Facile synthesized Cu-SnO2 anode materials with three-dimensional metal cluster conducting architecture for high performance lithium-ion batteries

Metal oxide anode material is one of promising candidates for the next-generation LIBs, due to its high theoretical capacity and low cost. The poor conductivity and huge volume change during charge/ discharge, however, restrict the commercialization of metal oxide anode material. In this work, we design a novel Cu-SnO2 composite derived from Cu6Sn5 alloy with three dimensional （3D） metal cluster conducting architecture. The novel Cu structure penetrates in the composite particles inducing high conductivity and space-confined SnO2, which restrict the pulverization of SnO2 during lithiation/ delithiation process. The optimized Cu-SnO2 composite anode delivers an initial discharge capacity of 933.7 mA h/g and retains a capacity of 536.1 mA h/g after 200 cycles, at 25℃ and a rate of 100 mA/g. Even at the high rate of 300 mA/g, the anode still exhibits a capacity of more than 29% of that tested at 50 mA/g. Combining with the phase and morphology analysis, the novel Cu-SnO2 composite not only has good electrical conductivity, but also possesses high theoretical capacity （995 mAh/g）, which may pave a new way for the design and construction of next-generation metal oxide anode materials with high power and cycling stability.

Optically driven intelligent computing with ZnO memristor

Artificial vision is crucial for most artificial intelligence applications.Conventional artificial visual systems have been facing challenges in terms of real-time information processing due to the physical separation of sensors,memories,and processors,which results in the production of a large amount of redundant data as well as the data conversion and transfer between these three components consuming most of the time and energy.Emergent optoelectronic memristors with the ability to realize integrated sensing-computing-memory(ISCM)are key candidates for solving such challenges and therefore attract increasing attention.At present,the memristive ISCM devices can only perform primary-level computing with external light signals due to the fact that only monotonic increase of memconductance upon light irradiation is achieved in most of these devices.Here,we propose an all-optically controlled memristive ISCM device based on a simple structure of Au/ZnO/Pt with the ZnO thin film sputtered at pure Ar atmosphere.This device can perform advanced computing tasks such as nonvolatile neuromorphic computing and complete Boolean logic functions only by light irradiation,owing to its ability to reversibly tune the memconductance with light.Moreover,the device shows excellent operation stability ascribed to a purely electronic memconductance tuning mechanism.Hence,this study is an important step towards the next generation of artificial visual systems.

Application of SEM-CL system in the characterization of material microstructures

Cathodoluminescence(CL)characterization technology refers to a technical approach for evaluating the luminescent properties of samples by collecting photon signals generated under electron beam excitation.By detecting the intensity and wavelength of the emitted light,the energy band structure and forbidden bandwidth of a sample can be identified.After a CL spectrometer is mounted on a scanning electron microscope(SEM),functions are integrated,such as high spatial resolution,morphological observation,and energy-dispersive spectroscopy(EDs)to analyze samples,offering unique and irreplaceable advantages for the microstructural analysis of certain materials.This paper reviews the applications of SEM-CL systems in the characterization of material microstructures in recent years,illustrating the utility of the SEM-CL system in various materials including geological minerals,perovskite materials,semiconductor materials,non-metallic inclusions,and functional ceramics through typical casestudies.

Application of BIB polishing technology in cross-section preparation of porous, layered and powder materials: A review

For the accuracy of experimental results, preparing a high quality polished surface and cross-section of the materials for further analysis using electron backscattered diffraction (EBSD), electron probe microanalysis (EPMA), and scanning probe microscopy (SPM) is extremely important. Broad ion beam (BIB) polishing, a method based on the principle of ion bombardment, has irreplaceable advantages. It makes up for the drawbacks and limitations of traditional polishing methods such as mechanical polishing, electrochemical polishing, and chemical polishing. The ions will not leave the bombardment area during polishing, which makes the BIB method suitable for porous materials. The energy of the ion beam can be adjusted according to the sample to reduce the deformation and strain of the polishing area, especially for fragile, soft, and hard materials. The conditions that need to be controlled during BIB polishing are simple. This paper demonstrated the unique advantages of BIB polishing technology in porous, layered and powder materials characterization through some typical application examples, and guided more researchers to understand and utilize BIB polishing technology in the development of new applications.

