The electronic structures of three types of lattice defects in pyrites （i.e., As-substituted, Co-substituted, and intercrystalline Au py-rites） were calculated using the density functional theory （DFT）. In additio...The electronic structures of three types of lattice defects in pyrites （i.e., As-substituted, Co-substituted, and intercrystalline Au py-rites） were calculated using the density functional theory （DFT）. In addition, their band structures, density of states, and difference charge density were studied. The effect of the three types of lattice defects on the pyrite floatability was explored. The calculated results showed that the band-gaps of pyrites with Co-substitution and intercrystalline Au decreased significantly, which favors the oxidation of xanthate to dix-anthogen and the adsorption of dixanthogen during pyrite flotation. The stability of the pyrites increased in the following order： As-substituted 〈 perfect 〈 Co-substituted 〈 intercrystalline Au. Therefore, As-substituted pyrite is easier to be depressed by intensive oxidi-zation compared to perfect pyrite in a strongly alkaline medium. However, Co-substituted and intercrystalline Au pyrites are more difficult to be depressed compared to perfect pyrite. The analysis of the Mulliken bond population and the electron density difference indicates that the covalence characteristic of the S Fe bond is larger compared to the S S bond in perfect pyrite. In addition, the presence of the three types of lattice defects in the pyrite bulk results in an increase in the covalence level of the S Fe bond and a decrease in the covalence level of the S S bond, which affect the natural floatability of the pyrites.展开更多
2D nanomaterials are widely investigated for biomedical applications,attributed to their large specific surface area,high therapeutic loading capacity,and unique optical,thermal,and/or electronic characteristics.Latti...2D nanomaterials are widely investigated for biomedical applications,attributed to their large specific surface area,high therapeutic loading capacity,and unique optical,thermal,and/or electronic characteristics.Lattice defects affect the theranostic performance of 2D nanomaterials significantly by altering their electronic properties and chemical binding.Recent investigations have shown that defect-rich 2D nanomaterials are capable of enhancing tumor treatment through efficient drug delivery,photothermal and photodynamic therapies(PTT and PDT),and improving diagnostics via computed tomography(CT),photoacoustic and magnetic resonance imaging.This review summarizes recent progresses,including synthesis,characterization approach,and applications of defect-engineered 2D nanomaterials that are potentially useful in cancer treatment.The expert opinions are also proposed as the conclusion.展开更多
A nanosecond pulse laser source head(Nd:YAG laser,Inlite Ⅱ-20,Continuum)was equipped to a high-voltage electron microscope(HVEM,Hitachi,H-1300)to develop a laser-HVEM system at Hokkaido University.Using the laser-HVE...A nanosecond pulse laser source head(Nd:YAG laser,Inlite Ⅱ-20,Continuum)was equipped to a high-voltage electron microscope(HVEM,Hitachi,H-1300)to develop a laser-HVEM system at Hokkaido University.Using the laser-HVEM,new methods for in-situ observation on the formation process of laser-induced lattice point defects at the internal of crystalline solid are achieved;some striking phenomena and potential mechanisms are explored.In the present paper,we review our progresses on in-situ experiments of lattice defects behavior in metal using the laser-HVEM.These progresses are expected to provide insight for a broader application of laser-HVEM in scientific research.展开更多
Thermal quenching(TQ)at elevated temperature is a major factor affecting the luminescent intensity and efficiency of phosphors.Improving the thermal stability of phosphors and weakening the TQ effect are of significan...Thermal quenching(TQ)at elevated temperature is a major factor affecting the luminescent intensity and efficiency of phosphors.Improving the thermal stability of phosphors and weakening the TQ effect are of significance for the high-quality illumination of phosphor-converted WLEDs.Here,a novel red-emitting phosphor K_(2)Zn(PO_(3))_(4)∶Mn^(2+)is synthesized by standard high temperature solid state reaction in ambient atmosphere,which is a new member of self-reduction system.An effective synthesis strategy is proposed to optimize its photoluminescent performances.Combined with X-ray photoelectron spectroscopy and X-ray absorption fine structure spectroscopy,oxygen vacancy defects introduced by Mn doping are proved to play an important role in the transition of Mn^(4+)→Mn^(2+).Thermoluminescence analysis reveals that the distribution of trap levels,especially the deep ones,is effectively regulated by the controllable crystallization and significantly affect the thermal stability of phosphors.Then a defect-assisted model is proposed to address the inner mechanism of the phenomenon.The carriers trapped by deep trap levels can be released under the high-temperature stimulus,which return back to the luminescent centers and participate in the radiative recombination to improve thermal stability.This study provides a new crystallographic idea and theoretical support for obtaining luminescent materials with high thermal stability.展开更多
This communication seeks to demonstrate that, at room temperature, the deformation of the crystalline lattice can influence the process of interaction of deuterons introduced within it. Calculations of this probabilit...This communication seeks to demonstrate that, at room temperature, the deformation of the crystalline lattice can influence the process of interaction of deuterons introduced within it. Calculations of this probability, in fact, showed an increase of at least 2-3 orders of magnitude with respect to the probability of fusion on the surface of the lattice. These phenomena open the way to the theoretical hypothesis of a kind of chain reaction, as a result of the deuterium loading and catalysed by micro-cracks formed in the structure by micro-explosions, can favour the process.展开更多
Defective bulk catalysts based on TiO_(2) have superior catalytic performance for propane dehydrogenation(PDH).The oxygen vacancy concentration and the number of active sites on the catalyst surface can be effectively...Defective bulk catalysts based on TiO_(2) have superior catalytic performance for propane dehydrogenation(PDH).The oxygen vacancy concentration and the number of active sites on the catalyst surface can be effectively tuned by doping metal in TiO_(2).Herein,yttrium(Y)-doped titanium dioxide(nY/TiO_(x))catalysts were in-situ synthesized via the coprecipitation method to study the effect of rare earth metal Y doping on the structure of TiO_(2) and the catalytic performance for PDH.Experimental results demonstrate that Ydoped TiO_(2) exhibits higher catalytic activity,propylene selectivity and stability than bare TiO_(2).Full characterizations with X-ray diffraction(XRD),high-resolution transmission electron microscope(HRTEM),X-ray photoelectron spectroscopy(XPS),infrared spectroscopy of pyridine adsorption(Py-IR),temperature-programmed desorption of ammonia(NH_(3)-TPD),H_(2) temperature-programmed reduction(H_2-TPR),and Raman techniques on these catalysts reveal that Y^(3+)can enter TiO_(2) lattice,and the lattice stability of the catalyst can be enhanced by replacing Ti^(4+)to form Y-O-Ti structure.Meanwhile,the introduction of an appropriate amount of Y can obviously promote the PDH reaction by adjusting the acidity of the catalyst,improving the release capacity of TiO_(2) lattice oxygen and increasing the formation of active centers.Nevertheless,excessive Y doping will lead to pore clogging,and the exposure of active sites will be reduced,resulting in the degradation of catalytic performance.展开更多
