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Dynamic phase transition behavior of a LiMn_(0.5)Fe_(0.5)PO_(4) olivine cathode material for lithium-ion batteries revealed through in-situ X-ray techniques 被引量:3
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作者 Sujeera Pleuksachat Phongsit Krabao +6 位作者 Sarawut Pongha Viyada Harnchana Pawinee Klangtakai Wanwisa Limphirat Siriwat Soontaranon Jeffrey Nash Nonglak Meethong 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第8期452-459,I0012,共9页
LiMn_(0.5)Fe_(0.5)PO_(4) has attracted great interest due to its good electrochemical performance and higher operating voltages.This has led to a greater than 30 percent higher energy density than for commercial Li Fe... LiMn_(0.5)Fe_(0.5)PO_(4) has attracted great interest due to its good electrochemical performance and higher operating voltages.This has led to a greater than 30 percent higher energy density than for commercial Li Fe PO4 olivine cathodes.Understanding the phase transition behaviors and kinetics of this material will help researchers to design and develop next generation cathodes for Li-ion batteries.In this study,we investigated non-equilibrium phase transition behaviors in a LiMn_(0.5)Fe_(0.5)PO_(4) cathode material during charge–discharge processes by varying current rates(C-rates)using synchrotron in-situ X-ray techniques.These methods included wide angle X-ray scattering(in-situ WAXS)and X-ray absorption spectroscopy(in-situ XAS).The WAXS spectra indicate that the phase transition of LiMn_(0.5)Fe_(0.5)PO_(4) material at slow C-rates is induced by a two-phase reaction.In contrast,at a high C-rate(5 C),the formation of an intermediate phase upon discharge is clearly observed.Concurrently,the oxidation numbers of the redox reactions of Fe^(2+)/Fe^(3+)and Mn^(2+)/Mn^(3+)were evaluated using in-situ XAS.This combination of synchrotron in-situ X-ray techniques gives clear insights into the non-equilibrium phase transition behavior of a LiMn_(0.5)Fe_(0.5)PO_(4) cathode material.This new understanding will be useful for further developments of this highly promising cathode material for practical commercialization. 展开更多
关键词 LiMn_(0.5)Fe_(0.5)PO_(4) Phase transition in-situ x-ray techniques
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Anomalous bond lengthening in compressed magnetic doped semiconductor Ba(Zn_(0.95)Mn_(0.05))_(2)As_(2)
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作者 Fei Sun Yi Peng +3 位作者 Guoqiang Zhao Xiancheng Wang Zheng Deng Changqing Jin 《Journal of Semiconductors》 EI CAS CSCD 2024年第4期36-41,共6页
Applying pressure has been evidenced as an effective method to control the properties of semiconductors,owing to its capability to modify the band configuration around Fermi energy.Correspondingly,structural evolution... Applying pressure has been evidenced as an effective method to control the properties of semiconductors,owing to its capability to modify the band configuration around Fermi energy.Correspondingly,structural evolutions under external pres-sures are required to analyze the mechanisms.Herein high-pressure structure of a magnetic doped semiconductor Ba(Zn_(0.95)Mn_(0.05))_(2)As_(2)is studied with combination of in-situ synchrotron X-ray diffractions and diamond anvil cells.The materials become ferromagnetic with Curie temperature of 105 K after further 20%K doping.The title material undergoes an isostruc-tural phase transition at around 19 GPa.Below the transition pressure,it is remarkable to find lengthening of Zn/Mn-As bond within Zn/MnAs layers,since chemical bonds are generally shortened with applying pressures.Accompanied with the bond stretch,interlayer As-As distances become shorter and the As-As dimers form after the phase transition.With further compres-sion,Zn/Mn-As bond becomes shortened due to the recovery of isotropic compression on the Zn/MnAs layers. 展开更多
关键词 magnetic semiconductor high-pressure in-situ x-ray diffraction phase transition
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Novel high-voltage cathode for aqueous zinc ion batteries:Porous K_(0.5)VOPO_(4)·1.5H_(2)O with reversible solid-solution intercalation and conversion storage mechanism
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作者 Liyu Wang Mingliang Zhao +9 位作者 Xiaoyu Zhang Menghua Wu Yu Zong Yu Chen Xinliang Huang Mingjie Xing Xin Ning Wen Wen Daming Zhu Xiaochuan Ren 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第6期71-78,I0003,共9页
