The crystallization and aggregation characteristics of the active layer components in organic solar cells(OSCs)are one of the core factors determining photovoltaic performance,influencing the entire process from light...The crystallization and aggregation characteristics of the active layer components in organic solar cells(OSCs)are one of the core factors determining photovoltaic performance,influencing the entire process from light absorption to charge separation,transport,and ultimately charge collection.Dynamic changes in crystallization and aggregation states can also disrupt the microstructure of the active layer,thus shortening the lifetime of the cell.In this study,a morphology modulation strategy is proposed to regulate the crystallization kinetics of non-fullerene acceptors by employing the polymer molecule PYIT as a nucleating agent.An appropriate amount of PYIT was first completely dissolved with the non-fullerene acceptor Y6 and left to stand for 24 h,followed by the fabrication of layer-by-layer processed OSCs.Experiments demonstrated that high crystallinity of PYIT allows it to act as a crystallization nucleus,promoting the crystallization,orientation consistency,and ordered stacking of the acceptor.These nanoscale structural optimizations facilitate efficient charge transport,enhance exciton dissociation efficiency,and suppress unfavorable energetic disorder.Consequently,not only was the power conversion efficiency(PCE)of D18-Cl/Y6-based layer-by-layer processed OSC increased from 18.08%to 19.13%,but the atmospheric stability and long-term lifetime of the OSCs were also significantly improved.Notably,this strategy is also applicable to indoor OSCs,and the PYIT-optimized device can achieve a PCE of 27.0%under 1000 lux light-emitting diode(LED,3200K)irradiation,which is superior to that of the control device(24.2%).This work develops a crystal engineering strategy that is able to simultaneously optimize the microscopic morphology and charge dynamics properties in OSCs,thereby achieving simultaneous improvement in efficiency and stability.展开更多
Inorganic perovskite solar cells(IPSCs),due to their suitable bandgap and superior thermal stability,are ideal candidates for tandem solar cells combined with silicon.However,the development of inorganic perovskite so...Inorganic perovskite solar cells(IPSCs),due to their suitable bandgap and superior thermal stability,are ideal candidates for tandem solar cells combined with silicon.However,the development of inorganic perovskite solar cells has been hindered by suboptimal crystallization dynamics that generate detrimental defects in the perovskite lattice.Here,we propose 4-Methoxyphenylphosphonic Acid(4MPA)as a multifunctional additive to address this challenge.P=O in 4MPA establish strong coordination with undercoordinated Pb^(2+),while-OH engage in O...H-O hydrogen bonding interactions with DMSO,effectively weakening the solvent-[PbX_(6)]^(4-)octahedron interaction.This dual functionality facilitates complete and rapid DMA^(+)-to-Cs^(+)cation exchange while regulating crystallization kinetics,thereby optimizing crystal growth.Furthermore,π-π interactions between benzene rings significantly enhance the moisture resistance of the perovskite layer.The optimized device demonstrates a power conversion efficiency(PCE)of 21.35%,with unencapsulated devices retaining 93,63%of their initial efficiency after 200-hour continuous operation under ambient conditions(35%relative humidity).展开更多
Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening ...Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.展开更多
Mg_(x)(Ni_(0.8)La_(0.2))_(100-x),where x=60,70,80,exhibiting a nanocrystalline microstructure,were prepared through the crystallization of amorphous alloys.The investigation encompassed the phase constitution,grain si...Mg_(x)(Ni_(0.8)La_(0.2))_(100-x),where x=60,70,80,exhibiting a nanocrystalline microstructure,were prepared through the crystallization of amorphous alloys.The investigation encompassed the phase constitution,grain size,microstructural stability,and hydrogen storage properties.Crystallization kinetics,along with in-situ high-energy XRD characterization,revealed a concentrated and synchronous crystallization of Mg_(2)Ni and RE-Mg-Ni ternary phases with the increase in La and Ni content.The attributed synchronous crystallization process was found to be a result of the close local affinity of Mg_(2)Ni and RE-Mg-Ni ternary phases,as assessed by the thermodynamic Miedema model.Significant secondary phase pinning effect,arising from the high likelihood of well-matching phase structures between Mg_(2)Ni,LaMg_(2)Ni,and LaMgNi_(4),was validated through both the edge-to-edge matching model prediction and experimental observation.Thefine and homogeneous microstructure was shown to be a consequence of fast crystallization kinetics and the secondary phase pinning effect.Improved activation performance and cycling stability were observed,stemming from grain refinement and excellent microstructural stability.Our study provides insights into mechanism of grain refinement of nanocrystalline microstructure tailored by phase constitution and crystallization kinetics in the amorphous-crystallization route.We also demonstrate the potential of material design guided by phase equilibria and crystallographic predictions to improve nanocrystalline with excellent microstructural stability.展开更多
A trinuclear copper complex [Cu_(3)(L2)_(2)(SO_(4))_(2)(H_(2)O)_(7)]·8H_(2)O(1)(HL2=1-hydroxy-3-(pyrazin-2-yl)-N-(pyrazin-2-ylmethyl)imidazo[1,5-a]pyrazine-8-carboxamide) with a multi-substituted imidazo[1,5-a]py...A trinuclear copper complex [Cu_(3)(L2)_(2)(SO_(4))_(2)(H_(2)O)_(7)]·8H_(2)O(1)(HL2=1-hydroxy-3-(pyrazin-2-yl)-N-(pyrazin-2-ylmethyl)imidazo[1,5-a]pyrazine-8-carboxamide) with a multi-substituted imidazo[1,5-a]pyrazine scaffold was serendipitously prepared from the reaction of the pro-ligand of H_(2)L1(N,N'-bis(pyrazin-2-ylmethyl)pyrazine-2,3-dicarboxamide) with CuSO_(4)·5H_(2O) in aqueous solution at room temperature.Complex 1 was characterized by IR,single-crystal X-ray analysis,and magnetic susceptibility measurements.Single-crystal X-ray analysis reveals that the complex consists of three Cu(Ⅱ) ions,two in situ transformed L2~-ligands,two coordinated sulfates,seven coordinated water molecules,and eight uncoordinated water molecules.Magnetic susceptibility measurement indicates that there are obvious ferromagnetic coupling interactions between the adjacent Cu(Ⅱ) ions in 1.CCDC:1852713.展开更多