The Cu/ZnO catalyst formed upon the calcination of aurichalcite has a uniform distribution of ZnO,which can delay the sintering of Cu species at high temperatures.In this study,aurichalcite possessing a nearly pure ph...The Cu/ZnO catalyst formed upon the calcination of aurichalcite has a uniform distribution of ZnO,which can delay the sintering of Cu species at high temperatures.In this study,aurichalcite possessing a nearly pure phase was prepared using the ammonium complex dissociation precipitation method,and the effect of calcination temperature on the structure and surface properties of the derived Cu/ZnO catalyst was studied.The results show that the calcination temperature determines the particle size and crystallization degree of the Cu/ZnO catalyst and the surface properties of the corresponding copper oxide and reduced copper.Low-temperature calcination is more conducive to reducing the particle size of the Cu/ZnO catalyst,increasing the specific surface area,and generating abundant defect characteristics on the surface,which is key to obtaining highly dispersed copper and copper-specific surface area catalysts by subsequent reduction.Additionally,the Cu/ZnO catalyst derived using a 300℃or 400℃calcination proved to have a higher specific activity per gram of copper than a commercial Cu/Zn/Al catalyst.The discovery in this study opens up a new method for the convenient preparation of a high-temperature resistant Cu/Zn methanol reforming catalyst.展开更多
Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Un...Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Under the 394 nm excitation,Cs_3Zn_(5.94)B_9O_(21):0.06Eu^(3+)possesses two characteristic emissions peaked at 591 and 612 nm with limited thermal stability.By introducing Li^(+)ions into the lattice,the sample exhibits high color purity and excellent zero-thermal quenching because the defect contents of the phosphor can be effectively modulated via charge-compensation effect.Then,under the stimulus of high temperature,the corresponding trap levels with a suitable depth(E=1.27 eV)will release electrons to recombine with the luminescent centers,compensating for the energy loss.The study provides a meaningful guide for optimizing and designing novel functional photoluminescent materials.展开更多
The multiple quantum transitions within d-band correlation oxides such as rare-earth nickelates(RENiO_(3))triggered by critical temperatures and/or hydrogenation opened up a new paradigm for correlated electronics app...The multiple quantum transitions within d-band correlation oxides such as rare-earth nickelates(RENiO_(3))triggered by critical temperatures and/or hydrogenation opened up a new paradigm for correlated electronics applications,e.g.ocean electric field sensor,bio-sensor,and neuron synapse logical devices.Nevertheless,these applications are obstructed by the present ineffectiveness in the thin film growth of the metastable RENiO_(3)with flexibly adjustable rare-earth compositions and electronic structures.Herein,we demonstrate a metal-organic decompositions(MOD)approach that can effectively grow metastable RENiO_(3)covering a large variety of the rare-earth composition without introducing any vacuum process.Unlike the previous chemical growths for RENiO_(3)relying on strict interfacial coherency that limit the film thickness,the MOD growth using reactive isooctanoate percussors is tolerant to lattice defects and therefore achieves comparable film thickness to vacuum depositions.Further indicated by positron annihilation spectroscopy,the RENiO_(3)grown by MOD exhibit large amount of lattice defects that improves their hydrogen incorporation amount and electron transfers,as demonstrated by the resonant nuclear reaction analysis and near edge X-ray absorption fine structure analysis.This effectively enlarges the magnitude in the resistance regulations in particular for RENiO_(3)with lighter RE,shedding a light on the extrinsic regulation of the hydrogen induced quantum transitions for correlated oxides semiconductors kinetically via defect engineering.展开更多
Two-dimensional (2D)Ni(OH)_(2) nanosheets can theoretically expose their active sites of 100%.Whereas,their intrinsic easy accumulation and low conductivity lead to weak and unsustainable reaction kinetics.Herein,we p...Two-dimensional (2D)Ni(OH)_(2) nanosheets can theoretically expose their active sites of 100%.Whereas,their intrinsic easy accumulation and low conductivity lead to weak and unsustainable reaction kinetics.Herein,we propose a novel halogen chlorine-triggered electrochemical etching strategy to controllably manage the reaction kinetics of 2D Ni(OH)_(2) nanosheets(EE/Cl-Ni(OH)_(2)).It is found that halogen chlorine doping can adjust the interlamellar spacing flexibly and promote the lattice oxygen activation to achieve controlled construction of superficial oxygen defects at the adjustable voltage.The optimal EE/Cl-Ni(OH)_(2) electrode exhibits a high rate capability and excellent specific capacity of 206.9 mA h g^(-1) at 1 A g^(-1) in a three-electrode system,which is more than twice as high as the pristine Ni(OH)_(2).Furthermore,EE/Cl-Ni(OH)_(2) cathode and FeOOH@rGO anode are employed for developing an aqueous Ni-Fe battery with an excellent energy density of 83 W h kg^(-1),a high power density of 17051 W kg^(-1),and robust durability over 20,000 cycles.This strategy exploits a fresh channel for the ingenious fabrication of highefficiency and stable nickel-based deficiency materials for energy storage.展开更多
Four manganese oxide (MnO_(x)) catalysts with different phases were prepared via a hydrothermal method, and the toluene oxidation over the four manganese dioxide (MnO_(x)) catalysts was studied. Among the catalysts, ...Four manganese oxide (MnO_(x)) catalysts with different phases were prepared via a hydrothermal method, and the toluene oxidation over the four manganese dioxide (MnO_(x)) catalysts was studied. Among the catalysts, δ-MnO_(2) exhibits the best performance, excellent stability, and reusability. Moreover, δ-MnO_(2) possesses the highest specific surface area, with more exposed active sites compared to the other catalysts with which to make contact with toluene, leading to it exhibiting excellent activity. Furthermore, δ-MnO_(2) shows more lattice defects, Mn^(3+)/(Mn^(3+) + Mn^(4+)), oxygen vacancies, and surface adsorbed oxygen than the other catalysts, resulting in its excellent redox properties and catalytic performance. In addition, oxygen molecules adsorb on the oxygen vacancies of δ-MnO_(2), which are beneficial to the adsorption and oxidation of toluene, with benzyl alcohol, benzaldehyde, benzoic acid, and benzoic acid ester detected as specific intermediate products.展开更多