Cathode materials that possess high output voltage,as well as those that can be mass-produced using facile techniques,are crucial for the advancement of aqueous zinc-ion battery(ZIBs)applications,Herein,we present for... Cathode materials that possess high output voltage,as well as those that can be mass-produced using facile techniques,are crucial for the advancement of aqueous zinc-ion battery(ZIBs)applications,Herein,we present for the first time a new porous K_(0.5)VOPO_(4)·1.5H_(2)O polyanionic cathode(P-KIVP)with high output voltage(above 1.2 V)that can be manufactured at room temperature using straightforward coprecipitation and etching techniques.The P-KVP cathode experiences anisotropic crystal plane expansion via a sequential solid-solution intercalation and phase co nversion pathway throughout the Zn^(2+)storage process,as confirmed by in-situ synchrotron X-ray diffraction and ex-situ X-ray photoelectron spectroscopy.Similar to other layered vanadium-based polyanionic materials,the P-KVP cathode experiences a progressive decline in voltage during the cycle,which is demonstrated to be caused by the irreversible conversion into amorphous VO_(x).By introducing a new electrolyte containing Zn(OTF)_(2) to a mixed triethyl phosphate and water solution,it is possible to impede this irreversible conversion and obtain a high output voltage and longer cycle life by forming a P-rich cathode electrolyte interface layer.As a proof-of-concept,the flexible fiber-shaped ZIBs based on modified electrolyte woven into a fabric watch band can power an electronic watch,highlighting the application potential of P-KVP cathode. 展开更多
关键词 Aqueous zinc ion battery CATHODE Porous material High voltage platform in-situ synchrotron x-ray diffraction
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MAX phase forming mechanism of M-Al-C(M=Ti,V,Cr)coatings:In-situ X-ray diffraction and first-principle calculations
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作者 Jianghuai Yuan Zhenyu Wang +5 位作者 Guanshui Ma Xiaojing Bai Yong Li Xiaoying Cheng Peiling Ke Aiying Wang 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2023年第12期140-152,共13页
The interesting hybrid properties of ceramics and metals induced by unique nano-laminated structures make the M_(n+1)AX n(MAX)phase attractive as a potential protective coating for vital structural compo-nents in hars... The interesting hybrid properties of ceramics and metals induced by unique nano-laminated structures make the M_(n+1)AX n(MAX)phase attractive as a potential protective coating for vital structural compo-nents in harsh systems.However,an extremely narrow phase-forming region makes it difficult to prepare MAX phase coatings with high purity,which is required to obtain coatings with high-temperature anti-oxidation capabilities.This work describes the dependence of the phase evolution in deposited M-Al-C(M=Ti,V,Cr)coatings as a function on temperature using in-situ X-ray diffraction analysis.Compared to V_(2)AlC and Cr_(2)AlC MAX phase coatings,the Ti_(2)AlC coating displayed a higher phase-forming tempera-ture accompanied by a lack of any intermediate phases before the appearance of the Ti_(2)AlC MAX phase.The results of the first-principle calculations correlated with the experience in which Ti_(2)AlC exhibited the largest formation energy and density of states.The effect of the phase compositions of these three MAX phase coatings on mechanical properties were also investigated using ex-situ Vickers and nano-indenter tests,demonstrating the improved mechanical properties with good stability at high temperatures.These findings provide a deeper understanding of the phase-forming mechanism of MAX phase coatings to guide the preparation of high-purity MAX phase coatings and the optimization of MAX phase coatings with expected intermediate phases such as Cr_(2)C,V_(2)C etc.,as well as their application as protective coat-ings in temperature-related harsh environments. 展开更多
关键词 MAX phase coating Phase-formation mechanism in-situ x-ray diffraction First-principle calculations Mechanical properties
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Effect of N-doping-derived solvent adsorption on electrochemical double layer structure and performance of porous carbon
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作者 Zhe-Fan Wang Cheng Tang +6 位作者 Qian Sun Ya-Lu Han Zhi-Jian Wang Lijing Xie Shou-Chun Zhang Fang-Yuan Su Cheng-Meng Chen 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第5期120-127,I0004,共9页
N-doped porous carbon has been extensively investigated for broad electrochemical applications.The performance is significantly impacted by the electrochemical double layer(EDL),which is material dependent and hard to... N-doped porous carbon has been extensively investigated for broad electrochemical applications.The performance is significantly impacted by the electrochemical double layer(EDL),which is material dependent and hard to characterize.Limited understanding of doping-derived EDL structure hinders insight into the structure-performance relations and the rational design of high-performance materials.Thus,we analyzed the mass and chemical composition variation of EDL within electrochemical operation by electrochemical quartz crystal microbalance,in-situ X-ray photoelectron spectroscopy,and time-offlight secondary ion mass spectrometry.We found that N-doping triggers specifically adsorbed propylene carbonate solvent in the inner Helmholtz plane(IHP),which prevents ion rearrangement and enhances the migration of cations.However,this specific adsorption accelerated solvent decomposition,rendering rapid performance degradation in practical devices.This work reveals that the surface chemistry of electrodes can cause specific adsorption of solvents and change the EDL structure,which complements the classical EDL theory and provide guidance for practical applications. 展开更多