Perovskite single crystals(PSCs)have attracted significant interest for next-generation radiation detection.However,the lack of in-depth crystal growth kinetics of PSCs limits the development of high-quality PSCs.Here...Perovskite single crystals(PSCs)have attracted significant interest for next-generation radiation detection.However,the lack of in-depth crystal growth kinetics of PSCs limits the development of high-quality PSCs.Here,with an in-situ real-time monitoring system for MAPbBr3 PSCs growth during the antisolvent vapor-assisted crystallization(AVC)process,the growth curves of MAPbBr3 PSCs are obtained and the growth kinetics are theoretically modeled.Two important factors,including antisolvent vapor flux and initial precursor concentration,have been investigated experimentally for their impacts on crystal quality.By controlling the antisolvent vapor flux,the nucleation of PSCs at the container-solution interface can be regulated;while by controlling the initial precursor concentration,the crystal quality can be improved.The optimized MAPbBr3 PSCs exhibited significantly high qualities,with the narrowest reported full width at half maximum(0.00637°)of X-ray diffraction rocking curve as reported,a trap-state density as low as 2.12×10^(10 )cm^(−3),and a mobility-lifetime(μτ)product of 1.4×10^(−2) cm^(2) V^(−1).The fabricated X-ray detectors demonstrated optimal performance at an electric field of 20 V/mm,with a sensitivity of 9.02×10^(3)μC Gy^(−1) cm^(−2) and the lowest detectable dose rate of 0.08μGy s^(−1) under irradiation with continuum X-ray energy up to 20 keV.This work provides valuable insights for the development of high-quality PSCs for direct radiation detection.展开更多
We performed the coupled molecular-dynamics and spin dynamics simulations to investigate the magnetic annealing effect on the crystallization behavior of Fe metallic glasses(MGs). By calculating the local five-fold sy...We performed the coupled molecular-dynamics and spin dynamics simulations to investigate the magnetic annealing effect on the crystallization behavior of Fe metallic glasses(MGs). By calculating the local five-fold symmetry, Voronoi polyhedron, and bond orientational order parameters, we find a significant structural evolution at high-frequency magnetic annealing: the icosahedral order diminishes, and the crystalline-like order is enhanced, comparing to the case without magnetic field. The fraction of the body-centered cubic structures remarkably increases with the frequency of magnetic annealing, and the atoms of these order show a tendency of aggregating in space to form the crystalline nuclei. These findings unveil how the local structure evolves under magnetic annealing, and the accelerated crystallization process of MGs through alternating magnetic fields.展开更多
Additive engineering has been widely employed to address defects-related issues in perovskite solar cells,including Pb^(2+)vacancy defects,halide migration,and FA^(+)lattice mismatch.However,due to the diversity and c...Additive engineering has been widely employed to address defects-related issues in perovskite solar cells,including Pb^(2+)vacancy defects,halide migration,and FA^(+)lattice mismatch.However,due to the diversity and complexity of defect types in perovskites,traditional monofunctional additives are typically limited to passivate specific types of defects and are unable to achieve effective passivation of multiple defects simultaneously.To overcome this limitation,this work proposes a multidentate synergistic coordination strategy using a multifunctional additive,ethyl 4-aminopyrazole-5-carboxylate(EAPC),to achieve coordinated passivation of multiple defects in perovskites.Combined theoretical calculations and experimental investigations reveal that the carbonyl group(C=O)of EAPC forms strong coordination bonds with uncoordinated Pb^(2+),while its amino group(–NH_(2))couples with halide ions,and the pyrazole-ring N sites establish a hydrogen-bonding network with FA^(+)cations,thereby achieving triple-site synergistic passivation of Pb^(2+)-X^(-)-FA^(+)defects.This synergistic effect accelerates the nucleation kinetics of perovskite while retarding its growth rate,thereby reducing the defect density and enhancing the crystallinity of the resulting perovskite films.Based on this strategy,the inverted perovskite solar cells(PSCs)achieved a champion power conversion efficiency(PCE)of 24.40%,maintaining over 90.2%of their initial efficiency after 1000 h of aging in a N_(2)-glovebox environment and retaining 85.1%of the original PCE under ambient conditions.This work pioneers a novel paradigm for synergistic defect passivation in perovskite optoelectronic devices.展开更多
Terahertz(THz)switches are essential components of THz communication systems.THz switches based on conventional waveguides and photonic crystal structures are sensitive to manufacturing defects and sharp bending,resul...Terahertz(THz)switches are essential components of THz communication systems.THz switches based on conventional waveguides and photonic crystal structures are sensitive to manufacturing defects and sharp bending,resulting in high scattering losses.In addition,THz switches with tunable working bandwidths have not yet been demonstrated.Here,we design THz switches based on a topological valley photonic crystal(VPC)structure using magnetic materials,which can achieve high forward transmittance based on the unique spin–valley locking effect.The broad working bandwidth allows selective turning on and off at a designed wavelength region by controlling the applied magnetic field.The designed THz switch can achieve an extinction ratio of up to 31.66 dB with an insertion loss of less than 0.13 dB.The 3-dB bandwidth is up to 49 GHz.This tunable THz switch can be experimentally fabricated by current fabrication techniques and thus can find broad applications in THz communication systems.展开更多
The effects of synthesis conditions,especially the heating rate,on the reaction kinetics of Ni-rich cathodes were systematically studied.The growth rate of Ni-rich oxide increases continuously as the heating rate incr...The effects of synthesis conditions,especially the heating rate,on the reaction kinetics of Ni-rich cathodes were systematically studied.The growth rate of Ni-rich oxide increases continuously as the heating rate increases.Ab initio molecular dynamics simulations demonstrate that a high heating rate induces anabatic oscillations,indicating a decrease in thermodynamic stability and a tendency for the crystal surface to undergo reconstruction.The presence of an intermediate phase at the grain boundary amplifies atomic migration-induced interface fusion and consequently augments crystal growth kinetics.However,the excessively high heating rate aggravates the Li+/Ni2+mixing in the Ni-rich cathode.The single-crystal Ni-rich cathode exhibits enhanced structural/thermal stability but a decreased specific capacity and rate performance compared with its polycrystalline counterpart.展开更多
We report the magnetic and transport properties of EuBi_(2) single crystal. EuBi_(2) exhibits complex magnetic behavior at low temperatures. In both the in-plane and out-of-plane directions, three antiferromagnetic(AF...We report the magnetic and transport properties of EuBi_(2) single crystal. EuBi_(2) exhibits complex magnetic behavior at low temperatures. In both the in-plane and out-of-plane directions, three antiferromagnetic(AFM) transitions have been observed at T_(N1)~18.9 K, T_(N2)~7.0 K, and T_(N3)~3.1 K. Among them, the transitions at T_(N2) and T_(N3) represent the canted AFM orders with ferromagnetic components. As the magnetic field increases, the transition at T_(N3) is rapidly suppressed to disappearance. However, the transitions at T_(N1) and T_(N2) persist until high fields and their signatures can also be reflected in the resistivity and specific heat. Above the magnetic transition temperature T_(N1), the resistivity of EuBi_(2) increases linearly with temperature, exhibiting the strange-metal behavior. In the magnetically ordered region below T_(N1), EuBi_(2) exhibits the weak antilocalization(WAL) effect and large magnetoresistance(475% at 1.8 K and 14 T). It is suggested that the magnetic ordering significantly enhances the spin–orbital coupling interaction and induces the WAL effect.展开更多