Ti-based hydrogen storage alloy is one of the most common solid-state hydrogen storage materials due to its high hydrogen absorption capacity, low dehydrogenation temperature and rich resources. This paper mainly pres...Ti-based hydrogen storage alloy is one of the most common solid-state hydrogen storage materials due to its high hydrogen absorption capacity, low dehydrogenation temperature and rich resources. This paper mainly presents the influence of several different preparation methods of Ti-based hydrogen storage alloys on the hydrogen storage performance including traditional preparation methods (smelting, rapid quenching and mechanical alloying) and novel methods by plastic deformation (cold rolling, equal channel angular pressing and high-pressure torsion). The microstructure analysis and hydrogen storage properties of Ti-based alloy are summarized thoroughly corresponding with the preparation processes mentioned above. It was found that slight introduction of lattice defects including dislocation, grain boundary, sub-grain boundary and cracks by severe plastic deformation (SPD) was beneficial to improve the hydriding/dehydriding kinetic characteristic. However, the nonuniform composition and residual stress of the alloy may be caused by SPD, which is not conducive to the improvement of hydrogen storage capacity. In the future, it would be expected that new methods and technologies combined with dopant and modification are applied to Ti-based hydrogen storage alloys to make breakthroughs in practical application.展开更多
The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pel...The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pellets require higher preheating temperature and longer preheating time to attain required compression strength of pellets compared with the common magnetite oxidized pellets. It is found that when the hematite concentrates are pretreated by high pressure roll grinding （HPRG）, the compression strengths of preheated and roasted oxidized hematite pellets get improved even with lower preheating and roasting temperatures and shorter preheating and roasting time. The mechanism for HPRG to improve roasting properties of oxidized pellets were investigated and the cause mainly lies in the increase of micro-sized particles and the decrease of dispersion degree for hematite concentrates, which promotes the hematite concentrate particles to be compacted, the solid-phase crystallization, and finally the formation of Fe203 bonding bridges during subsequent high temperature roasting process.展开更多
NiMnO3 perovskite catalysts supported on cordierite modified by CexZr（1-x）O2 coatings were prepared using impregnation and sol-gel methods for catalytic combustion of single/double component VOCs at different concen...NiMnO3 perovskite catalysts supported on cordierite modified by CexZr（1-x）O2 coatings were prepared using impregnation and sol-gel methods for catalytic combustion of single/double component VOCs at different concentrations and GHSV of 15,000 h^（-1）, which were characterized by BET, XRD, SEM, FT-IR, H2-TPR and O2-TPD. After coating modification, the specific surface area of catalysts is improved obviously.Among the catalysts, the Ce（0.75）Zr（0.25）O2 coating modified NiMnO3 catalyst exhibits the best catalytic activity for VOCs combustion with 95.6% conversion at 275 ℃ and has stable activity when catalyst is embalmed at 800 ℃. In addition, the catalyst also presents the excellent water-resistant and conversion stability over time-on-stream condition. The reason is that Ce（0.75）Zr（0.25）O2 coating can promote more lattice distortion and defects and smaller crystal size, which improve oxygen transfer capability and dispersion of active component.展开更多
Shrinkage porosity is a type of random distribution defects and exists in most large castings. Different from the periodic symmetry defects or certain distribution defects, shrinkage porosity presents a random "c...Shrinkage porosity is a type of random distribution defects and exists in most large castings. Different from the periodic symmetry defects or certain distribution defects, shrinkage porosity presents a random "cloud-like" configuration, which brings difficulties in quantifying the effective performance of defected casting. In this paper, the influences of random shrinkage porosity on the equivalent elastic modulus of QT400-18 casting were studied by a numerical statistics approach. An improved random algorithm was applied into the lattice model to simulate the "cloud-like" morphology of shrinkage porosity. Then, a large number of numerical samples containing random levels of shrinkage were generated by the proposed algorithm. The stress concentration factor and equivalent elastic modulus of these numerical samples were calculated. Based on a statistical approach, the effects of shrinkage porosity's distribution characteristics, such as area fraction, shape, and relative location on the casting's equivalent mechanical properties were discussed respectively. It is shown that the approach with randomly distributed defects has better predictive capabilities than traditional methods. The following conclusions can be drawn from the statistical simulations:(1) the effective modulus decreases remarkably if the shrinkage porosity percent is greater than 1.5%;(2) the average Stress Concentration Factor(SCF) produced by shrinkage porosity is about 2.0;(3) the defect's length across the loading direction plays a more important role in the effective modulus than the length along the loading direction;(4) the surface defect perpendicular to loading direction reduces the mean modulus about 1.5% more than a defect of other position.展开更多
Introducing topological lattice defects,such as dislocations,into topological photonic crystals enables the emergence of many interesting phenomena,including robust bound states and fractional charges.Previous studies...Introducing topological lattice defects,such as dislocations,into topological photonic crystals enables the emergence of many interesting phenomena,including robust bound states and fractional charges.Previous studies have primarily focused on the realization of dislocation modes within a single band gap,which limits the number of dislocation modes and their applications.展开更多