关键词 Carbon materials Electrochemical double layer Electrochemical quartz crystal microbalance in-situ x-ray photoelectron spectroscopy N-DOPING
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In-situ observation of solid-liquid interface transition during directional solidification of Al-Zn alloy via X-ray imaging 被引量:2
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作者 Yuanhao Dong Sansan Shuai +4 位作者 Tianxiang Zheng Jiawei Cao Chaoyue Chen Jiang Wang Zhongming Ren 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2020年第4期113-123,共11页
The morphological instability of solid/liquid(S/L)interface during solidification will result in different patterns of microstructure.In this study,two dimension(2 D)and three dimension(3 D)in-situ observation of soli... The morphological instability of solid/liquid(S/L)interface during solidification will result in different patterns of microstructure.In this study,two dimension(2 D)and three dimension(3 D)in-situ observation of solid/liquid interfacial morphology transition in Al-Zn alloy during directional solidification were performed via X-ray imaging.Under a condition of increasing temperature gradient(G),the interface transition from dendritic pattern to cellular pattern,and then to planar growth with perturbation was captured.The effect of solidification parameter(the ratio of temperature gradient and growth velocity(v),G/v)on morphological instabilities was investigated and the experimental results were compared to classical"constitutional supercooling"theory.The results indicate that 2 D and 3 D evolution process of S/L interface morphology under the same thermal condition are different.It seems that the S/L interface in 2 D observation is easier to achieve planar growth than that in 3 D,implying higher S/L interface stability in 2 D thin plate samples.This can be explained as the restricted liquid flow under 2 D solidification which is beneficial to S/L interface stability.The in-situ observation in present study can provide coherent dataset for microstructural formation investigation and related model validation during solidification. 展开更多
关键词 AL-ZN ALLOY Directional SOLIDIFICATION Solid/liquid interface INSTABILITY in-situ observation x-ray imaging
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Preparation, Characterization of Superacid SO_4^(2-)/ZrO_2-SiO_2 and Its Activity on Catalytic Synthesis of Methyl p-Nitrobenzoate 被引量:2
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作者 王刚 TAO Liya +5 位作者 HOU Xin CAO Hi DONG Cheng NIE Wo XU Jun 张立庆 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第5期895-899,共5页
Solid superacid SO42-/ZrO2-SiO2 was prepared by dip-impregnation method, and its catalytic activity was tested with esterification of p-nitrobenzoic acid and methanol. The optimum conditions were also found, that is, ... Solid superacid SO42-/ZrO2-SiO2 was prepared by dip-impregnation method, and its catalytic activity was tested with esterification of p-nitrobenzoic acid and methanol. The optimum conditions were also found, that is, the molar ratio between silica and zirconia was 10:1, the calcination temperature was 550 ℃ and the soaked consistency of H2SO4 was 1.0 mol.L-1. Under the conditions that the ratio of methanol to aeid(mL/ g) was 12:1, the amount of catalyst was 0.5 g, the reaction time was 5 h and the stirring speed was 800 r.min-1, the yield of methyl p-nitrobenzoate could reach up to 90.5%. Then the characterizations of cataslyst, including the acidity and types of acidic centers, specific surface area and surface structure was respectively examined by Hammer indicator, in-situ pyridine IR, BET method, FT-IR(KBr), transmission electron microscope (TEM), and X-ray diffraction (XRD). The results showed that the catalyst SO42-/ZrO2-SiO2 was superacid with high specific surface area due to Ho〈-12.70. It contained acidic sites of Lewis and BrФnsted, and its surface structure changed after esterification. The zirconia crystal was mainly tetragonal and silica crystal was not found. 展开更多
关键词 solid superacid methyl p-nitrobenzoate in-situ pyridine IR x-ray diffraction
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Plasma assisted synthesis of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2) cathode materials with good cyclic stability at subzero temperatures 被引量:2
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作者 Fanbo Meng Renzong Hu +3 位作者 Zhiwei Chen Liang Tan Xuexia Lan Bin Yuan 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第5期46-55,共10页
