Al–O during energy release,with the partitioning between these redox pathways being precisely allocable through hierarchical regulation.Furthermore,the pre-ignition reaction(PIR)between BixOyFz and Al2O3(the inert passivation shell of Al)weakens the passivation layer,lowering the ignition threshold.The in situ generation of low-boiling-point AlF3 promotes rapid gas expansion,leading to significantly enhanced pressurization rates and deflagration wave velocities under confinement compared to conventional strategies.To evaluate energy output capabilities and validate potential safety-protection applications,the system successfully achieved instantaneous destruction of SD chips,enabling secure data erasure.This work establishes crystalline lattice fluorination as a generalized materials design strategy to transcend intrinsic limitations of MICs systems in component selection and reaction thermodynamics,providing new paradigms for adaptive energetic architectures and transient microelectromechanical applications.
基金financial support received from the Shanghai Pujiang Program(23PJ1406500)。
文摘White Cyphochilus insulanus beetles,exhibiting both environmental camouflage display and radiative cooling functions,serve as a good prototype for biomimetic fabrication.As inspired,this work presents a femtosecond(fs)laser-based biomimetic fabrication strategy that takes full use of the synthesized radiative cooling nanomaterials for a groundbreaking stimuli-responsive infrared(IR)impressionistic camouflage display.The proposed technique is capable of readily transforming various substrates(quartz glass and metals including Ti,Al,Zr,and W)into self-assembled porous networks(aerogels)consisting of oxygen-vacancy-rich oxide nanoparticles.Surprisingly,the emissions of all as-prepared porous particle-networks in the radiative-cooling long-wavelength infrared(LWIR)band are above 95%,with the SiO_(2) aerogels reaching a maximum of 99.6%.Benefiting from the far-from-equilibrium thermodynamic kinetics,metastable phases of anatase TiO_(2),tetragonal zirconia(t-ZrO_(2)),and monoclinic WO_(3)(Pc)are synthesizable,opening up opportunities for exploring their optical applications.Taking the low-temperature metastable phase WO_(3)(Pc)as representative for systematic studies,it is found that(1)the ratio WO_(3)(Pc)phase to that of room-temperature phase of WO_(3)(P2_(1)/n)can be tailored by modulation of processing parameters;(2)laser synthesized aerogels with hybrid phases of WO_(3)(Pc)and WO_(3)(P2_(1)/n)have a brighter visible whiteness,higher visible/nearinfrared(NIR)spectral selectivity than the natural prototype of white Cyphochilus insulanus beetles but with comparable LWIR emittance.White WO_(3) aerogel in situ deposited during flexibly fs laser artistic patterning can blur the painting features due to its radiative cooling effect,allowing a colorful impressionistic IR display in the heating mode.What's more,invisible painting features concealed by the white deposited WO_(3) aerogel are clearly/faintly distinguishable by introducing external stimuli of a human hand and sample heating,respectively,catalyzing progress in optical encryption and selectively stimuli-responsive decryption display in the infrared band.
文摘In this paper, the equilibrium properties of spin-1 Blume–Emery–Griffiths model are studied by using constant-coupling approximation. The dipolar and quadrupolar order parameters, the stable, metastable and unstable states and free energy of the model are investigated. The states are defined in terms of local minima of the free energy of system. The numerical calculations are presented for several values of exchange interactions on the simple cubic lattice with q = 6.
文摘This study investigates the development of novel high-entropy alloys(HEAs)with enhanced mechanical properties through an innovative fabrication method of direct energy deposition(DED).The focus is on the creation of metastable core-shell precipitation-strengthened HEAs that exhibit a unique multi-stage terrace-like slip wave toughening mechanism,a novel approach to improving both strength and ductility simultaneously.Mechanical testing reveals that the developed HEAs exhibit superior mechanical proper-ties,including high yield strength,ultimate tensile strength,and exceptional ductility.The improvement in these properties is attributed to the multi-stage terrace-like slip wave toughening mechanism activated by the unique microstructural features.This toughening mechanism involves the sequential activation of slip systems,facilitated by the stress concentration around the core-shell precipitates and the subsequent propagation of slip waves across the material.The terrace-like pattern of these slip waves enhances the material's ability to deform plastically,providing a significant toughening effect while maintaining high strength levels.Furthermore,the study delves into the fundamental interactions between the microstruc-tural elements and the deformation mechanisms.It elucidates how the core-shell precipitates and the matrix cooperate to distribute stress uniformly,delay the onset of necking,and prevent premature failure.This synergistic interaction between the microstructural features and the slip wave toughening mecha-nism is central to the remarkable balance of strength and ductility achieved in the HEAs.The introduction of a multi-stage terrace-like slip wave toughening mechanism offers a new pathway to designing HEAs with an exceptional amalgamation of strength and ductility.