The electrocaloric effect(ECE)offers a pathway to environmentally sustainable and easily miniaturized refrigeration technology,positioning it as a front-runner for the next generation of solid-state cooling solutions....The electrocaloric effect(ECE)offers a pathway to environmentally sustainable and easily miniaturized refrigeration technology,positioning it as a front-runner for the next generation of solid-state cooling solutions.This research unveils a remarkable ECE in afinely tuned(Ba_(0.86)Ca_(0.14))_(0.98)La_(0.02)Ti_(0.92)Sn_(0.08)O_(3)ceramic,exhibiting a temperature shift(DT)of 1.6 K across more than 85%of the maximumΔT(ΔT_(max))and spanning an exceptionally wide operational range of 92 K.Our investigation on dielectric responses and ferroelectric polarization-electricfield(PeE)loops suggests that the broad operational scope results from the fragmentation of extended ferroelectric domains into smaller domains and polar nano-regions(PNRs)supported by PFM analysis.Furthermore,the introduction of La enhances spontaneous polarization by significantly extending the maximum electricfield that can be applied,facilitating highperformance ECE at ambient temperature.This study positions BaTiO_(3)-based lead-free ceramic as a sustainable alternative for addressing the cooling demands of modern electronic components,marking a significant stride toward next-generation solid-state refrigeration.展开更多
As a novel material,high-entropy compounds have attracted extensive attention in the field of lithium–sulfur battery host materials due to their diverse elemental composition with a wide range of properties.The abili...As a novel material,high-entropy compounds have attracted extensive attention in the field of lithium–sulfur battery host materials due to their diverse elemental composition with a wide range of properties.The ability to effectively mitigate the shuttle effect of lithium polysulfides and catalyze the bidirectional conversion of Li_(2)S_(2)/Li_(2)S is crucial to enhance the overall performance of the battery.In this study,a unique sulfur host nanosized highentropy material comprising selenium-doped HEO(AlCrFeCoNi)_(3)O_(4-x)-Se_(x)is fabricated using an in situ thermal reduction and selenylation method.In the high-entropy compounds,the introduction of Se causes that the generation of oxygen vacancies during the lattice distortion serves as ion transfer pathway and the formation of M-Se bonds provides a high adsorption capability for LiPSs.Moreover,the polymetallic cooperative high-entropy nanoparticles also provide numerous active sites favoring redox kinetics of the sulfur electrode.The resulting selenium-doped HEO(AlCrFeCoNi)_(3)O_(4-x)-Se_(x)not only enhances discharge capacity but also maintains excellent capacity cycling stability.As a result,the HEO-Se/S composite exhibits a specific capacity of 1233.9 mAh g^(-1)at 0.1C and experiences minimal capacity fading at a rate of 0.038%per cycle over 500 cycles at 0.2C,while host materials with sulfur loading of 4.33 mg cm^(-2)and E/S ratio of 5.88μL mg^(-1)exhibit excellent capacity retention after 100 cycles at 0.2C.This work offers new insights into synthesizing high-entropy nanomaterials for improving the electrochemical performance of Li–S batteries.展开更多
Tungsten has promising applications in high-radiation,high-erosion and high-impact environments.Laser peening is an effective method to enhance the surface mechanical properties of tungsten materials.However,the ultra...Tungsten has promising applications in high-radiation,high-erosion and high-impact environments.Laser peening is an effective method to enhance the surface mechanical properties of tungsten materials.However,the ultrafast dynamic mechanism of defect evolutions induced by laser shockwave in tungsten lattice is unclear.Here,we investigated the evolutions and interactions of various defects under ultrafast compressive process in tungsten lattice using molecular dynamic method.The results confirm the brittleness of tungsten and reveal that void can reduce the yield strain and strength of the tungsten lattice by accelerating defect mesh extension and promoting the dislocation nucleation around itself.Dislocation density is increased with compressive strain rate.Meanwhile,dislocation multiplication and motion reduce the elastic stage and play a dominant role during the plastic deformation of tungsten lattice.Additionally,void can disrupt the dislocation displacement and promote the pinning effect on dislocations by defect mesh extension.展开更多
Less-expensive but efficient electrocatalysts are essential to accelerate the commercialization of fuel cells.Herein,ultrathin PdPb nanowires(PdPb NWs)with a diameter of around 3.5 nm were prepared by using a one-step...Less-expensive but efficient electrocatalysts are essential to accelerate the commercialization of fuel cells.Herein,ultrathin PdPb nanowires(PdPb NWs)with a diameter of around 3.5 nm were prepared by using a one-step hydrothermal method.The introduction of Pb in Pd-based bimetallic nanostructures produced high differences in the morphology from Pd nanoparticles(NPs)to various PdPb NWs.All the as-prepared PdPb NWs exhibited better electrocatalytic activity and durability than Pd NPs due to the synergistic effect.Especially,Pd65Pb35 possessed the highest current density of about 3460 mA mgPd^−1 for the ethanol electrooxidation which was around 6.3 times higher than commercial Pd/C.The high-performance of Pd65Pb35 is attributed to the defect-rich and stable nanowire structure with optimized surface atomic arrangement,as evidenced by high resolution transmission electron microscopy measurements and long-time treatment in an acidic media.The differences in the morphologies and electrocatalytic activities of PdPb NWs with varied Pb contents have also been discussed and analyzed.展开更多
基金supported by the National Natural Science Foundation of China (No.u0837602)
文摘The electronic structures of three types of lattice defects in pyrites （i.e., As-substituted, Co-substituted, and intercrystalline Au py-rites） were calculated using the density functional theory （DFT）. In addition, their band structures, density of states, and difference charge density were studied. The effect of the three types of lattice defects on the pyrite floatability was explored. The calculated results showed that the band-gaps of pyrites with Co-substitution and intercrystalline Au decreased significantly, which favors the oxidation of xanthate to dix-anthogen and the adsorption of dixanthogen during pyrite flotation. The stability of the pyrites increased in the following order： As-substituted 〈 perfect 〈 Co-substituted 〈 intercrystalline Au. Therefore, As-substituted pyrite is easier to be depressed by intensive oxidi-zation compared to perfect pyrite in a strongly alkaline medium. However, Co-substituted and intercrystalline Au pyrites are more difficult to be depressed compared to perfect pyrite. The analysis of the Mulliken bond population and the electron density difference indicates that the covalence characteristic of the S Fe bond is larger compared to the S S bond in perfect pyrite. In addition, the presence of the three types of lattice defects in the pyrite bulk results in an increase in the covalence level of the S Fe bond and a decrease in the covalence level of the S S bond, which affect the natural floatability of the pyrites.