To elucidate the deformation mechanisms ofγ-TiAl,the nanoindentation experiments and crystal plasticity finite element(CPFE)simulation were employed to investigate the effects of crystal orientations and GBs on the m...To elucidate the deformation mechanisms ofγ-TiAl,the nanoindentation experiments and crystal plasticity finite element(CPFE)simulation were employed to investigate the effects of crystal orientations and GBs on the mechanical properties ofγ-TiAl alloys.A crystal plasticity constitutive model was developed,and load-displacement curves,hardness,and Young's modulus were obtained for both single grains and GBs inγ-TiAl alloys.Based on the aforementioned model,this study investigated the distribution patterns of surface morphology around the indentation sites of individual grain and GBs.It also analyzed the cumulative shear strain distribution,slip system activation,and the interaction between GBs and dislocation slip for various crystal orientations.The results indicate that the mechanical response and pileup behavior exhibit significant anisotropy due to the interplay among the indenter geometry,material slip systems,and cumulative shear strain distribution.Moreover,the interaction between GBs and dislocation slip substantially alters dislocation distribution,thereby influencing material flow and playing a critical role in the mechanical response and plastic deformation of the material.展开更多
BACKGROUND Acute hemorrhagic leukoencephalitis(AHLE),also known as Weston-Hurst syndrome,is a very rare and fulminant form of demyelinating disorder.It is considered a hyperacute and severe variant of acute disseminat...BACKGROUND Acute hemorrhagic leukoencephalitis(AHLE),also known as Weston-Hurst syndrome,is a very rare and fulminant form of demyelinating disorder.It is considered a hyperacute and severe variant of acute disseminated encephalomyelitis.Clinically,patients present with fever,headache,seizures,and altered sensorium,which can rapidly progress to coma or death.Magnetic resonance imaging(MRI)is the investigation of choice and plays a pivotal role in diagnosing AHLE.The purpose of this article is to make readers familiar with the typical MRI features of AHLE and to discuss differentials.CASE SUMMARY This case series reports the clinical presentation and typical neuroimaging findings in four patients diagnosed with AHLE.All patients presented with acute neurological symptoms,such as severe headaches,seizures,and altered consciousness,often following a history of fever suggesting an infectious etiology.Additionally,laboratory investigations demonstrated elevated levels of serum inflammatory markers and neutrophilic pleocytosis on cerebrospinal fluid analysis,supporting a post-infectious etiology.MRI findings consistently revealed characteristic white matter lesions with hemorrhagic foci and vasogenic edema,indicative of widespread demyelination characteristic of AHLE.The outcomes varied,with two patients surviving but experiencing neurological sequelae,while two others unfortunately succumbed to the disease.The clinical data,laboratory results,and imaging findings from this case series were systematically compared with those from previously published studies.The key similarities and differences in clinical presentation,imaging characteristics,and outcomes are presented in a tabulated format.CONCLUSION AHLE is associated with high morbidity and mortality rates,emphasizing the need for early recognition,prompt intervention,and multidisciplinary management.Further research is needed to explain the pathophysiological mechanisms underlying AHLE,identify potential biomarkers for early diagnosis,and develop targeted therapies to improve patient outcomes.展开更多
Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'...Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.展开更多
Using multi-directional forging temperature as the independent variable and adopting the dual-mode phase field crystal model,the nucleation modes,reaction mechanisms,and interactions between grain boundaries and dislo...Using multi-directional forging temperature as the independent variable and adopting the dual-mode phase field crystal model,the nucleation modes,reaction mechanisms,and interactions between grain boundaries and dislocations at different temperatures were investigated.Results show that a mapping relationship between process parameters and grain refinement/coarsening is established,and the optimal processing temperature coefficient is 0.23.Compared with the cases with processing temperature coefficient of 0.19,0.20,0.21,0.25,and 0.27,the refinement effect increases by 256.0%,146.0%,113.0%,6.7%,and 52.4%,respectively.Excessively high temperatures lead to grain coarsening due to dislocation annihilation,and the application of strain can reduce the actual melting point of materials.Even if the processing temperature does not exceed the theoretical melting point,remelting and crystallization may still occur,resulting in an overburning phenomenon that reduces internal defects and increases overall grain size.This research is of great significance for the actual forging process design.展开更多
In this work,five kinds of crystals were successfully synthesized using the Czochralski method for the first time,namely Dy∶Ca_(3)Li_(0.275)Nb_(1.775)Ga_(2.95)O_(12)(CLNGG),Dy,Tb∶CLNGG,Dy,Eu∶CLNGG,Tb∶CLNGG,and Eu...In this work,five kinds of crystals were successfully synthesized using the Czochralski method for the first time,namely Dy∶Ca_(3)Li_(0.275)Nb_(1.775)Ga_(2.95)O_(12)(CLNGG),Dy,Tb∶CLNGG,Dy,Eu∶CLNGG,Tb∶CLNGG,and Eu∶CLNGG.A detailed investigation of spectral features and energy transfer mechanisms in such crystals was conducted by analyzing their optical absorption spectra,excitation and emission spectra,and fluorescence decay curves at ambient tem-perature.Calculations based on the Judd-Ofelt theory further elucidated these features.The results demonstrate that in the Dy^(3+)system,co-doping with Tb^(3+)and Eu^(3+)ions not only enhances the emission cross-sections in the yellow wavelength re-gion but also improves the fluorescence quantum efficiency.These improvements are particularly beneficial for achieving efficient yellow light output from Dy^(3+).Additionally,the studies confirm the occurrence of reciprocal energy transfer be-tween Dy^(3+)and Tb^(3+)ions in Dy,Tb∶CLNGG crystals,whereas unidirectional energy transfer from Dy^(3+)to Eu^(3+)occurs in Dy,Eu∶CLNGG crystals.Based on the obtained research results,Dy,Tb∶CLNGG and Dy,Eu∶CLNGG crystals could be utilized as compelling and potential laser media for diode-pumped all-solid-state yellow lasers.展开更多
