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Slight Structural Disorder in Bithiophene-based Random Terpolymers with Improved Power Conversion Efficiency for Polymer Solar Cells 被引量:3
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作者 Meng-Han Wang Zhong-Yuan Xue +6 位作者 Zhi-Wei Wang Wei-Hua Ning Yu Zhong Ya-Nan Liu Chun-Feng Zhang Sven Huettner You-Tian Tao 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2018年第10期1129-1138,共10页
A series of random terpolymers P2-P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol% and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor ... A series of random terpolymers P2-P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol% and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor (D-A) type copolymer PTBT-Th (P1). All polymers showed similar molecular weight with number-average molecular weight (Mn) and weight-average molecular weight (Mw) in the range of (59-74) and (93-114) kg·mol-1, respectively, to ensure a fair comparison on the structure-property relationships. Compared with the control copolymer PTBT-Th, the random terpolymers exhibited enhanced absorption intensity in a wide range from 400 nm to 650 nm in both solution and film as well as in polymer/PC71BM blends. From grazing incident wide-angle X-ray diffraction (GIWAXS), compared with the regularly alternated copolymer PTB7-Th, the random terpolymers demonstrated mild structural disorder with reduced (100) lamellar stacking and slightly weakened (010) π-π stacking for the polymers as well as slightly reduced PC71BM aggregation in polymer/PC71BM blends. However, the measured hole mobility for terpolymers ((1.20-3.73) × 10 -4 cm2·V-1·s-1) was evaluated to be comparable or even higher than 1.35 × 10 -4 cm2·V-1 ·s-1 of the alternative copolymer. Enhanced average power conversion efficiency (PCE) from 7.35% to 8.11% and 7.79% to 8.37% was observed in both conventional and inverted device architectures from copolymer P1 to terpolymers P4, while further increasing the 2,2-bithiophene feed ratio decreased the PCE. 展开更多
关键词 Bithiophene-based random terpolymers structural disorder Polymer solar cells Photovoltaic properties
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Impact of Structural Disorder on Excitonic Behaviors and Dynamics in 2D Organic-Inorganic Hybrid Perovskites
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作者 Xiao-xia Li Shen-long Jiang Qun Zhang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2020年第5期561-568,I0006,I0007,I0078,共11页
Two thin-film 2 D organic-inorganic hybrid perovskites,i.e.,2-phenylethylammonium lead iodide(PEPI)and 4-phenyl-1-butylammonium lead iodide(PBPI)were synthesized and investigated by steady-state absorption,temperature... Two thin-film 2 D organic-inorganic hybrid perovskites,i.e.,2-phenylethylammonium lead iodide(PEPI)and 4-phenyl-1-butylammonium lead iodide(PBPI)were synthesized and investigated by steady-state absorption,temperature-dependent photoluminescence,and temperature-dependent ultrafast transient absorption spectroscopy.PBPI has a longer organic chain(via introducing extra ethyl groups)than PEPI,thus its inorganic skeleton can be distorted,bringing on structural disorder.The comparative analyses of spectral profiles and temporal dynamics revealed that the greater structural disorder in PBPI results in more defect states serving as trap states to promote exciton dynamics.In addition,the fine-structuring of excitonic resonances was unveiled by temperature-dependent ultrafast spectroscopy,suggesting its correlation with inorganic skeleton rather than organic chain.Moreover,the photoexcited coherent phonons were observed in both PEPI and PBPI,pointing to a subtle impact of structural disorder on the low-frequency Raman-active vibrations of inorganic skeleton.This work provides valuable insights into the optical properties,excitonic behaviors and dynamics,as well as coherent phonon effects in 2 D hybrid perovskites. 展开更多
关键词 2D hybrid perovskites structural disorder Exciton dynamics Excitonic resonances Coherent phonons PHOTOLUMINESCENCE Ultrafast spectroscopy
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Regulating Anderson localization with structural defect disorder
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作者 Mouyang Cheng Haoxiang Chen Ji Chen 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第10期102-107,共6页