Layered Ni-rich cathode materials,LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622),are synthesized via solid reaction assisted with a plasma milling pretreatment,which is resulted in lowering sintering temperatures for solid p... Layered Ni-rich cathode materials,LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622),are synthesized via solid reaction assisted with a plasma milling pretreatment,which is resulted in lowering sintering temperatures for solid precursors.The plasma milling pretreated NCM622 cathode material sintered at 780℃(named as PM-780)demonstrates good cycling stability at both room and subzero temperatures.Specifically,the PM-780 cathode delivers an initial discharge capacity of 171.2 mAh g^(-1) and a high capacity retention of 99.7%after 300 cycles with current rate of 90 mA g^(-1) at 30℃,while stable capacities of 120.3 and 94.0 m Ah g^(-1) can be remained at-10℃and-20℃in propylene carbonate contained electrolyte,respectively.In-situ XRD together with XPS and SEM reveal that the NCM622 cycled at-10℃presented better structural stability and more intact interface than that of cathodes cycled at 30℃.It is also found that subzero temperatures only limit the discharge potential of NCM622 without destroying its structure during cycling since it still exhibits high discharge capacity at 30℃after cycled at subzero temperatures.This work may expand the knowledge about the low-temperature characteristics of layered cathode materials for Li-ion batteries and lay the foundation for its further applications. 展开更多
关键词 Ni-rich cathode materials Solid reaction Plasma milling Subzero temperature in-situ x-ray diffraction
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Impact of Annealing Treatment on the Behaviour of Titanium Dioxide Nanotube Layers 被引量:1
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作者 Marie Siampiringue Christophe Massard +3 位作者 Eric Caudron Yves Sibaud Mohammed Sarakha Komla Oscar Awitor 《Journal of Biomaterials and Nanobiotechnology》 2016年第3期142-153,共13页
In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs t... In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs to be better understood. Nanotube layers were prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution during 20 minutes and then annealed in air atmosphere. In-situ X-ray diffraction analysis, coupled with thermogravimetry, gives us an inside on the oxidation behaviour of titanium dioxide nanotube layers compared to bulk reference samples. Structural studies were performed at 700°C for 12 h in order to follow the time consequences on the oxidation of the material, in sufficient stability conditions. In-situ XRD brought to light that the amorphous oxide layer induced by anodization is responsible for the simultaneous growths of anatase and rutile phase during the first 30 minutes of annealing while the bulk sample oxidation leads to the nucleation of a small amount of anatase TiO<sub>2</sub>. The initial amorphous oxide layer created by anodization is also responsible for the delay in crystallization compared to the bulk sample. Thermogravimetric analysis exhibits parabolic shape of the mass gain for both anodized and bulk sample;this kinetics is caused by the formation of a rutile external protective layer, as depicted by the associated in-situ XRD diffractograms. We recorded that titanium dioxide nanotube layers exhibit a lower mean mass gain than the bulk, because of the presence of an initial amorphous oxide layer on anodized samples. In-situ XRD results also provide accurate information concerning the sub-layers behavior during the annealing treatment for the bulk and nanostructured layer. Anatase crystallites are mainly localized at the interface oxide layer-metal and the rutile is at the external interface. Sample surface topography was characterized using scanning electron microscopy (SEM). As a probe of the photoactivity of the annealed TiO<sub>2</sub> nanotube layers, degradation of an acid orange 7 (AO7) dye solution and 4-chlorophenol under UV irradiation (at 365 nm) were performed. Such titanium dioxide nanotube layers show an efficient photocatalytic activity and the analytical results confirm the degradation mechanism of the 4-chlorophenol reported elsewhere. 展开更多
关键词 Titanium Dioxide Nanotubes in-situ x-ray Diffraction Annealing Treatment PHOTO-DEGRADATION
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Modulation of lattice oxygen boosts the electrochemical activity and stability of Co-free Li-rich cathodes
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作者 Gui-Jing Xu Wang Ke +5 位作者 Fu-Da Yu Jie Feng Yun-Shan Jiang Lan-Fang Que Lei Zhao Zhen-Bo Wang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第12期117-126,I0004,共11页