The exploration and synthesis of new materials are important for materials science and condensed matter physics.Here, we report the crystal structure, magnetic properties, and electrical transport properties of the si...The exploration and synthesis of new materials are important for materials science and condensed matter physics.Here, we report the crystal structure, magnetic properties, and electrical transport properties of the single crystals of Nd_(5)ScSb_(12), which is a quasi-one-dimensional new compound. Nd_(5)ScSb_(12) exhibits antiferromagnetic transition in both directions perpendicular and parallel to the long axis. Moreover, the magnetic field-dependent magnetization reveals two metamagnetic transitions. The electrical transport properties have been measured on the same sample but with different measurement lengths between the electrodes of the voltage. The resistivity exhibits the metallic behavior. At low temperatures, the Kondo effect and negative transverse magnetoresistance(MR)(B⊥I) have been observed. Interestingly, the measurement length has a significant impact on the Kondo effect and negative MR, providing an intuitive new approach to regulate the Kondo effect. As the measurement length increases, the Kondo effect and negative MR become more pronounced. This not only indicates that the interaction between magnetic impurities and conduction electrons dominates the electrical transport of Nd_(5)ScSb_(12) at low temperatures, but also confirms that the negative MR originates from the suppression of the Kondo effect.展开更多
Poly(_(L)-lactide)(PLLA),a leading biodegradable polyester,has demonstrated potential as a sustainable alternative,owing to its excellent biodegradability and rigidity.However,their slow crystallization kinetics and p...Poly(_(L)-lactide)(PLLA),a leading biodegradable polyester,has demonstrated potential as a sustainable alternative,owing to its excellent biodegradability and rigidity.However,their slow crystallization kinetics and poor heat resistance limit their application scope.Recent advances have highlighted that the combination of extensional flow and thermal fields can achieve toughness–stiffness balance,high transparency,and good heat resistance.However,the effect of extensional flow on the post-non-isothermal crystallization of PLLA during heating and the resulting crystalline texture remains unclear.In this study,PLLA with a heterogeneous amorphous structure and oriented polymorph was prepared by extensional flow.The effect of heterogeneous amorphous structures on non-isothermal crystallization kinetics during the heating process was studied by thermal analysis,polarized optical microscopy,infrared spectroscopy,and ex situ/in situ X-ray characterization.These results clearly illustrate that extensional flow enhances the formation of oriented crystalline structures,accelerates non-isothermal crystallization,and modulates the polymorphic composition of PLLA.Moreover,an unexpected dual cold-crystallization behavior is identified in ordered PLLA samples upon extensional flow,which is from the extensional flow-induced heterogeneous amorphous phase into α' phase(low-temperature peak)and the pristine amorphous phase intoαphase(high-temperature peak).The extensional flow primarily promotes the formation of the more perfectαandα'phases,but has a negative effect on the final content ofαphase formed after cold crystallization andα'-to-αphase transformation.The findings of this work advance the understanding of PLLA non-isothermal crystallization after extensional flow and offer valuable guidance for high-performance PLLA upon heat treatment in practical processing.展开更多
Energetic materials face critical challenges in balancing energy density and safety,driving the development of low-sensitivity high-energy materials.Though vital for modern defense and civilian applications,low-sensit...Energetic materials face critical challenges in balancing energy density and safety,driving the development of low-sensitivity high-energy materials.Though vital for modern defense and civilian applications,low-sensitivity high-energy materials remain scarce,with 1,3,5-trinitro-2,4,6-triaminobenzene as the only deployed example.Planar lamellar energetic crystals,which utilize weak interlamellarπ-πstacking for mechanical energy dissipation,have shown significant promise.However,their rational design is constrained by insufficient understanding of intermolecular interaction synergy.This review synthesizes the structural features of planar lamellar energetic crystals,emphasizing three core elements:the single-atomic-thickness planar stacking architecture,the"strong intralamellar and weak interlamellar interaction"paradigm(key to balancing energy density and safety for low-sensitivity high-energy materials,LSHEMs),and the role of molecular planarity in reducing shear slip barriers.It categorizes design strategies into two frameworks:H–bonding dominated(single-component:cross-shaped assembly,strong H–bonding in high symmetric molecules;multi-component methods:tenon-and-mortise,acceptor-donor separation)and other intermolecular interactions(e.g.,π-πstacking-drivenπ-π2max model,π-hole recognition).Case studies in single/multi-component crystals confirm that these strategies tune interaction synergy to achieve target packing motifs.The review highlights that interaction engineering is pivotal for PLEC design,offering a targeted theoretical framework for rational development of LSHEMs(to address the scarcity of practical LSHEMs)and guiding future crystal engineering for energy-safety balanced systems.展开更多
基金supported by the National Natural Science Foundation of China (NSFC grant no. 62474028, 52130304, and62222503)the Natural Science Foundation of Sichuan Province(2025ZNSFSC0037, 2025ZNSFSC1460, and 2024NSFSC1447)+1 种基金the National Key R and D Program of China (2023YFB2604101)sponsored by the Sichuan Province Key Laboratory of Display Science and Technology
文摘The crystallization and aggregation characteristics of the active layer components in organic solar cells(OSCs)are one of the core factors determining photovoltaic performance,influencing the entire process from light absorption to charge separation,transport,and ultimately charge collection.Dynamic changes in crystallization and aggregation states can also disrupt the microstructure of the active layer,thus shortening the lifetime of the cell.In this study,a morphology modulation strategy is proposed to regulate the crystallization kinetics of non-fullerene acceptors by employing the polymer molecule PYIT as a nucleating agent.An appropriate amount of PYIT was first completely dissolved with the non-fullerene acceptor Y6 and left to stand for 24 h,followed by the fabrication of layer-by-layer processed OSCs.Experiments demonstrated that high crystallinity of PYIT allows it to act as a crystallization nucleus,promoting the crystallization,orientation consistency,and ordered stacking of the acceptor.These nanoscale structural optimizations facilitate efficient charge transport,enhance exciton dissociation efficiency,and suppress unfavorable energetic disorder.Consequently,not only was the power conversion efficiency(PCE)of D18-Cl/Y6-based layer-by-layer processed OSC increased from 18.08%to 19.13%,but the atmospheric stability and long-term lifetime of the OSCs were also significantly improved.Notably,this strategy is also applicable to indoor OSCs,and the PYIT-optimized device can achieve a PCE of 27.0%under 1000 lux light-emitting diode(LED,3200K)irradiation,which is superior to that of the control device(24.2%).This work develops a crystal engineering strategy that is able to simultaneously optimize the microscopic morphology and charge dynamics properties in OSCs,thereby achieving simultaneous improvement in efficiency and stability.