Localization due to disorder has been one of the most intriguing theoretical concepts that evolved in condensed matter physics.Here,we expand the theory of localization by considering two types of disorders at the sam... Localization due to disorder has been one of the most intriguing theoretical concepts that evolved in condensed matter physics.Here,we expand the theory of localization by considering two types of disorders at the same time,namely,the original Anderson’s disorder and the structural defect disorder,which has been suggested to be a key component in recently discovered two-dimensional amorphous materials.While increasing the degree of both disorders could induce localization of wavefunction in real space,we find that a small degree of structural defect disorder can significantly enhance the localization.As the degree of structural defect disorder increases,localized states quickly appear within the extended phase to enter a broad crossover region with mixed phases.We establish two-dimensional diagrams for the wavefunction localization and conductivity to highlight the interplay between the two types of disorders.Our theoretical model provides a comprehensive understanding of localization in two-dimensional amorphous materials and highlights the promising tunability of their transport properties. 展开更多
关键词 Anderson localization structural defect disorder electronic transport properties
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Bismuth-based halide double perovskite Cs_(2)KBiCl_(6): Disorder and luminescence
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作者 Pan Liu Yanming Sun +6 位作者 Alberto J.Fernández-Carrión Bowen Zhang Hui Fu Lunhua He Xing Ming Congling Yin Xiaojun Kuang 《Chinese Chemical Letters》 SCIE CAS CSCD 2024年第5期504-508,共5页
A new bismuth-based halide double perovskite Cs_(2)KBiCl_(6) was isolated successfully through solid-state reactions and investigated using X-ray and neutron diffraction.Rather than an ordered structure,the crystal st... A new bismuth-based halide double perovskite Cs_(2)KBiCl_(6) was isolated successfully through solid-state reactions and investigated using X-ray and neutron diffraction.Rather than an ordered structure,the crystal structure consists of shifted Cs,K,Bi,and Cl sites from the ideal positions with fractional occupancy in compensation,leading to variable local coordination of Cs^(+)ions,as revealed by^(133)Cs solid-state nuclear magnetic resonance spectroscopy.Cs_(2)KBiCl_(6) displays volume hysteresis at 5-298 K range upon heating and cooling.The Cs_(2)KBiCl_(6) has a direct bandgap of 3.35(2)eV and red-shift luminescence of around 600 nm upon Mn doping compared with the Na analogue.The stabilization of disordered structure in Cs_(2)KBiCl_(6) is related to two factors including the large-sized K^(+)cation which prefers to coordinate with more than six Cl^(-),and the Bi^(3+)with 6s^(2) lone pair which has a preference for a local asymmetric environment.These findings could have general application and help to understand the structure and property of halide perovskites. 展开更多
关键词 Halide perovskite Double perovskite LUMINESCENCE disordered structure Direct bandgap
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Disordered Structure and Reversible Phase Transformation from K-Birnessite to Zn-Buserite Enable High-Performance Aqueous Zinc-lon Batteries
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作者 Nibagani Naresh Suyoon Eom +4 位作者 Sang Jun Lee Su Hwan Jeong Ji-Won Jung Young Hwa Jung Joo-Hyung Kim 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2024年第3期100-111,共12页
The layeredδ-MnO_(2)(dMO)is an excellent cathode material for rechargeable aqueous zinc-ion batteries owing to its large interlayer distance(~0.7 nm),high capacity,and low cost;however,such cathodes suffer from struc... The layeredδ-MnO_(2)(dMO)is an excellent cathode material for rechargeable aqueous zinc-ion batteries owing to its large interlayer distance(~0.7 nm),high capacity,and low cost;however,such cathodes suffer from structural degradation during the long-term cycling process,leading to capacity fading.In this study,a Co-doped dMO composite with reduced graphene oxide(GC-dMO)is developed using a simple cost-effective hydrothermal method.The degree of disorderness increases owing to the hetero-atom doping and graphene oxide composites.It is demonstrated that layered dMO and GC-dMO undergo a structural transition from K-birnessite to the Zn-buserite phase upon the first discharge,which enhances the intercalation of Zn^(2+)ions,H_(2)O molecules in the layered structure.The GC-dMO cathode exhibits an excellent capacity of 302 mAh g^(-1)at a current density of 100 mAg^(-1)after 100 cycles as compared with the dMO cathode(159 mAhg^(-1)).The excellent electrochemical performance of the GC-dMO cathode owing to Co-doping and graphene oxide sheets enhances the interlayer gap and disorderness,and maintains structural stability,which facilitates the easy reverse intercalation and de-intercalation of Zn^(2+)ions and H_(2)O molecules.Therefore,GC-dMO is a promising cathode material for large-scale aqueous ZIBs. 展开更多