基金financial support by Australian Research Council(ARC)Discovery Project(DPI90103486).
文摘2D nanomaterials are widely investigated for biomedical applications,attributed to their large specific surface area,high therapeutic loading capacity,and unique optical,thermal,and/or electronic characteristics.Lattice defects affect the theranostic performance of 2D nanomaterials significantly by altering their electronic properties and chemical binding.Recent investigations have shown that defect-rich 2D nanomaterials are capable of enhancing tumor treatment through efficient drug delivery,photothermal and photodynamic therapies(PTT and PDT),and improving diagnostics via computed tomography(CT),photoacoustic and magnetic resonance imaging.This review summarizes recent progresses,including synthesis,characterization approach,and applications of defect-engineered 2D nanomaterials that are potentially useful in cancer treatment.The expert opinions are also proposed as the conclusion.
基金supported by the National Natural Science Foundation of China(No.51471027)。
文摘A nanosecond pulse laser source head(Nd:YAG laser,Inlite Ⅱ-20,Continuum)was equipped to a high-voltage electron microscope(HVEM,Hitachi,H-1300)to develop a laser-HVEM system at Hokkaido University.Using the laser-HVEM,new methods for in-situ observation on the formation process of laser-induced lattice point defects at the internal of crystalline solid are achieved;some striking phenomena and potential mechanisms are explored.In the present paper,we review our progresses on in-situ experiments of lattice defects behavior in metal using the laser-HVEM.These progresses are expected to provide insight for a broader application of laser-HVEM in scientific research.
文摘Thermal quenching(TQ)at elevated temperature is a major factor affecting the luminescent intensity and efficiency of phosphors.Improving the thermal stability of phosphors and weakening the TQ effect are of significance for the high-quality illumination of phosphor-converted WLEDs.Here,a novel red-emitting phosphor K_(2)Zn(PO_(3))_(4)∶Mn^(2+)is synthesized by standard high temperature solid state reaction in ambient atmosphere,which is a new member of self-reduction system.An effective synthesis strategy is proposed to optimize its photoluminescent performances.Combined with X-ray photoelectron spectroscopy and X-ray absorption fine structure spectroscopy,oxygen vacancy defects introduced by Mn doping are proved to play an important role in the transition of Mn^(4+)→Mn^(2+).Thermoluminescence analysis reveals that the distribution of trap levels,especially the deep ones,is effectively regulated by the controllable crystallization and significantly affect the thermal stability of phosphors.Then a defect-assisted model is proposed to address the inner mechanism of the phenomenon.The carriers trapped by deep trap levels can be released under the high-temperature stimulus,which return back to the luminescent centers and participate in the radiative recombination to improve thermal stability.This study provides a new crystallographic idea and theoretical support for obtaining luminescent materials with high thermal stability.
文摘This communication seeks to demonstrate that, at room temperature, the deformation of the crystalline lattice can influence the process of interaction of deuterons introduced within it. Calculations of this probability, in fact, showed an increase of at least 2-3 orders of magnitude with respect to the probability of fusion on the surface of the lattice. These phenomena open the way to the theoretical hypothesis of a kind of chain reaction, as a result of the deuterium loading and catalysed by micro-cracks formed in the structure by micro-explosions, can favour the process.
基金Project supported by the National Natural Science Foundation of China(22172192,92145301)National Key Research and Development Program(2021YFB3500603)。
文摘Defective bulk catalysts based on TiO_(2) have superior catalytic performance for propane dehydrogenation(PDH).The oxygen vacancy concentration and the number of active sites on the catalyst surface can be effectively tuned by doping metal in TiO_(2).Herein,yttrium(Y)-doped titanium dioxide(nY/TiO_(x))catalysts were in-situ synthesized via the coprecipitation method to study the effect of rare earth metal Y doping on the structure of TiO_(2) and the catalytic performance for PDH.Experimental results demonstrate that Ydoped TiO_(2) exhibits higher catalytic activity,propylene selectivity and stability than bare TiO_(2).Full characterizations with X-ray diffraction(XRD),high-resolution transmission electron microscope(HRTEM),X-ray photoelectron spectroscopy(XPS),infrared spectroscopy of pyridine adsorption(Py-IR),temperature-programmed desorption of ammonia(NH_(3)-TPD),H_(2) temperature-programmed reduction(H_2-TPR),and Raman techniques on these catalysts reveal that Y^(3+)can enter TiO_(2) lattice,and the lattice stability of the catalyst can be enhanced by replacing Ti^(4+)to form Y-O-Ti structure.Meanwhile,the introduction of an appropriate amount of Y can obviously promote the PDH reaction by adjusting the acidity of the catalyst,improving the release capacity of TiO_(2) lattice oxygen and increasing the formation of active centers.Nevertheless,excessive Y doping will lead to pore clogging,and the exposure of active sites will be reduced,resulting in the degradation of catalytic performance.