Co-free Li-rich layered oxide cathodes have drawn much attention owing to their low cost and high energy density.Nevertheless,anion oxidation of oxygen leads to oxygen peroxidation during the first charging process,wh... Co-free Li-rich layered oxide cathodes have drawn much attention owing to their low cost and high energy density.Nevertheless,anion oxidation of oxygen leads to oxygen peroxidation during the first charging process,which leads to co-migration of transition metal ions and oxygen vacancies,causing structural instability.In this work,we propose a pre-activation strategy driven by chemical impregnation to modulate the chemical state of surface lattice oxygen,thus regulating the structural and electrochemical properties of the cathodes.In-situ X-ray diffraction confirms that materials based on activated oxygen configuration have higher structural stability.More importantly,this novel efficient strategy endows the cathodes having a lower surface charge transfer barrier and higher Li+transfer kinetics characteristic and ameliorates its inherent issues.The optimized cathode exhibits excellent electrochemical performance:after 300 cycles,high capacity(from 238 m Ah g^(-1)to 193 m Ah g^(-1)at 1 C)and low voltage attenuation(168 mV)are obtained.Overall,this modulated surface lattice oxygen strategy improves the electrochemical activity and structural stability,providing an innovative idea to obtain high-capacity Co-free Li-rich cathodes for next-generation Li-ion batteries. 展开更多
关键词 PRE-ACTIVATION Modulation of lattice oxygen in-situ x-ray diffraction Structure stability Co-free Li-rich cathodes
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The highly selective catalytic hydrogenation of CO_(2)to CO over transition metal nitrides
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作者 Yichao Wu Zhiwei Xie +6 位作者 Xiaofeng Gao Xian Zhou Yangzhi Xu Shurui Fan Siyu Yao Xiaonian Li Lili Lin 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2022年第3期248-254,共7页
Three transition metal-like facet centered cubic structured transition metal nitrides,γ-Mo_(2)N,β-W_(2)N andδ-NbN,are synthesized and applied in the reaction of CO_(2)hydrogenation to CO.Among the three nitride cat... Three transition metal-like facet centered cubic structured transition metal nitrides,γ-Mo_(2)N,β-W_(2)N andδ-NbN,are synthesized and applied in the reaction of CO_(2)hydrogenation to CO.Among the three nitride catalysts,theγ-Mo_(2)N exhibits superior activity to target product CO,which is 4.6 and 76 times higher than the other two counterparts ofβ-W_(2)N andδ-NbN at 600℃,respectively.Additionally,γ-Mo_(2)N exhibits excellent stability on both cyclic heating-cooling and high space velocity steady state operation.The deactivation degree of cyclic heating-cooling evaluation after 5 cycles and long-term stability performance at 773 and 873 K in 50 h are all less than 10%.In-situ XRD and kinetic studies suggest that theγ-Mo_(2)N itself is able to activate both of the reactants CO_(2)and H_(2).Below 400℃,the reaction mainly occurs at the surface ofγ-Mo_(2)N catalyst.CO_(2)and H_(2)competitively adsorbe on the surface of catalyst and CO_(2)is the relatively stronger surface adsorbate.At a higher temperature,the interstitial vacancies of theγ-Mo_(2)N can be reversibly filled with the oxygen from CO_(2)dissociation.Both of the surface and bulk phase sites ofγ-Mo_(2)N participate in the high temperature CO_(2)hydrogenation pathway. 展开更多
关键词 Carbon dioxide Chemical reaction CATALYSIS Reverse water gas shift(RWGS)reaction Transition metal nitride in-situ x-ray diffraction characterization
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Design of advanced porous silver powder with high-sintering activity to improve silicon solar cells
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作者 Yongsheng Li Ziwei Chen +11 位作者 Rui Zhou Wenguang Zhao Mu Li Jun Chen Zhongyuan Huang Jian Liu Yuhang Li Maolin Yang Minghan Yu Dong Zhou Yuan Lin Feng Pan 《Nano Research》 SCIE EI CSCD 2024年第4期3189-3197,共9页
Silver(Ag)paste is widely used in semiconductor metallization,especially in silicon solar cells.Ag powder is the material with the highest proportion in Ag paste.The morphology and structure of Ag powder are crucial w... Silver(Ag)paste is widely used in semiconductor metallization,especially in silicon solar cells.Ag powder is the material with the highest proportion in Ag paste.The morphology and structure of Ag powder are crucial which determine its characteristics,especially for the sintering activity.In this work,a simple method was developed to synthesize a type of microcrystalline spherical Ag particles(SP-A)with internal pores and the structural changes and sintering behavior were thoroughly studied by combining ultra-small-angle X-ray scattering(USAXS),small-angle X-ray scattering(SAXS),in-situ heating X-ray diffraction(XRD),focused ion beam(FIB),and thermal analysis measurement.Due to the unique internal pores,the grain size of SP-A is smaller,and the coefficient of thermal expansion(CTE)is higher than that of traditional solid Ag particles.As a result,the sintering activity of SP-A is excellent,which can form a denser sintered body and form silver nanoparticles at the Ag–Si interface to improve silver silicon contact.Polycrystalline silicon solar cell built with SP-A obtained a low series resistance(Rs)and a high photoelectric conversion efficiency(PCE)of 19.26%.These fill a gap in Ag particle structure research,which is significant for the development of high-performance electronic Ag particles and efficient semiconductor devices. 展开更多