基金the financial support from the Yunnan Provincial Science and Technology Project at Southwest United Graduate School(Grant No.202302A0370009)the National Natural Science Foundation Joint Fund(Grant No.U21A2072)+4 种基金the National Science Foundation(Grant No.62274099)the Key Project of Tianjin Natural Science Foundation(Grant No.24JCZDJC01360)the China Higher Education Discipline Innovation Overseas Expert Introduction Project(Grant No.B16027)Tianjin Science and Technology Project(Grant No.24ZXZSSS00160)the Special Fund for Basic Scientific Research of the Central Universities。
文摘Inorganic perovskite solar cells(IPSCs),due to their suitable bandgap and superior thermal stability,are ideal candidates for tandem solar cells combined with silicon.However,the development of inorganic perovskite solar cells has been hindered by suboptimal crystallization dynamics that generate detrimental defects in the perovskite lattice.Here,we propose 4-Methoxyphenylphosphonic Acid(4MPA)as a multifunctional additive to address this challenge.P=O in 4MPA establish strong coordination with undercoordinated Pb^(2+),while-OH engage in O...H-O hydrogen bonding interactions with DMSO,effectively weakening the solvent-[PbX_(6)]^(4-)octahedron interaction.This dual functionality facilitates complete and rapid DMA^(+)-to-Cs^(+)cation exchange while regulating crystallization kinetics,thereby optimizing crystal growth.Furthermore,π-π interactions between benzene rings significantly enhance the moisture resistance of the perovskite layer.The optimized device demonstrates a power conversion efficiency(PCE)of 21.35%,with unencapsulated devices retaining 93,63%of their initial efficiency after 200-hour continuous operation under ambient conditions(35%relative humidity).
基金supported by the National Natural Science Foundation of China(Nos.52071053,U1704253,and 52103334).
文摘Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.
基金supported by National Natural Science Foundation of China(51761034,51961032,51962028 and 52261041)Innovation Foundation of Inner Mongolia University of Science and Technology(2019YQL03)+2 种基金Major Science and Technology Project of Inner Mongolia(2021ZD0029)Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(NJYT23005,NJYT23007)Program for Innovative Research Team in Universities of Inner Mongolia Autonomous Region(NMGIRT2401).
文摘Mg_(x)(Ni_(0.8)La_(0.2))_(100-x),where x=60,70,80,exhibiting a nanocrystalline microstructure,were prepared through the crystallization of amorphous alloys.The investigation encompassed the phase constitution,grain size,microstructural stability,and hydrogen storage properties.Crystallization kinetics,along with in-situ high-energy XRD characterization,revealed a concentrated and synchronous crystallization of Mg_(2)Ni and RE-Mg-Ni ternary phases with the increase in La and Ni content.The attributed synchronous crystallization process was found to be a result of the close local affinity of Mg_(2)Ni and RE-Mg-Ni ternary phases,as assessed by the thermodynamic Miedema model.Significant secondary phase pinning effect,arising from the high likelihood of well-matching phase structures between Mg_(2)Ni,LaMg_(2)Ni,and LaMgNi_(4),was validated through both the edge-to-edge matching model prediction and experimental observation.Thefine and homogeneous microstructure was shown to be a consequence of fast crystallization kinetics and the secondary phase pinning effect.Improved activation performance and cycling stability were observed,stemming from grain refinement and excellent microstructural stability.Our study provides insights into mechanism of grain refinement of nanocrystalline microstructure tailored by phase constitution and crystallization kinetics in the amorphous-crystallization route.We also demonstrate the potential of material design guided by phase equilibria and crystallographic predictions to improve nanocrystalline with excellent microstructural stability.
文摘A trinuclear copper complex [Cu_(3)(L2)_(2)(SO_(4))_(2)(H_(2)O)_(7)]·8H_(2)O(1)(HL2=1-hydroxy-3-(pyrazin-2-yl)-N-(pyrazin-2-ylmethyl)imidazo[1,5-a]pyrazine-8-carboxamide) with a multi-substituted imidazo[1,5-a]pyrazine scaffold was serendipitously prepared from the reaction of the pro-ligand of H_(2)L1(N,N'-bis(pyrazin-2-ylmethyl)pyrazine-2,3-dicarboxamide) with CuSO_(4)·5H_(2O) in aqueous solution at room temperature.Complex 1 was characterized by IR,single-crystal X-ray analysis,and magnetic susceptibility measurements.Single-crystal X-ray analysis reveals that the complex consists of three Cu(Ⅱ) ions,two in situ transformed L2~-ligands,two coordinated sulfates,seven coordinated water molecules,and eight uncoordinated water molecules.Magnetic susceptibility measurement indicates that there are obvious ferromagnetic coupling interactions between the adjacent Cu(Ⅱ) ions in 1.CCDC:1852713.