基金the Chongzuo City Science and Technology Plan Project(Chongke20220608)the Guangxi Key Research and Development Plan Project(GuikeAB21220027).
文摘The Cu/ZnO catalyst formed upon the calcination of aurichalcite has a uniform distribution of ZnO,which can delay the sintering of Cu species at high temperatures.In this study,aurichalcite possessing a nearly pure phase was prepared using the ammonium complex dissociation precipitation method,and the effect of calcination temperature on the structure and surface properties of the derived Cu/ZnO catalyst was studied.The results show that the calcination temperature determines the particle size and crystallization degree of the Cu/ZnO catalyst and the surface properties of the corresponding copper oxide and reduced copper.Low-temperature calcination is more conducive to reducing the particle size of the Cu/ZnO catalyst,increasing the specific surface area,and generating abundant defect characteristics on the surface,which is key to obtaining highly dispersed copper and copper-specific surface area catalysts by subsequent reduction.Additionally,the Cu/ZnO catalyst derived using a 300℃or 400℃calcination proved to have a higher specific activity per gram of copper than a commercial Cu/Zn/Al catalyst.The discovery in this study opens up a new method for the convenient preparation of a high-temperature resistant Cu/Zn methanol reforming catalyst.
基金the National Natural Science Foundation of China(11774187,U1902218)National Key R&D Program of China(2018YFE0203400)+1 种基金Natural Science Foundation of Tianjin city(19JCYBJC17600)111 Project(B07013)。
文摘Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Under the 394 nm excitation,Cs_3Zn_(5.94)B_9O_(21):0.06Eu^(3+)possesses two characteristic emissions peaked at 591 and 612 nm with limited thermal stability.By introducing Li^(+)ions into the lattice,the sample exhibits high color purity and excellent zero-thermal quenching because the defect contents of the phosphor can be effectively modulated via charge-compensation effect.Then,under the stimulus of high temperature,the corresponding trap levels with a suitable depth(E=1.27 eV)will release electrons to recombine with the luminescent centers,compensating for the energy loss.The study provides a meaningful guide for optimizing and designing novel functional photoluminescent materials.
基金financially supported by the National Key Research and Development Program of China(No.2021YFA0718900)National Natural Science Foundation of China(Nos.62074014,52073090,and 52103284)。
文摘The multiple quantum transitions within d-band correlation oxides such as rare-earth nickelates(RENiO_(3))triggered by critical temperatures and/or hydrogenation opened up a new paradigm for correlated electronics applications,e.g.ocean electric field sensor,bio-sensor,and neuron synapse logical devices.Nevertheless,these applications are obstructed by the present ineffectiveness in the thin film growth of the metastable RENiO_(3)with flexibly adjustable rare-earth compositions and electronic structures.Herein,we demonstrate a metal-organic decompositions(MOD)approach that can effectively grow metastable RENiO_(3)covering a large variety of the rare-earth composition without introducing any vacuum process.Unlike the previous chemical growths for RENiO_(3)relying on strict interfacial coherency that limit the film thickness,the MOD growth using reactive isooctanoate percussors is tolerant to lattice defects and therefore achieves comparable film thickness to vacuum depositions.Further indicated by positron annihilation spectroscopy,the RENiO_(3)grown by MOD exhibit large amount of lattice defects that improves their hydrogen incorporation amount and electron transfers,as demonstrated by the resonant nuclear reaction analysis and near edge X-ray absorption fine structure analysis.This effectively enlarges the magnitude in the resistance regulations in particular for RENiO_(3)with lighter RE,shedding a light on the extrinsic regulation of the hydrogen induced quantum transitions for correlated oxides semiconductors kinetically via defect engineering.
基金supported by the Opening Project of State Key Laboratory of Advanced Chemical Power Sourcesthe Guizhou Provincial Science and Technology Projects(QKHJC-ZK[2021]YB057)+1 种基金the Growth Project of Young Scientific and Technological Talents in Colleges and Universities of Guizhou Province(QKHJCKYZ[2021]252)the Reward and Subsidy Fund Project of Guizhou Education University(Z20210108)。
文摘Two-dimensional (2D)Ni(OH)_(2) nanosheets can theoretically expose their active sites of 100%.Whereas,their intrinsic easy accumulation and low conductivity lead to weak and unsustainable reaction kinetics.Herein,we propose a novel halogen chlorine-triggered electrochemical etching strategy to controllably manage the reaction kinetics of 2D Ni(OH)_(2) nanosheets(EE/Cl-Ni(OH)_(2)).It is found that halogen chlorine doping can adjust the interlamellar spacing flexibly and promote the lattice oxygen activation to achieve controlled construction of superficial oxygen defects at the adjustable voltage.The optimal EE/Cl-Ni(OH)_(2) electrode exhibits a high rate capability and excellent specific capacity of 206.9 mA h g^(-1) at 1 A g^(-1) in a three-electrode system,which is more than twice as high as the pristine Ni(OH)_(2).Furthermore,EE/Cl-Ni(OH)_(2) cathode and FeOOH@rGO anode are employed for developing an aqueous Ni-Fe battery with an excellent energy density of 83 W h kg^(-1),a high power density of 17051 W kg^(-1),and robust durability over 20,000 cycles.This strategy exploits a fresh channel for the ingenious fabrication of highefficiency and stable nickel-based deficiency materials for energy storage.