Twinning,phase boundary structure and development of high coercivity in Fe-rich Sm_(2)Co_(17)-type magnets

The microstructure of twinning as well as the phase boundary between 1:5 H and 2:17 R phase in Fe-rich Sm_(2)Co_(17)-type magnets was characterized at atomic scale using nanobeam diffraction and highresolution STEM-HAADF imaging,and the reason for the dramatic increase of coercivity during slow cooling was investigated based on the microchemistry analysis.The twinning relationship in the 2:17 R phase originates from ordered substitution of Sm atoms by Co-Co atomic pairs on every three(3033)and(3033)planes,leading to formation of two corresponding equivalent twin variants.The basal plane of the 2:17 R phase,the 1:3 R platelet phase across the 2:17 R cell and the 1:5 H cell boundary phase between two adjacent 2:17 R cells all can act as effective twin boundary.The cell boundary phase is precipitated along the pyramidal habit plane,and a fully coherent phase boundary(PB)is formed between the 1:5 H and 2:17 R phases with the orientation relationship to be PB//(1121)1:5 H//(1011)_(2):17 R.The phase boundary may either be parallel to or intersect with the pyramidal planes occupied by Co-Co atomic pairs.The substantial increase of coercivity during slow cooling is ascribed to the development of large gradient of the elements concentration within the cell boundary phase,resulting in large gradient of domain wall energy,and thus the pinning strength of the cell boundary phase against magnetic domain wall motion is significantly enhanced.

In situ real-time study buckling behavior of boron nitride nanotubes with axial compression by TEM

Boron nitride nanotubes(BNNTs)were treated as brittle materials and could be used to enhance the composite mechanical properties.Many approaches were used to verify the theoretical prediction experimentally,but how to in situ real-time characterize nanomechanical properties of BNNTs was still interested to the researchers.An in situ transmission electron microscopy(TEM)equipped with a force transducer holder had been used to study the structure evolution behavior of BNNTs with axial compression.Real-time video and the force transducer had been used synchronously to record the whole force loading process where the mechanical deformation of BNNT began,buckled and ended with fracture.An in dividual ultrathin BNNT was employed to con duct the loading test.The results showed that the elastic deformation happened on the BNNT.Young's modulus?1.05-1.37 Tpa and elasticity coefficient?198.7-255.9 N/m of BNNT were calculated by Euler formula and Hooker's law,respectively.

Development of the high-strength ductile ferritic alloys via regulating the intragranular and grain boundary precipitation of G-phase

A typical G-phase strengthened ferritic model alloy(1Ti:Fe-20Cr-3Ni-1Ti-3Si,wt.%)has been carefully studied using both advanced experimental(EBSD,TEM and APT)and theoretical(DFT)techniques.During the classic“solid solution and aging”process,the superfine(Fe,Ni)_(2)TiSi-L2_(1)particles densely precipitate within the ferritic grain and subsequently transform into the(Ni,Fe)_(16)Ti_(6)Si_(7)-G phase.In the meanwhile,the elemental segregation at grain boundaries and the resulting precipitation of a large amount of the(Ni,Fe)_(16)Ti_(6)Si_(7)-G phase are also observed.These nanoscale microstructural evolutions result in a remarkable increase in hardness(100-300 HV)and severe embrittlement.When the“cold rolling and aging”process is used,the brittle fracture is effectively suppressed without loss of nano-precipitation strengthening ef-fect.Superhigh yield strength of 1700 MPa with 4%elongation at break is achieved.This key improvement in mechanical properties is mainly attributed to the pre-cold rolling process which effectively avoids the dense precipitation of the G-phase at the grain boundary.These findings could shed light on the further exploration of the precipitation site via optimal processing strategies.