关键词 silver particles small angle x-ray scattering(SAXS) pore size distribution in-situ heating x-ray diffraction(XRD) SINTERING silicon solar cells
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Revealing structure behavior behind the piezoelectric performance of prototype lead-free Bi_(0.5)Na_(0.5)TiO_(3)-BaTiO_(3) under in-situ electric field
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作者 Huajie Luo Shiyu Tang +7 位作者 Hui Liu Zheng Sun Baitao Gao Yang Ren He Qi Shiqing Deng Houbing Huang Jun Chen 《Journal of Materiomics》 SCIE 2022年第6期1104-1112,共9页
Bi_(0.5)Na_(0.5)TiO_(3)-BaTiO_(3)(BNT-100xBT)ceramics are promising candidates for piezoelectric applications.The correlation between their structure and piezoelectric properties has attracted considerable interest.He... Bi_(0.5)Na_(0.5)TiO_(3)-BaTiO_(3)(BNT-100xBT)ceramics are promising candidates for piezoelectric applications.The correlation between their structure and piezoelectric properties has attracted considerable interest.Herein,the structures of 6BT and 7BT with distinct piezoelectricity are investigated via in-situ synchrotron X-ray diffraction and transmission electron microscopy.It is found that although both compositions present morphotropic phase boundary(MPB)features with coexisting R3c and P4bm phases,their refined structures are significantly different.6BT is composed of the R3c phase with a small P4bm fraction after electrical poling,while 7BT presents comparable fractions of the two phases.Less pronounced structure distortion and oxygen octahedral tilting occur in 7BT,which favor the phase transformation,resulting in an enhanced piezoelectricity.This enhancement driven by structural flexibility is elucidated by phenomenological analysis.These results demonstrate that the design of high piezoelectricity at MPBs should consider not only the phase-coexisting states but also the refined crystal structure. 展开更多
关键词 in-situ synchrotron x-ray diffraction Piezoelectric properties Crystal structure
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Advanced TEM Characterization for Single-atom Catalysts:from Ex-situ Towards In-situ
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作者 WANG Guowei KE Xiaoxing SUI Manling 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2022年第5期1172-1184,共13页
Clean energy innovation has triggered the development of single-atom catalysts(SACs)due to their excellent catalytic activity,high tunability and low cost.The success of SACs for many catalytic reactions has opened a ... Clean energy innovation has triggered the development of single-atom catalysts(SACs)due to their excellent catalytic activity,high tunability and low cost.The success of SACs for many catalytic reactions has opened a new field,where the fundamentals of catalytic property-structure relationship at atomic level await exploration,and thus raises challenges for structural characterization.Among the characterization techniques for SACs,aberration-corrected transmission electron microscopy(TEM)has become an essential tool for direct visualization of single atoms.In this review,we briefly summarize recent studies on SACs using advanced TEM.We first introduce TEM methods,which are particularly important for SACs characterization,and then discuss the applications of advanced TEM for SAC characterization,where not only atomic dispersion of single atoms can be studied,but also the distribution of elements and the valence state with local coordination can be resolved.We further extend our review towards in-situ TEM,which has increasing importance for the fundamental understanding of catalytic mechanism.Perspectives of TEM for SACs are finally discussed. 展开更多
关键词 Single-atom catalyst Transmission electron microscopy(TEM) Scanning transmission electron microscopy(STEM) Electron energy loss spectroscopy(EELS) Energy dispersive x-ray spectroscopy(EDX) in-situ TEM
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Self-supported Ni6MnO8 3D mesoporous nanosheet arrays with ultrahigh lithium storage properties and conversion mechanism by in-situ XAFS
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作者 Dongdong Zhao Peng Yu +5 位作者 Lei Wang Fanfei Sun Li Zhao Chungui Tian Wei Zhou Honggang Fu 《Nano Research》 SCIE EI CAS CSCD 2017年第1期263-275,共13页