关键词 aqueous zinc-ion batteries BIRNESSITE buserite disordered structure phase transformation
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Coupling macro-strain and micro-strain for high-performance PtCo fuel cell catalysts
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作者 Xiaomei Wu Zhanyong Xu +11 位作者 Fujun Lan Yuxin Liu Xinlong Wang Hao Wang Le Wei Guowei Wang Chaowei Wang Ge Chen Yingjun Sun Qiaoshi Zeng Manling Sui Xiaoxing Ke 《Journal of Energy Chemistry》 2025年第8期713-721,共9页
Limited by the sluggish kinetics at the cathode of proton exchange membrane fuel cells(PEMFCs),optimizing platinum-based alloy catalysts for oxygen reduction reaction remains a key target toward industrialization.Stra... Limited by the sluggish kinetics at the cathode of proton exchange membrane fuel cells(PEMFCs),optimizing platinum-based alloy catalysts for oxygen reduction reaction remains a key target toward industrialization.Strain engineering is widely employed to tune Pt-M catalysts,but its impact on the structure-property relationship is often interwoven with multiple factors.In this work,we propose a bi-stage strain tuning method and demonstrate it on the most common PtCo catalysts.Macro-strain is introduced by synthesizing single-crystal PtCo nanodendrites,whereas mild acid etching introduces micro-strain to the surface.The half-wave potential of as-treated catalysts reaches 0.959 V,and mass activity is up to 0.69 A mg^(−1)_(Pt).A minimal decrease of 2 mV is observed for half-wave potential after 10,000 cycles.Detailed analysis using advanced transmission electron microscopy,wide-angle X-ray scattering,etc.provides direct evidence that surface disorder at the atomic scale accounts for the enhanced activity and stability.In contrast,the simplicity of this approach allows for scaling up on Pt-M catalysts,as demonstrated on PEMFCs.The bi-stage strain tuning strategy provides a new perspective and reference for improving the activity and durability of Pt-M catalysts. 展开更多
关键词 Oxygen reduction reaction PtCo catalysts Identical-location transmission electron MICROSCOPY structural disorder Chemical etching
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Effect of sodium content on the electrochemical performance of P2-Na_(2)Ni_(2)TeO_(6)layered oxide cathode for sodium-ion batteries
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作者 Iqra Moeez Ali Hussain Umar Bhatti +4 位作者 Min-Kyung Cho Dieky Susanto Muhammad Akbar Ghulam Ali Kyung Yoon Chung 《Carbon Energy》 2025年第2期109-120,共12页
Sodium-ion batteries(SIBs)employ P2-type layered transition metal oxides as promising cathode materials,primarily due to their abundant natural reserves and environmentally friendly characteristics.However,structural ... Sodium-ion batteries(SIBs)employ P2-type layered transition metal oxides as promising cathode materials,primarily due to their abundant natural reserves and environmentally friendly characteristics.However,structural instability and complex phase transitions during electrochemical cycling pose significant challenges to their practical applications.Employing cation substitution serves as a straightforward yet effective strategy for stabilizing the structure and improving the kinetics of the active material.In this study,we introduce a Ni-rich honeycomb-layered Na_(2+x)Ni_(2)TeO_(6)(NNTO)cathode material with variable sodium content(x=0,0.03,0.05,0.10).Physicochemical characterizations reveal that excess sodium content at the atomic scale modifies the surface and suppresses phase transitions,while preserving the crystal structure.This results in enhanced cyclic performance and improved electrochemical kinetics at room temperature.Furthermore,we investigate the performance of the NNTO cathode material containing 10%excess sodium at a relatively high temperature of 60℃,where it exhibits 71.6%capacity retention compared to 60%for the pristine.Overall,our results confirm that a preconstructed surface layer(induced by excess sodium)effectively safeguards the Ni-based cathode material from surface degradation and phase transitions during the electrochemical processes,thus exhibiting superior capacity retention relative to the pristine NNTO cathode.This study of the correlation between structure and performance can potentially be applied to the commercialization of SIBs. 展开更多
关键词 honeycomb structure layered oxides sodium content sodium-ion battery structure disorder
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The effect of chemical ordering and coherent nanoprecipitates on bubble evolution in binary-phase vanadium alloys after He ion irradiation