基金supported by the National Natural Science Foundation of China (No. 21872096)the Natural Science Youth Fund of Henan Province (No. 202300410034)+3 种基金the Young Teacher Foundation of Henan University of Urban Construction (No. YCJQNGGJS201903)the Key Scientific and Technological Project of Henan Province (No. 182102311016)the Henan Key Scientific Research Projects (No. 20A610003)the Doctoral Research Start-up Project of Henan University of Urban Construction (No. 990/Q2017011)
文摘Four manganese oxide (MnO_(x)) catalysts with different phases were prepared via a hydrothermal method, and the toluene oxidation over the four manganese dioxide (MnO_(x)) catalysts was studied. Among the catalysts, δ-MnO_(2) exhibits the best performance, excellent stability, and reusability. Moreover, δ-MnO_(2) possesses the highest specific surface area, with more exposed active sites compared to the other catalysts with which to make contact with toluene, leading to it exhibiting excellent activity. Furthermore, δ-MnO_(2) shows more lattice defects, Mn^(3+)/(Mn^(3+) + Mn^(4+)), oxygen vacancies, and surface adsorbed oxygen than the other catalysts, resulting in its excellent redox properties and catalytic performance. In addition, oxygen molecules adsorb on the oxygen vacancies of δ-MnO_(2), which are beneficial to the adsorption and oxidation of toluene, with benzyl alcohol, benzaldehyde, benzoic acid, and benzoic acid ester detected as specific intermediate products.
文摘Ti-based hydrogen storage alloy is one of the most common solid-state hydrogen storage materials due to its high hydrogen absorption capacity, low dehydrogenation temperature and rich resources. This paper mainly presents the influence of several different preparation methods of Ti-based hydrogen storage alloys on the hydrogen storage performance including traditional preparation methods (smelting, rapid quenching and mechanical alloying) and novel methods by plastic deformation (cold rolling, equal channel angular pressing and high-pressure torsion). The microstructure analysis and hydrogen storage properties of Ti-based alloy are summarized thoroughly corresponding with the preparation processes mentioned above. It was found that slight introduction of lattice defects including dislocation, grain boundary, sub-grain boundary and cracks by severe plastic deformation (SPD) was beneficial to improve the hydriding/dehydriding kinetic characteristic. However, the nonuniform composition and residual stress of the alloy may be caused by SPD, which is not conducive to the improvement of hydrogen storage capacity. In the future, it would be expected that new methods and technologies combined with dopant and modification are applied to Ti-based hydrogen storage alloys to make breakthroughs in practical application.
基金Project(50725416) supported by the National Natural Science Funds for Distinguished Young Scholars of China
文摘The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pellets require higher preheating temperature and longer preheating time to attain required compression strength of pellets compared with the common magnetite oxidized pellets. It is found that when the hematite concentrates are pretreated by high pressure roll grinding （HPRG）, the compression strengths of preheated and roasted oxidized hematite pellets get improved even with lower preheating and roasting temperatures and shorter preheating and roasting time. The mechanism for HPRG to improve roasting properties of oxidized pellets were investigated and the cause mainly lies in the increase of micro-sized particles and the decrease of dispersion degree for hematite concentrates, which promotes the hematite concentrate particles to be compacted, the solid-phase crystallization, and finally the formation of Fe203 bonding bridges during subsequent high temperature roasting process.
基金Project supported by the Science and Technology Department of Jiangsu Province(BE2016769)the Natural Science Foundation of China(51172107)+2 种基金Natural Science Foundation of the Jiangsu Higher Education Institutions of China(14KJB430014)Open fund by Jiangsu Engineering Technology Research Center of Environmental Cleaning Materials(KFK1503)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘NiMnO3 perovskite catalysts supported on cordierite modified by CexZr（1-x）O2 coatings were prepared using impregnation and sol-gel methods for catalytic combustion of single/double component VOCs at different concentrations and GHSV of 15,000 h^（-1）, which were characterized by BET, XRD, SEM, FT-IR, H2-TPR and O2-TPD. After coating modification, the specific surface area of catalysts is improved obviously.Among the catalysts, the Ce（0.75）Zr（0.25）O2 coating modified NiMnO3 catalyst exhibits the best catalytic activity for VOCs combustion with 95.6% conversion at 275 ℃ and has stable activity when catalyst is embalmed at 800 ℃. In addition, the catalyst also presents the excellent water-resistant and conversion stability over time-on-stream condition. The reason is that Ce（0.75）Zr（0.25）O2 coating can promote more lattice distortion and defects and smaller crystal size, which improve oxygen transfer capability and dispersion of active component.
基金supported by the National Natural Science Foundation of China(Grant No.51305350)the Basic Research Foundation of NWPU(No.3102014JCQ01045)
文摘Shrinkage porosity is a type of random distribution defects and exists in most large castings. Different from the periodic symmetry defects or certain distribution defects, shrinkage porosity presents a random "cloud-like" configuration, which brings difficulties in quantifying the effective performance of defected casting. In this paper, the influences of random shrinkage porosity on the equivalent elastic modulus of QT400-18 casting were studied by a numerical statistics approach. An improved random algorithm was applied into the lattice model to simulate the "cloud-like" morphology of shrinkage porosity. Then, a large number of numerical samples containing random levels of shrinkage were generated by the proposed algorithm. The stress concentration factor and equivalent elastic modulus of these numerical samples were calculated. Based on a statistical approach, the effects of shrinkage porosity's distribution characteristics, such as area fraction, shape, and relative location on the casting's equivalent mechanical properties were discussed respectively. It is shown that the approach with randomly distributed defects has better predictive capabilities than traditional methods. The following conclusions can be drawn from the statistical simulations:(1) the effective modulus decreases remarkably if the shrinkage porosity percent is greater than 1.5%;(2) the average Stress Concentration Factor(SCF) produced by shrinkage porosity is about 2.0;(3) the defect's length across the loading direction plays a more important role in the effective modulus than the length along the loading direction;(4) the surface defect perpendicular to loading direction reduces the mean modulus about 1.5% more than a defect of other position.