Murdochite-type Ni6MnO8 three-dimensional mesoporous nanosheet arrays grown on carbon cloth (NMO-SA/CC) are synthesized using an in-situ growth strategy. As self-supported binder-free anodes for LIBs, the NMO-SA/CC ... Murdochite-type Ni6MnO8 three-dimensional mesoporous nanosheet arrays grown on carbon cloth (NMO-SA/CC) are synthesized using an in-situ growth strategy. As self-supported binder-free anodes for LIBs, the NMO-SA/CC hierarchical nanostructures exhibit ultrahigh capacity, excellent cycling stability, and good rate capability. The excellent lithium storage performance can be ascribed to the perfect electrical contact between NMO-SA and CC. The mesopores in the thin nanosheet can maximize the electrode contact with the electrolyte by decreasing the Li+ diffusion path. Moreover, these effects relieve the pulverization and agglomeration that originate from the large volume variations during the Li+ intercalation/deintercalation cycles. The in-situ X-ray absorption fine structure (XAFS) spectrum recorded during the initial lithiation/delithiation processes reveals the conversion reaction process. 展开更多
关键词 Ni6MnO8 self-supported in-situ x-ray absorptionfine structure lithium-ion battery
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Rational synthesis of chitin-derived nitrogen-doped porous carbon nanofibers for efficient polysulfide confinement 被引量:1
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作者 Shanfeng Yang Shuiping Luo +3 位作者 Xinji Dong Li Tian Pei Kang Shen Jinliang Zhu 《Nano Research》 SCIE EI CSCD 2023年第6期8478-8487,共10页
Principles of inexpensive biotechnology are being increasingly used to address the problems posed by the use of lithium-sulfur batteries.We used chitin,a low-cost marine biowaste product,as a precursor for the in-situ... Principles of inexpensive biotechnology are being increasingly used to address the problems posed by the use of lithium-sulfur batteries.We used chitin,a low-cost marine biowaste product,as a precursor for the in-situ preparation of chitin-derived nitrogendoped hierarchical porous carbon fibers(CNHPCFs)containing abundant pores.These materials are characterized by varying morphologies and high specific surface areas and present a hierarchical porous structure.CNHPCFs adsorb polysulfides,exhibit good ionic conductivity,and can be potentially used to generate green energy.These properties help address the problems of volume expansion and slow transport.The CNHPCF-1@S cathode exhibits excellent cycling performance and high capacity(1368.80 mAh·g^(−1)at 0.2 C;decay rate:0.011%per turn at 5 C).The high electrochemical reversibility recorded for CNHPCF-1@S and the stepwise reaction mechanism followed were studied using the in-situ X-ray diffraction and in-situ Raman spectroscopy techniques.The results reported herein can potentially help develop new ideas for the recycling and treatment of marine biofertilizers.The results can also provide a platform to improve the application prospects of lithium-sulfur batteries. 展开更多
关键词 CHITIN carbon fiber Li-S battery in-situ Raman in-situ x-ray diffraction
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Interfacial engineering of SnO_(2)/Bi_(2)O_(2)CO_(3)heterojunction on heteroatoms-doped carbon for high-performance CO_(2)electroreduction to formate 被引量:1
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作者 Danni Wang Tingting Sun +8 位作者 Lianbin Xu Lei Gong Baotong Chen Pianpian Zhang Tianyu Zheng Qingmei Xu Houhe Pan Yuexing Zhang Jianzhuang Jiang 《Nano Research》 SCIE EI CSCD 2023年第2期2278-2285,共8页
Electrochemical CO_(2)reduction is a viable,economical,and sustainable method to transform atmospheric CO_(2)into carbon-based fuels and effectively reduce climate change and the energy crisis.Constructing robust cata... Electrochemical CO_(2)reduction is a viable,economical,and sustainable method to transform atmospheric CO_(2)into carbon-based fuels and effectively reduce climate change and the energy crisis.Constructing robust catalysts through interface engineering is significant for electrocatalytic CO_(2)reduction(ECR)but remains a grand challenge.Herein,SnO2/Bi_(2)O_(2)CO_(3)heterojunction on N,S-codoped-carbon(SnO_(2)/BOC@NSC)with efficient ECR performance was firstly constructed by a facile synthetic strategy.When the SnO_(2)/BOC@NSC was utilized in ECR,it exhibits a large formic acid(HCOOH)partial current density(JHCOOH)of 86.7 mA·cm^(−2)at−1.2 V versus reversible hydrogen electrode(RHE)and maximum Faradaic efficiency(FE)of HCOOH(90.75%at−1.2 V versus RHE),respectively.Notably,the FEHCOOH of SnO_(2)/BOC@NSC is higher than 90%in the flow cell and the JHCOOH of SnO_(2)/BOC@NSC can achieve 200 mA·cm^(−2)at−0.8 V versus RHE to meet the requirements of industrialization level.The comparative experimental analysis and in-situ X-ray absorption fine structure reveal that the excellent ECR performance can be ascribed to the synergistic effect of SnO_(2)/BOC heterojunction,which enhances the activation of CO_(2)molecules and improves electron transfer.This work provides an efficient SnO_(2)-based heterojunction catalyst for effective formate production and offers a novel approach for the construction of new types of metal oxide heterostructures for other catalytic applications. 展开更多