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作者 Xing Liu Liyu Hao +7 位作者 Shangkun Shen Shiwei Wang Jian Zhang Kunjie Yang Tongde Shen Jin Li Zefeng Wu Engang Fu 《Journal of Materials Science & Technology》 2025年第9期312-320,共9页
This study reports the response of helium(He)ion irradiation on binary-phase structured alloy V_(34)Ti_(25)Cr_(10)Ni_(30)Pd1.The alloy consists of a VCr matrix with nano-sized TiNi precipitates and a B2 TiNi matrix wi... This study reports the response of helium(He)ion irradiation on binary-phase structured alloy V_(34)Ti_(25)Cr_(10)Ni_(30)Pd1.The alloy consists of a VCr matrix with nano-sized TiNi precipitates and a B2 TiNi matrix with nano-sized VCr precipitates.VCr is chemical-disordered and TiNi has a B2-ordered structure.The alloy was subjected to 400 keV He ion irradiation with a fluence of 1×10^(17)ions cm^(−2)at 450℃.The results show He bubbles within the chemical-disordered VCr matrix exhibit a near-spherical shape with a smaller size and higher density compared to that in chemical-ordered TiNi phase with a larger size,lower density,and faceted shape.This indicates the chemical-disordered VCr phase effectively suppresses He accumulation compared to the B2-ordered TiNi phase,emphasizing the dominance of chemical struc-tures in He bubble formation.The calculation of density functional theory(DFT)shows that Ti and Ni have lower vacancy formation energy than that of V and Cr,respectively,which results in the increased vacancy production in TiNi.Consequently,He bubbles in TiNi have a larger bubble size consistent with experimental observations of radiation-induced Ni segregation.These findings elucidate the roles of or-dered and disordered chemical structures in He bubble evolution,offering insights for the development of gas ion irradiation-resistant materials. 展开更多
关键词 Multicomponent alloy He bubble disordered chemical structures Nanoprecipitates
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Engineered high-density carbon defects enable accelerated sulfur conversion for kinetics-boosted room-temperature sodium-sulfur batteries
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作者 Kejian Tang Yingxinjie Wang +6 位作者 Xiangqi Peng Ziying Zhang Guohao Li Jie Wang Chi Chen Zhenjun Wu Xiuqiang Xie 《Journal of Energy Chemistry》 2025年第5期442-451,共10页
The practical application of room-temperature sodium-sulfur(RT Na-S)batteries is hindered by sluggish reaction kinetics and deleterious side reactions.To address these challenges,a defective carbon is designed as a su... The practical application of room-temperature sodium-sulfur(RT Na-S)batteries is hindered by sluggish reaction kinetics and deleterious side reactions.To address these challenges,a defective carbon is designed as a sulfur host through a simple temperature-controlled method.The abundant porosity and surface roughness enhance sulfur encapsulation and mitigate side reactions.Prominently,highly disordered structure facilitates the chemical adsorption towards NaPSs and accelerates sulfur conversion.Furthermore,electrochemical characterizations reveal that concentration polarization during the formation of long-chain NaPSs emerges as the key polarization and activation polarization dominates the nucleation of Na_(2)S during discharge,while they both significantly affect the formation of S_(8)/long-chain NaPSs during charge.Owing to the improved adsorption capability and electrocalatytic sites,S/CZ-900presents lower concentration polarization and activation polarization during both discharge and charge.Consequently,S/CZ-900 cathode achieves 1031,914,and 671 mAh g^(-1)at 1,2,and 5 C.The cathode with a high sulfur loading of 6.4 mg cm^(-2)delivers an impressive areal capacity of 14.3 mAh cm^(-2).Moreover,the S/CZ-900||Na/CZ-900(Al)full cell exhibits robust cycling stability,maintaining 1094 mAh g^(-1)after 40 cycles at 0.1 C.The insights provide a workable solution of metal-free carbonaceous host materials for the evolution of RT Na-S batteries. 展开更多
关键词 Metal-free carbonaceous sulfur host Highly disordered structure Porous and rough carbon RT Na-S batteries
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Wave localization in randomly disordered periodic layered piezoelectric structures 被引量:11
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作者 Fengming Li Yuesheng Wang +1 位作者 Chao Hu Wenhu Huang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2006年第6期559-567,共9页