基金National Natural Science Foundation of China(12204552, 12064025, 12374364, 62305146)Basic and Applied Basic Research Foundation of Guangdong Province(2023B1515040023)+3 种基金Training Program for Academic and Technical Leaders of Major Disciplines in Jiangxi Province(20243BCE51163)Natural Science Foundation of Jiangxi Province (20242BAB20023, 20232BAB211031)Nanchang University Youth Training Program (PYQN20230064)Jiangxi Provincial Key Laboratory of Photodetectors(2024SSY03041)
文摘Introducing topological lattice defects,such as dislocations,into topological photonic crystals enables the emergence of many interesting phenomena,including robust bound states and fractional charges.Previous studies have primarily focused on the realization of dislocation modes within a single band gap,which limits the number of dislocation modes and their applications.
基金the Science and Technology Plan of Guangxi(Nos.AA23023027,AB24010230)the Key Research and Development Program of Shandong Province(2022CXGC020203)+1 种基金the Natural Science Foundation of China(Grant No.12264012,62271362,12304120)the Science and Technology Plan of Guilin(2022H03 and ZY20220101).
文摘The electrocaloric effect(ECE)offers a pathway to environmentally sustainable and easily miniaturized refrigeration technology,positioning it as a front-runner for the next generation of solid-state cooling solutions.This research unveils a remarkable ECE in afinely tuned(Ba_(0.86)Ca_(0.14))_(0.98)La_(0.02)Ti_(0.92)Sn_(0.08)O_(3)ceramic,exhibiting a temperature shift(DT)of 1.6 K across more than 85%of the maximumΔT(ΔT_(max))and spanning an exceptionally wide operational range of 92 K.Our investigation on dielectric responses and ferroelectric polarization-electricfield(PeE)loops suggests that the broad operational scope results from the fragmentation of extended ferroelectric domains into smaller domains and polar nano-regions(PNRs)supported by PFM analysis.Furthermore,the introduction of La enhances spontaneous polarization by significantly extending the maximum electricfield that can be applied,facilitating highperformance ECE at ambient temperature.This study positions BaTiO_(3)-based lead-free ceramic as a sustainable alternative for addressing the cooling demands of modern electronic components,marking a significant stride toward next-generation solid-state refrigeration.
基金supported by Jilin Province Science and Technology Development Project(Nos.20250102158JC,20240302035GX)
文摘As a novel material,high-entropy compounds have attracted extensive attention in the field of lithium–sulfur battery host materials due to their diverse elemental composition with a wide range of properties.The ability to effectively mitigate the shuttle effect of lithium polysulfides and catalyze the bidirectional conversion of Li_(2)S_(2)/Li_(2)S is crucial to enhance the overall performance of the battery.In this study,a unique sulfur host nanosized highentropy material comprising selenium-doped HEO(AlCrFeCoNi)_(3)O_(4-x)-Se_(x)is fabricated using an in situ thermal reduction and selenylation method.In the high-entropy compounds,the introduction of Se causes that the generation of oxygen vacancies during the lattice distortion serves as ion transfer pathway and the formation of M-Se bonds provides a high adsorption capability for LiPSs.Moreover,the polymetallic cooperative high-entropy nanoparticles also provide numerous active sites favoring redox kinetics of the sulfur electrode.The resulting selenium-doped HEO(AlCrFeCoNi)_(3)O_(4-x)-Se_(x)not only enhances discharge capacity but also maintains excellent capacity cycling stability.As a result,the HEO-Se/S composite exhibits a specific capacity of 1233.9 mAh g^(-1)at 0.1C and experiences minimal capacity fading at a rate of 0.038%per cycle over 500 cycles at 0.2C,while host materials with sulfur loading of 4.33 mg cm^(-2)and E/S ratio of 5.88μL mg^(-1)exhibit excellent capacity retention after 100 cycles at 0.2C.This work offers new insights into synthesizing high-entropy nanomaterials for improving the electrochemical performance of Li–S batteries.
基金financially support from the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA25040201)the National Natural Science Foundation of China(Grant No.51727901)support provided by the Deanship of Scientific Research(DSR)at King Fahd University of Petroleum&Minerals(KFUPM)(Grant No.DF201020)
文摘Tungsten has promising applications in high-radiation,high-erosion and high-impact environments.Laser peening is an effective method to enhance the surface mechanical properties of tungsten materials.However,the ultrafast dynamic mechanism of defect evolutions induced by laser shockwave in tungsten lattice is unclear.Here,we investigated the evolutions and interactions of various defects under ultrafast compressive process in tungsten lattice using molecular dynamic method.The results confirm the brittleness of tungsten and reveal that void can reduce the yield strain and strength of the tungsten lattice by accelerating defect mesh extension and promoting the dislocation nucleation around itself.Dislocation density is increased with compressive strain rate.Meanwhile,dislocation multiplication and motion reduce the elastic stage and play a dominant role during the plastic deformation of tungsten lattice.Additionally,void can disrupt the dislocation displacement and promote the pinning effect on dislocations by defect mesh extension.
基金This work was financially supported by the National Natural Science Foundation of China(21773133)Taishan Scholars Advantageous and Distinctive Discipline Program for supporting the research team of energy storage materials of Shandong Province,China.
文摘Less-expensive but efficient electrocatalysts are essential to accelerate the commercialization of fuel cells.Herein,ultrathin PdPb nanowires(PdPb NWs)with a diameter of around 3.5 nm were prepared by using a one-step hydrothermal method.The introduction of Pb in Pd-based bimetallic nanostructures produced high differences in the morphology from Pd nanoparticles(NPs)to various PdPb NWs.All the as-prepared PdPb NWs exhibited better electrocatalytic activity and durability than Pd NPs due to the synergistic effect.Especially,Pd65Pb35 possessed the highest current density of about 3460 mA mgPd^−1 for the ethanol electrooxidation which was around 6.3 times higher than commercial Pd/C.The high-performance of Pd65Pb35 is attributed to the defect-rich and stable nanowire structure with optimized surface atomic arrangement,as evidenced by high resolution transmission electron microscopy measurements and long-time treatment in an acidic media.The differences in the morphologies and electrocatalytic activities of PdPb NWs with varied Pb contents have also been discussed and analyzed.