关键词 HETEROJUNCTION charge transfer electrochemical CO_(2)reduction flow cell in-situ x-ray absorption fine structure
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Pd-Ni-P非晶合金多形性转变的成分依赖性
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作者 杜清 刘雄军 +6 位作者 曹一欢 曾桥石 王辉 吴渊 蒋虽合 张晓宾 吕昭平 《Science China Materials》 SCIE EI CAS CSCD 2023年第11期4189-4196,共8页
非晶合金复杂的化学成分特征为理解多形性转变带来了巨大挑战.在本文中,我们系统研究了(PdNi)_(100−x)P_(x)(15 at%<x<21 at%)非晶合金中加热诱导多形性转变的化学成分依赖性.差热分析与结构因子的演化规律表明重入型玻璃转变会随... 非晶合金复杂的化学成分特征为理解多形性转变带来了巨大挑战.在本文中,我们系统研究了(PdNi)_(100−x)P_(x)(15 at%<x<21 at%)非晶合金中加热诱导多形性转变的化学成分依赖性.差热分析与结构因子的演化规律表明重入型玻璃转变会随着P含量的增加(不超过17 at%)而逐渐被抑制,扩展X射线吸收精细结构分析拟合后的结构参数与原位升温同步辐射结果显示重入型玻璃转变的成分依赖性来源于金属–类金属键对(即Pd/Ni–P对)的成键能力差异以及由此导致的短程至中程有序化转变.这种成分依赖性可以导致重入型液-液转变和玻璃转变在Pd_(41.5)Ni_(41.5)P_(17)非晶合金中均可发生.本研究有助于加深对重入型玻璃转变原子机制的认识,同时澄清了对于Pd–Ni–P非晶合金体系中多形性转变结构起源的困惑. 展开更多
关键词 metallic glass compositional dependence glass transition in-situ synchrotron x-ray scattering extended x-ray absorption fine structure
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Grain boundary boosting the thermal stability of Pt/CeO_(2)thin films
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作者 Luyao Wang Xiaobao Li +10 位作者 Xiangchen Hu Shuyue Chen Zhehao Qiu Yifan Wang Hui Zhang Yi Yu Bo Yang Yong Yang Pasquale Orgiani Carmela Aruta Nan Yang 《Nano Research》 SCIE EI CSCD 2023年第2期3278-3286,共9页
Understanding how defect chemistry of oxide material influences the thermal stability of noble metal dopant ions plays an important role in designing high-performance heterogeneous catalytic systems.Here we use in-sit... Understanding how defect chemistry of oxide material influences the thermal stability of noble metal dopant ions plays an important role in designing high-performance heterogeneous catalytic systems.Here we use in-situ ambient-pressure X-ray photoemission spectroscopy(APXPS)to experimentally determine the role of grain boundary in the thermal stability of platinum doped cerium oxide(Pt/CeO_(2)).The grain boundaries were introduced in Pt/CeO_(2)thin films by pulsed laser deposition without significantly change of the surface microstructure.The defect level was tuned by the strain field obtained using a highly/low mismatched substrate.The Pt/CeO_(2)thin film models having well defined crystallographic properties but different grain boundary structural defect levels provide an ideal platform for exploring the evolution of Pt–O–Ce bond with changing the temperature in reducing conditions.We have direct demonstration and explanation of the role of Ce^(3+)induced by grain boundaries in enhancing Pt2+stability.We observe that the Pt^(2+)–O–Ce^(3+)bond provides an ideal coordinated site for anchoring of Pt^(2+)ions and limits the further formation of oxygen vacancies during the reduction with H_(2).Our findings demonstrate the importance of grain boundary in the atomic-scale design of thermally stable catalytic active sites. 展开更多
关键词 platinum doped cerium oxide(Pt/CeO_(2)) pulsed laser deposition epitaxial thin films grain boundaries defect engineering in-situ ambient-pressure x-ray photoemission spectroscopy
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Advances in Microscale Laser Shock Peening 被引量:2
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作者 KYSAR Jeffrey W. YAO Y.Lawrence 《Tsinghua Science and Technology》 SCIE EI CAS 2004年第5期506-518,共13页
The response of materials after microscale laser shock peening (μLSP) was experimentally characterized and compared with the theoretical prediction from the finite element method (FEM) analysis in microlength level... The response of materials after microscale laser shock peening (μLSP) was experimentally characterized and compared with the theoretical prediction from the finite element method (FEM) analysis in microlength level. X-ray micro-diffraction technique was applied to the post-peened single crystal aluminum of (001) and (110) orientations, and X-ray profile was analyzed by sub-profiling and Fourier analysis method. Spatially resolved residual stress and strain deviation was quantified and explained in terms of the hetero- geneous dislocation cell structure. In-plane crystal lattice rotation induced by μLSP was measured by elec- tron backscatter diffraction (EBSD) and compared with the FEM simulation. Average mosaic size was evaluated from X-ray profile Fourier analysis and compared with the result from EBSD. Surface strength in- crease and dislocation cell structure formation were studied. The systematical characterization will lay the ground work for better understanding the effect of μLSP in microlength level and developing more realistic simulations. 展开更多
关键词 laser shock peening x-ray micro-diffraction single crystal
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