Considering the mechnoelectrical coupling, the localization of SH-waves in disordered periodic layered piezoelectric structures is studied. The waves propagating in directions normal and tangential to the layers are c... Considering the mechnoelectrical coupling, the localization of SH-waves in disordered periodic layered piezoelectric structures is studied. The waves propagating in directions normal and tangential to the layers are considered. The transfer matrices between two consecutive unit cells are obtained according to the continuity conditions. The expressions of localization factor and localization length in the disordered periodic structures are presented. For the disordered periodic piezoelectric structures, the numerical results of localization factor and localization length are presented and discussed. It can be seen from the results that the frequency passbands and stopbands appear for the ordered periodic structures and the wave localization phenomenon occurs in the disordered periodic ones, and the larger the coefficient of variation is, the greater the degree of wave localization is. The widths of stopbands in the ordered periodic structures are very narrow when the properties of the consecutive piezoelectric materials are similar and the intervals of stopbands become broader when a certain material parameter has large changes. For the wave propagating in the direction normal to the layers the localization length has less dependence on the frequency, but for the wave propagating in the direction tangential to the layers the localization length is strongly dependent on the frequency. 展开更多
关键词 disordered periodic layered piezoelectric structures Transfer matrix Lyapunov exponent Localization factor Localization length
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Influences of Structure Disorder and Temperature on Properties of Proton Conductivity in Hydrogen-Bond Molecular Systems 被引量:1
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作者 PANG Xiao-Feng YU Jia-Feng 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第2期235-243,共9页
The dynamic properties of proton conductivity along hydrogen-bonded molecular systems, for example, ice crystal, with structure disorder or damping and finite temperatures exposed in an externally applied electric-fie... The dynamic properties of proton conductivity along hydrogen-bonded molecular systems, for example, ice crystal, with structure disorder or damping and finite temperatures exposed in an externally applied electric-field have been numerically studied by Runge-Kutta way in our soliton model. The results obtained show that the proton-soliton is very robust against the structure disorder including the fluctuation of the force constant and disorder in the sequence of masses and thermal perturbation and damping of medium, the velocity of its conductivity increases with increasing of the externally applied electric-field and decreasing of the damping coefficient of medium, but the proton-soliton disperses for quite great fluctuation of the "force constant and damping coefficient. In the numerical simulation we find that the proton-soliton in our model is thermally stable in a large region of temperature of T ≤ 273 K under influences of damping and externally applied electric-field in ice crvstal. This shows that our model is available and appropriate to ice. 展开更多
关键词 proton conductivity structure disorder temperature hydrogen bonded system
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Klein Paradox and Disorder-Induced Delocalization of Dirac Quasiparticles in One-Dimensional Systems 被引量:1
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作者 袁建辉 成泽 +2 位作者 尹淼 曾其军 张俊佩 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第12期1129-1133,共5页
Dirac particle penetration is studied theoretically with Dirac equation in one-dimensional systems. We investigate a one-dimensional system with N barriers where both barrier height and well width are constants random... Dirac particle penetration is studied theoretically with Dirac equation in one-dimensional systems. We investigate a one-dimensional system with N barriers where both barrier height and well width are constants randomly distributed in certain range. The one-parameter scaling theory for nonrelatiyistic particles is still valid for massive Dirac particles. In the same disorder sample, we find that the localization length of relativistic particles is always larger than that of nonrelativistic particles and the transmission coefficient related to incident particle in both cases fits the form T~ exp(-αL). More interesting, massless relativistic particles are entirely delocalized no matter how big the energy of incident particles is. 展开更多
关键词 Anderson localization disordered structures quantum transport localized states