基金supported by the National Key Research and Development Program of China(No.2020YFB2206103)the Na-tional Natural Science Foundation(Nos.61975196,62274160,and 62250010)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB43020100)the Youth Innova-tion Promotion Association of the Chinese Academy of Sciences(2021111).
文摘Perovskite single crystals(PSCs)have attracted significant interest for next-generation radiation detection.However,the lack of in-depth crystal growth kinetics of PSCs limits the development of high-quality PSCs.Here,with an in-situ real-time monitoring system for MAPbBr3 PSCs growth during the antisolvent vapor-assisted crystallization(AVC)process,the growth curves of MAPbBr3 PSCs are obtained and the growth kinetics are theoretically modeled.Two important factors,including antisolvent vapor flux and initial precursor concentration,have been investigated experimentally for their impacts on crystal quality.By controlling the antisolvent vapor flux,the nucleation of PSCs at the container-solution interface can be regulated;while by controlling the initial precursor concentration,the crystal quality can be improved.The optimized MAPbBr3 PSCs exhibited significantly high qualities,with the narrowest reported full width at half maximum(0.00637°)of X-ray diffraction rocking curve as reported,a trap-state density as low as 2.12×10^(10 )cm^(−3),and a mobility-lifetime(μτ)product of 1.4×10^(−2) cm^(2) V^(−1).The fabricated X-ray detectors demonstrated optimal performance at an electric field of 20 V/mm,with a sensitivity of 9.02×10^(3)μC Gy^(−1) cm^(−2) and the lowest detectable dose rate of 0.08μGy s^(−1) under irradiation with continuum X-ray energy up to 20 keV.This work provides valuable insights for the development of high-quality PSCs for direct radiation detection.
基金Project supported by the Scientific Research Foundation of the Education Department of Hunan Province,China (Grant No. 24A0007)the National Natural Science Foundation of China (Grant No. 52371168)the Foundation of Science and Technology on Surface Physics and Chemistry Laboratory(Grant No. JCKYS2024120202)。
文摘We performed the coupled molecular-dynamics and spin dynamics simulations to investigate the magnetic annealing effect on the crystallization behavior of Fe metallic glasses(MGs). By calculating the local five-fold symmetry, Voronoi polyhedron, and bond orientational order parameters, we find a significant structural evolution at high-frequency magnetic annealing: the icosahedral order diminishes, and the crystalline-like order is enhanced, comparing to the case without magnetic field. The fraction of the body-centered cubic structures remarkably increases with the frequency of magnetic annealing, and the atoms of these order show a tendency of aggregating in space to form the crystalline nuclei. These findings unveil how the local structure evolves under magnetic annealing, and the accelerated crystallization process of MGs through alternating magnetic fields.
基金financially supported by the Changzhou Shichuang Energy Co.Ltd of China(Grant no.K81B2038)the National Natural Science Foundation of China(Grant no.50902116)。
文摘Additive engineering has been widely employed to address defects-related issues in perovskite solar cells,including Pb^(2+)vacancy defects,halide migration,and FA^(+)lattice mismatch.However,due to the diversity and complexity of defect types in perovskites,traditional monofunctional additives are typically limited to passivate specific types of defects and are unable to achieve effective passivation of multiple defects simultaneously.To overcome this limitation,this work proposes a multidentate synergistic coordination strategy using a multifunctional additive,ethyl 4-aminopyrazole-5-carboxylate(EAPC),to achieve coordinated passivation of multiple defects in perovskites.Combined theoretical calculations and experimental investigations reveal that the carbonyl group(C=O)of EAPC forms strong coordination bonds with uncoordinated Pb^(2+),while its amino group(–NH_(2))couples with halide ions,and the pyrazole-ring N sites establish a hydrogen-bonding network with FA^(+)cations,thereby achieving triple-site synergistic passivation of Pb^(2+)-X^(-)-FA^(+)defects.This synergistic effect accelerates the nucleation kinetics of perovskite while retarding its growth rate,thereby reducing the defect density and enhancing the crystallinity of the resulting perovskite films.Based on this strategy,the inverted perovskite solar cells(PSCs)achieved a champion power conversion efficiency(PCE)of 24.40%,maintaining over 90.2%of their initial efficiency after 1000 h of aging in a N_(2)-glovebox environment and retaining 85.1%of the original PCE under ambient conditions.This work pioneers a novel paradigm for synergistic defect passivation in perovskite optoelectronic devices.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1404201)Australia Research Council(Grant Nos.DP220100603 and FT220100559)+7 种基金the National Natural Science Foundation of China(Grant No.U23A20375)the Natural Science Foundation of Shanxi Province(Grant No.202403021211011)Research Project Supported by Shanxi Scholarship Council of China(Grant No.2024-032)Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(Grant No.20240006)the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices(Grant No.KF202402)Basic Scientific Research Conditions and Major Scientific Instrument and Equipment Development of Anhui Science and Technology Department(Grant No.2023YFF0715700)Key Research Project of Shanxi Province(Grant No.202302150101001)Linkage Project Scheme(Grant Nos.LP210200345 and LP210100467).
文摘Terahertz(THz)switches are essential components of THz communication systems.THz switches based on conventional waveguides and photonic crystal structures are sensitive to manufacturing defects and sharp bending,resulting in high scattering losses.In addition,THz switches with tunable working bandwidths have not yet been demonstrated.Here,we design THz switches based on a topological valley photonic crystal(VPC)structure using magnetic materials,which can achieve high forward transmittance based on the unique spin–valley locking effect.The broad working bandwidth allows selective turning on and off at a designed wavelength region by controlling the applied magnetic field.The designed THz switch can achieve an extinction ratio of up to 31.66 dB with an insertion loss of less than 0.13 dB.The 3-dB bandwidth is up to 49 GHz.This tunable THz switch can be experimentally fabricated by current fabrication techniques and thus can find broad applications in THz communication systems.