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First-principles investigation of B2 partial disordered structure,martensitic transformation, elastic and magnetic properties of all-d-metal Ni-Mn-Ti Heusler alloys 被引量:1
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作者 Ziqi Guan Jing Bai +5 位作者 Jianglong Gu Xinzeng Liang Die Liu Xinjun Jiang Xiang Zhao Liang Zuo 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2021年第9期103-111,共9页
In this work,the B2 partial disordered structure of the austenitic parent phase,martensitic transformation,elastic and magnetic properties of the Ni8 Mn4+xTi4-x(x=0,1 and 2) Heusler alloys have been systematically inv... In this work,the B2 partial disordered structure of the austenitic parent phase,martensitic transformation,elastic and magnetic properties of the Ni8 Mn4+xTi4-x(x=0,1 and 2) Heusler alloys have been systematically investigated by the first-principles calculations.The preferential atomic occupation of B2 structure is one Ti atom exchange with the nearest neighboring Mn atom from the view of lowest energy principle.This disordered exchange sites(Mn-Ti) and the excess Mn atoms occupying the Ti sites(MnTi)could reduce the nearest Mn-Mn distance,resulting in the anti ferromagnetic state in the austenitic and martensitic phases of the alloys.The total magnetic moment of the alloy decreases with the increasing Mn content;it is ascribed to the antiferromagnetic magnetic moments of the excess Mn atoms.When x=0,the alloy does not undergo martensitic transformation since the austenite has absolute phase stability.The martensitic transformation will occur during cooling process for x=1 or 2,owing to the energy difference between the austenite and the martensite could provide the driving force for the phase transformation.The elastic properties of the cubic austenitic phase for the Ni2 MnTi alloy is calculated,and the results reveal the reason why Ni-Mn-Ti alloy has excellent mechanical properties.The origin of martensitic transformation and magnetic properties was discussed based on the electronic density of states. 展开更多
关键词 Ni-Mn-Ti First-principles calculations Martensitic transformation B2 partial disordered structure Elastic properties
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Candidate Biomarkers in Children with Autism Spectrum Disorder: A Review of MRI Studies 被引量:7
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作者 Dongyun Li Hans-Otto Karnath Xiu Xu 《Neuroscience Bulletin》 SCIE CAS CSCD 2017年第2期219-237,共19页
Searching for effective biomarkers is one of the most challenging tasks in the research ?eld of Autism Spectrum Disorder(ASD). Magnetic resonance imaging(MRI) provides a non-invasive and powerful tool for investi... Searching for effective biomarkers is one of the most challenging tasks in the research ?eld of Autism Spectrum Disorder(ASD). Magnetic resonance imaging(MRI) provides a non-invasive and powerful tool for investigating changes in the structure, function, maturation,connectivity, and metabolism of the brain of children with ASD. Here, we review the more recent MRI studies in young children with ASD, aiming to provide candidate biomarkers for the diagnosis of childhood ASD. The review covers structural imaging methods, diffusion tensor imaging, resting-state functional MRI, and magnetic resonance spectroscopy. Future advances in neuroimaging techniques, as well as cross-disciplinary studies and largescale collaborations will be needed for an integrated approach linking neuroimaging, genetics, and phenotypic data to allow the discovery of new, effective biomarkers. 展开更多
关键词 Autism spectrum disorder Biomarker Neuroimaging structural MRI Diffusion tensor imaging Resting-state functional MRI Magnetic resonance spectroscopy Children Human
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First-principles study of structural, elastic, and thermodynamic properties of ZrHf alloy
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作者 韦昭 翟东 +2 位作者 邵晓红 鲁勇 张平 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第4期111-116,共6页
Structural parameters, elastic constants, and thermodynamic properties of ordered and disordered solid solutions of ZrHf alloys are investigated through first-principles calculations based on density-functional theory... Structural parameters, elastic constants, and thermodynamic properties of ordered and disordered solid solutions of ZrHf alloys are investigated through first-principles calculations based on density-functional theory (DFF). The special quasi-random structure (SQS) method is used to model the disordered phase as a single unit cell, and two lamella structures are generated to model the ordered alloys. Small strains are applied to the unit cells to measure the elastic behavior and mechanical stability of ZrHf alloys and to obtain the independent elastic constants by the stress-strain relationship. Phonon dispersions and phonon density of states are presented to verify the thermodynamic stability of the considered phases. Our results show that both the ordered and disordered phases of ZrHf alloys are structurally stable. Based on the obtained phonon frequencies, thermodynamic properties, including Gibbs free energy, entropy, and heat capacity, are predicted within the quasi-harmonic approximation. It is verified that there are no obvious differences in energy between ordered and disordered phases over a wide temperature range. 展开更多
关键词 first-principles calculations ZrHf alloys disordered structure special quasi-random structure thermodynamic properties
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First-principles calculations of structural and electronic properties of Tl_xGa_(1-x)As alloys
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作者 G. Bilgec akyüz A. Y. Tunali +1 位作者 S. E. Gulebaglan N. B. Yurdasan 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第2期377-383,共7页
The zincblende ternary alloys Tl_xGa_(1-x) As(0 〈 x 〈 1) are studied by numerical analysis based on the plane wave pseudopotential method within the density functional theory and the local density approximation.... The zincblende ternary alloys Tl_xGa_(1-x) As(0 〈 x 〈 1) are studied by numerical analysis based on the plane wave pseudopotential method within the density functional theory and the local density approximation. To model the alloys,16-atom supercells with the 2 × 2 × 2 dimensions are used and the dependency of the lattice parameter, bulk modulus,electronic structure, energy band gap, and optical bowing on the concentration x are analyzed. The results indicate that the ternary Tl_xGa_(1-x) As alloys have an average band gap bowing parameter of 4.48 eV for semiconductor alloys and 2.412 eV for semimetals. It is found that the band gap bowing strongly depends on composition and alloying a small Tl content with GaAs produces important modifications in the band structures of the alloys. 展开更多
关键词 methods of electronic structure calculations electron density of states and band structure of crys-talline solids electronic structure of disordered solid
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Three distinct optical-switching states in phase-change materials containing impurities:From physical origin to material design 被引量:2
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作者 Chaobin Bi Kaicheng Xu +4 位作者 Chaoquan Hu Ling Zhang Zhongbo Yang Shuaipeng Tao Weitao Zheng 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2021年第16期118-125,共8页
Ge2 Sb2 Te5 is the most widely utilized chalcogenide phase-change material for non-volatile photonic applications,which undergoes amorphous-cubic and cubic-hexagonal phase transition under external excitations.However... Ge2 Sb2 Te5 is the most widely utilized chalcogenide phase-change material for non-volatile photonic applications,which undergoes amorphous-cubic and cubic-hexagonal phase transition under external excitations.However,the cubic-hexagonal optical contrast is negligible,only the amorphous-cubic phase transition of Ge_(2)Sb_(2)Te_(5) is available.This limits the optical switching states of traditional active displays and absorbers to two.We find that increasing structural disorder difference of cubic-hexagonal can increase optical contrast close to the level of amorphous-cubic.Therefore,an amorphous-cubichexagonal phase transition with high optical contrast is realized.Using this phase transition,we have developed display and absorber with three distinct switching states,improving the switching performance by 50%.Through the combination of first-principle calculations and experiments,we reveal that the key to increasing structural disorder difference of amorphous,cubic and hexagonal phases is to introduce small interstitial impurities(like N)in Ge2 Sb2 Te5,rather than large substitutional impurities(like Ag)previously thought.This is explained by the formation energy and lattice distortion.Based on the impurity atomic radius,interstitial site radius and formation energy,C and B are also potential suitable impurities.In addition,introducing interstitial impurities into phase-change materials with van der Waals gaps in stable phase such as GeSb_(4) Te_(7),GeSb_(2) Te_(4),Ge_(3)Sb_(2) Te_(6),Sb_(2)Te_(3) will produce high optical contrast amorphous-metastable-stable phase transition.This research not only reveals the important role of interstitial impurities in increasing the optical contrast between metastable-stable phases,but also proposes varieties of candidate matrices and impurities.This provides new phase-change materials and design methods for non-volatile optical devices with multi-switching states. 展开更多