基金funded by the National Natural Science Foundation of China(No.22379052)Taishan Scholars of Shandong Province,China(No.tsqnz20221143)。
文摘The effects of synthesis conditions,especially the heating rate,on the reaction kinetics of Ni-rich cathodes were systematically studied.The growth rate of Ni-rich oxide increases continuously as the heating rate increases.Ab initio molecular dynamics simulations demonstrate that a high heating rate induces anabatic oscillations,indicating a decrease in thermodynamic stability and a tendency for the crystal surface to undergo reconstruction.The presence of an intermediate phase at the grain boundary amplifies atomic migration-induced interface fusion and consequently augments crystal growth kinetics.However,the excessively high heating rate aggravates the Li+/Ni2+mixing in the Ni-rich cathode.The single-crystal Ni-rich cathode exhibits enhanced structural/thermal stability but a decreased specific capacity and rate performance compared with its polycrystalline counterpart.
基金Project supported by the National Key Research and Development Program of China (Grant No. 2023YFA1406500)the National Natural Science Foundation of China (Grant Nos. 12474098, 12274388, 12174361, 12404191, 52102333, 12404043, and 12204004)the Natural Science Foundation of Anhui Province (Grant No. 2408085QA024)。
文摘We report the magnetic and transport properties of EuBi_(2) single crystal. EuBi_(2) exhibits complex magnetic behavior at low temperatures. In both the in-plane and out-of-plane directions, three antiferromagnetic(AFM) transitions have been observed at T_(N1)~18.9 K, T_(N2)~7.0 K, and T_(N3)~3.1 K. Among them, the transitions at T_(N2) and T_(N3) represent the canted AFM orders with ferromagnetic components. As the magnetic field increases, the transition at T_(N3) is rapidly suppressed to disappearance. However, the transitions at T_(N1) and T_(N2) persist until high fields and their signatures can also be reflected in the resistivity and specific heat. Above the magnetic transition temperature T_(N1), the resistivity of EuBi_(2) increases linearly with temperature, exhibiting the strange-metal behavior. In the magnetically ordered region below T_(N1), EuBi_(2) exhibits the weak antilocalization(WAL) effect and large magnetoresistance(475% at 1.8 K and 14 T). It is suggested that the magnetic ordering significantly enhances the spin–orbital coupling interaction and induces the WAL effect.
基金National Natural Science Foundation of China(52065036,52365018)Natural Science Foundation of Gansu(23JRRA760,24JRRA175,25JRRA060)+1 种基金Hongliu Outstanding Youth Foundation of Lanzhou University of TechnologyLeading Innovative Talents Project of Changzhou(CQ20210111)。
文摘To elucidate the deformation mechanisms ofγ-TiAl,the nanoindentation experiments and crystal plasticity finite element(CPFE)simulation were employed to investigate the effects of crystal orientations and GBs on the mechanical properties ofγ-TiAl alloys.A crystal plasticity constitutive model was developed,and load-displacement curves,hardness,and Young's modulus were obtained for both single grains and GBs inγ-TiAl alloys.Based on the aforementioned model,this study investigated the distribution patterns of surface morphology around the indentation sites of individual grain and GBs.It also analyzed the cumulative shear strain distribution,slip system activation,and the interaction between GBs and dislocation slip for various crystal orientations.The results indicate that the mechanical response and pileup behavior exhibit significant anisotropy due to the interplay among the indenter geometry,material slip systems,and cumulative shear strain distribution.Moreover,the interaction between GBs and dislocation slip substantially alters dislocation distribution,thereby influencing material flow and playing a critical role in the mechanical response and plastic deformation of the material.
文摘BACKGROUND Acute hemorrhagic leukoencephalitis(AHLE),also known as Weston-Hurst syndrome,is a very rare and fulminant form of demyelinating disorder.It is considered a hyperacute and severe variant of acute disseminated encephalomyelitis.Clinically,patients present with fever,headache,seizures,and altered sensorium,which can rapidly progress to coma or death.Magnetic resonance imaging(MRI)is the investigation of choice and plays a pivotal role in diagnosing AHLE.The purpose of this article is to make readers familiar with the typical MRI features of AHLE and to discuss differentials.CASE SUMMARY This case series reports the clinical presentation and typical neuroimaging findings in four patients diagnosed with AHLE.All patients presented with acute neurological symptoms,such as severe headaches,seizures,and altered consciousness,often following a history of fever suggesting an infectious etiology.Additionally,laboratory investigations demonstrated elevated levels of serum inflammatory markers and neutrophilic pleocytosis on cerebrospinal fluid analysis,supporting a post-infectious etiology.MRI findings consistently revealed characteristic white matter lesions with hemorrhagic foci and vasogenic edema,indicative of widespread demyelination characteristic of AHLE.The outcomes varied,with two patients surviving but experiencing neurological sequelae,while two others unfortunately succumbed to the disease.The clinical data,laboratory results,and imaging findings from this case series were systematically compared with those from previously published studies.The key similarities and differences in clinical presentation,imaging characteristics,and outcomes are presented in a tabulated format.CONCLUSION AHLE is associated with high morbidity and mortality rates,emphasizing the need for early recognition,prompt intervention,and multidisciplinary management.Further research is needed to explain the pathophysiological mechanisms underlying AHLE,identify potential biomarkers for early diagnosis,and develop targeted therapies to improve patient outcomes.
文摘Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.
基金National Natural Science Foundation of China(52375394,52275390,U23A20628,52305429)Major Project of Science and Technology in Shanxi(202301050201004)Natural Science Foundation of Shanxi Province(202403021222132)。
文摘Using multi-directional forging temperature as the independent variable and adopting the dual-mode phase field crystal model,the nucleation modes,reaction mechanisms,and interactions between grain boundaries and dislocations at different temperatures were investigated.Results show that a mapping relationship between process parameters and grain refinement/coarsening is established,and the optimal processing temperature coefficient is 0.23.Compared with the cases with processing temperature coefficient of 0.19,0.20,0.21,0.25,and 0.27,the refinement effect increases by 256.0%,146.0%,113.0%,6.7%,and 52.4%,respectively.Excessively high temperatures lead to grain coarsening due to dislocation annihilation,and the application of strain can reduce the actual melting point of materials.Even if the processing temperature does not exceed the theoretical melting point,remelting and crystallization may still occur,resulting in an overburning phenomenon that reduces internal defects and increases overall grain size.This research is of great significance for the actual forging process design.