关键词 Phase change materials IMPURITIES Three states structural disorder Photonic applications
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Synthesis and Crystal Structure of 2-Dehydroabietyl-5-ethylsulfanyl-1,2,3,4-tetrazole 被引量:2
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作者 苏桂发 霍丽妮 +2 位作者 黄婉云 王恒山 潘英明 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2009年第6期693-698,共6页
Six novel tetrazoles were designed, synthesized and characterized by NMR and elemental analysis. 2-Dehydroabietyl-5-ethylsulfanyl-1,2,3,4-tetrazole (4b), C23H34N4S, was structurally determined by single-crystal X-ra... Six novel tetrazoles were designed, synthesized and characterized by NMR and elemental analysis. 2-Dehydroabietyl-5-ethylsulfanyl-1,2,3,4-tetrazole (4b), C23H34N4S, was structurally determined by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group P212121, with a = 7.391(3), b = 12.580(3), c = 24.036(8) A^°, V= 2234.8(13) A^°^3, Z = 4, M, = 398.60, Dc = 1.185 g/cm^3, μ = 0.160 mm^-1, F(000) = 864, the final R = 0.0499 and wR = 0.0638 for 1228 observed reflections with I 〉 2σ(I). There are four rings in the crystal structure, and C(14) adopts the R absolute configuration. In addition, disordered C(19), C(20), C(21), C(22) and C(23) exist in the crystal structure. 展开更多
关键词 2-dehydroabietyl-5-ethylsulfanyl-1 2 3 4-tetrazole synthesis crystal structure structural disorder
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Synthesis and Crystal Structure of 2-Ethoxycarbonylmethyl-8-chloro-3a,4-dihydro-3a-methyl-chromeno[4,3-c]pyrazol-3(2H)-one 被引量:1
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作者 赵培亮 周中振 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2010年第8期1280-1283,共4页
The crystal structure of the title compound 2-ethoxycarbonylmethyl-8-chloro-3a,4-dihydro-3a-methyl-chromeno[4,3-c]pyrazol-3(2H)-one(C15H15ClN2O4,Mr = 322.74) has been prepared and determined by single-crystal X-ra... The crystal structure of the title compound 2-ethoxycarbonylmethyl-8-chloro-3a,4-dihydro-3a-methyl-chromeno[4,3-c]pyrazol-3(2H)-one(C15H15ClN2O4,Mr = 322.74) has been prepared and determined by single-crystal X-ray diffraction.The crystal is of orthorhombic,space group Pccn with a = 16.7246(10),b = 19.6626(12),c = 9.3013(6) ,V = 3058.7(3) 3,Z = 8,Dc = 1.402 g/cm3,μ = 0.269 mm-1,F(000) = 1344,the final R = 0.0506 and wR = 0.1464 for 2568 reflections with I 〉 2σ(I).In addition,disordered C(14) and C(15) atoms exist in the crystal structure. 展开更多
关键词 chromeno[4 3-c]pyrazol-3(2H)-one SYNTHESIS insecticidal activity crystal structure structural disorder
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Carbon honeycomb structure with high axial thermal transport and strong robustness
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作者 Wei-Jun Ren Shuang Lu +2 位作者 Cui-Qian Yu Jia He Jie Chen 《Rare Metals》 SCIE EI CAS CSCD 2023年第8期2679-2687,共9页
Thermal transport properties of low-dimensional nanomaterials are highly anisotropic and sensitive to the structural disorder,which can greatly limit their applications in heat dissipation.In this work,we unveil that ... Thermal transport properties of low-dimensional nanomaterials are highly anisotropic and sensitive to the structural disorder,which can greatly limit their applications in heat dissipation.In this work,we unveil that the carbon honeycomb structures which have high in-plane thermal conductivity simultaneously possess high axial thermal conductivity.Based on non-equilibrium molecular dynamics simulations,we find that the intrinsic axial thermal conductivity of carbon honeycomb structure reaches 746 W·m^(-1)·K^(-1)at room temperature,comparable to that of good heat dissipation materials such as hexagonal boron nitride.By comparing the phonon transmission spectrum between carbon honeycombs and few layer graphene,the physical mechanism responsible for the high axial thermal conductivity of carbon honeycombs is discussed.More importantly,our simulation results further demonstrate that the high axial thermal conductivity of carbon honeycomb structure is robust to the structural disorder,which is a common issue during the mass production of the carbon honeycomb structure.Our study suggests that the carbon honeycomb structure has unique advantages to serve as the thermal management material for practical applications. 展开更多
关键词 Carbon honeycomb Thermal conductivity Molecular dynamics simulation Phonon transmission structural disorder
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