文摘In this work,five kinds of crystals were successfully synthesized using the Czochralski method for the first time,namely Dy∶Ca_(3)Li_(0.275)Nb_(1.775)Ga_(2.95)O_(12)(CLNGG),Dy,Tb∶CLNGG,Dy,Eu∶CLNGG,Tb∶CLNGG,and Eu∶CLNGG.A detailed investigation of spectral features and energy transfer mechanisms in such crystals was conducted by analyzing their optical absorption spectra,excitation and emission spectra,and fluorescence decay curves at ambient tem-perature.Calculations based on the Judd-Ofelt theory further elucidated these features.The results demonstrate that in the Dy^(3+)system,co-doping with Tb^(3+)and Eu^(3+)ions not only enhances the emission cross-sections in the yellow wavelength re-gion but also improves the fluorescence quantum efficiency.These improvements are particularly beneficial for achieving efficient yellow light output from Dy^(3+).Additionally,the studies confirm the occurrence of reciprocal energy transfer be-tween Dy^(3+)and Tb^(3+)ions in Dy,Tb∶CLNGG crystals,whereas unidirectional energy transfer from Dy^(3+)to Eu^(3+)occurs in Dy,Eu∶CLNGG crystals.Based on the obtained research results,Dy,Tb∶CLNGG and Dy,Eu∶CLNGG crystals could be utilized as compelling and potential laser media for diode-pumped all-solid-state yellow lasers.
基金Project supported by the National Key Research and Development Program of China (Grant No. 2023YFA1406500)the National Natural Science Foundation of China (Grant Nos. 12474098, 12274388, 12174361, 12404043, and 12204004)the Natural Science Foundation of Anhui Province, China (Grant No. 2408085QA024)。
文摘The exploration and synthesis of new materials are important for materials science and condensed matter physics.Here, we report the crystal structure, magnetic properties, and electrical transport properties of the single crystals of Nd_(5)ScSb_(12), which is a quasi-one-dimensional new compound. Nd_(5)ScSb_(12) exhibits antiferromagnetic transition in both directions perpendicular and parallel to the long axis. Moreover, the magnetic field-dependent magnetization reveals two metamagnetic transitions. The electrical transport properties have been measured on the same sample but with different measurement lengths between the electrodes of the voltage. The resistivity exhibits the metallic behavior. At low temperatures, the Kondo effect and negative transverse magnetoresistance(MR)(B⊥I) have been observed. Interestingly, the measurement length has a significant impact on the Kondo effect and negative MR, providing an intuitive new approach to regulate the Kondo effect. As the measurement length increases, the Kondo effect and negative MR become more pronounced. This not only indicates that the interaction between magnetic impurities and conduction electrons dominates the electrical transport of Nd_(5)ScSb_(12) at low temperatures, but also confirms that the negative MR originates from the suppression of the Kondo effect.
基金supported by the National Natural Science Foundation of China(Nos.U23A20583,52033005,U21A2090,and 52173040)Department of Science and Technology of Sichuan Province(No.2024NSFTD0003)。
文摘Poly(_(L)-lactide)(PLLA),a leading biodegradable polyester,has demonstrated potential as a sustainable alternative,owing to its excellent biodegradability and rigidity.However,their slow crystallization kinetics and poor heat resistance limit their application scope.Recent advances have highlighted that the combination of extensional flow and thermal fields can achieve toughness–stiffness balance,high transparency,and good heat resistance.However,the effect of extensional flow on the post-non-isothermal crystallization of PLLA during heating and the resulting crystalline texture remains unclear.In this study,PLLA with a heterogeneous amorphous structure and oriented polymorph was prepared by extensional flow.The effect of heterogeneous amorphous structures on non-isothermal crystallization kinetics during the heating process was studied by thermal analysis,polarized optical microscopy,infrared spectroscopy,and ex situ/in situ X-ray characterization.These results clearly illustrate that extensional flow enhances the formation of oriented crystalline structures,accelerates non-isothermal crystallization,and modulates the polymorphic composition of PLLA.Moreover,an unexpected dual cold-crystallization behavior is identified in ordered PLLA samples upon extensional flow,which is from the extensional flow-induced heterogeneous amorphous phase into α' phase(low-temperature peak)and the pristine amorphous phase intoαphase(high-temperature peak).The extensional flow primarily promotes the formation of the more perfectαandα'phases,but has a negative effect on the final content ofαphase formed after cold crystallization andα'-to-αphase transformation.The findings of this work advance the understanding of PLLA non-isothermal crystallization after extensional flow and offer valuable guidance for high-performance PLLA upon heat treatment in practical processing.
基金supported by the National Natural Science Foundation of China under Grant No.22505100.
文摘Energetic materials face critical challenges in balancing energy density and safety,driving the development of low-sensitivity high-energy materials.Though vital for modern defense and civilian applications,low-sensitivity high-energy materials remain scarce,with 1,3,5-trinitro-2,4,6-triaminobenzene as the only deployed example.Planar lamellar energetic crystals,which utilize weak interlamellarπ-πstacking for mechanical energy dissipation,have shown significant promise.However,their rational design is constrained by insufficient understanding of intermolecular interaction synergy.This review synthesizes the structural features of planar lamellar energetic crystals,emphasizing three core elements:the single-atomic-thickness planar stacking architecture,the"strong intralamellar and weak interlamellar interaction"paradigm(key to balancing energy density and safety for low-sensitivity high-energy materials,LSHEMs),and the role of molecular planarity in reducing shear slip barriers.It categorizes design strategies into two frameworks:H–bonding dominated(single-component:cross-shaped assembly,strong H–bonding in high symmetric molecules;multi-component methods:tenon-and-mortise,acceptor-donor separation)and other intermolecular interactions(e.g.,π-πstacking-drivenπ-π2max model,π-hole recognition).Case studies in single/multi-component crystals confirm that these strategies tune interaction synergy to achieve target packing motifs.The review highlights that interaction engineering is pivotal for PLEC design,offering a targeted theoretical framework for rational development of LSHEMs(to address the scarcity of practical LSHEMs)and guiding future crystal engineering for energy-safety balanced systems.
