Accelerated Sequential Deposition Reaction via Crystal Orientation Engineering for Low-Temperature,High-Efficiency Carbon-Electrode CsPbBr_(3) Solar Cells

Low-temperature,ambient processing of high-quality CsPbBr_(3)films is demanded for scalable production of efficient,low-cost carbon-electrode perovskite solar cells(PSCs).Herein,we demonstrate a crystal orientation engineering strategy of PbBr_(2)precursor film to accelerate its reaction with CsBr precursor during two-step sequential deposition of CsPbBr_(3)films.Such a novel strategy is proceeded by adding CsBr species into PbBr_(2)precursor,which can tailor the preferred crystal orientation of PbBr_(2)film from[020]into[031],with CsBr additive staying in the film as CsPb_(2)Br_(5)phase.Theoretical calculations show that the reaction energy barrier of(031)planes of PbBr_(2)with CsBr is lower about 2.28 eV than that of(O2O)planes.Therefore,CsPbBr_(3)films with full coverage,high purity,high crystallinity,micro-sized grains can be obtained at a low temperature of 150℃.Carbon-electrode PSCs with these desired CsPbBr_(3)films yield the record-high efficiency of 10.27%coupled with excellent operation stability.Meanwhile,the 1 cm^(2)area one with the superior efficiency of 8.00%as well as the flexible one with the champion efficiency of 8.27%and excellent mechanical bending characteristics are also achieved.

Influence of spiral crystal selector on crystal orientation of single crystal superalloy

To increase efficiency and improve performance, reducing cost and emissions, advanced single crystal Ni-based superalloys are required in aerospace propulsion and power generating gas turbines. With the development of alloy, significant improvements in casting techniques have been achieved by introducing the directionally solidified （DS） casting process followed by single crystal （SX） technique. The deviation of preferred orientation of single crystal superalloys is one of the most important defects in casting. In directional solidification equipment with high temperature gradient, single crystal specimens of DZ417G alloy were prepared successfully by the modified Bridgeman method with spiral grain selector. The orientation was investigated by means of X-ray diffraction （XRD） and electron backscattered diffraction （EBSD）.The results show that the crystal selector with a smaller angle can effectively reduce the deviation of preferred orientation.

Effect of crystal orientation on tensile mechanical properties of single-crystal tungsten nanowire

Based on the high-purity single-crystal tungsten nanowire firstly prepared by the metal-catalyzed vapor-phase reaction method, molecular dynamics method was used to calculate tensile stress-strain curves and simulate microscopic deformation structures of the single-crystal tungsten nanowires with different crystal orientations of 〈100〉, 〈110〉and 〈111〉, in order to reveal the effect of crystal orientation on their tensile mechanical properties and failure mechanisms. Research results show that all of the stress-strain curves are classified into four stages： elastic stage, damage stage, yielding stage and failure stage, where 〈100〉orientation has a special hardening stage after yielding and two descending stages. The crystal orientation has little effect on elastic modulus but great effect on tensile strength, yielding strength and ductility, depending on different atomic surface energies and principal sliding planes. The calculated values of elastic modulus are in good agreement with the tested values of elastic modulus.

Manipulating Crystal Growth and Secondary Phase PbI_(2)to Enable Efficient and Stable Perovskite Solar Cells with Natural Additives

In perovskite solar cells(PSCs),the inherent defects of perovskite film and the random distribution of excess lead iodide(PbI_(2))prevent the improvement of efficiency and stability.Herein,natural cellulose is used as the raw material to design a series of cellulose derivatives for perovskite crystallization engineering.The cationic cellulose derivative C-Im-CN with cyano-imidazolium(Im-CN)cation and chloride anion prominently promotes the crystallization process,grain growth,and directional orientation of perovskite.Meanwhile,excess PbI_(2)is transferred to the surface of perovskite grains or formed plate-like crystallites in local domains.These effects result in suppressing defect formation,decreasing grain boundaries,enhancing carrier extraction,inhibiting non-radiative recombination,and dramatically prolonging carrier lifetimes.Thus,the PSCs exhibit a high power conversion efficiency of 24.71%.Moreover,C-Im-CN has multiple interaction sites and polymer skeleton,so the unencapsulated PSCs maintain above 91.3%of their initial efficiencies after 3000 h of continuous operation in a conventional air atmosphere and have good stability under high humidity conditions.The utilization of biopolymers with excellent structure-designability to manage the perovskite opens a state-of-the-art avenue for manufacturing and improving PSCs.

Effect of crystal orientations and precipitates on corrosion behavior of Al-Cu-Li single crystals

The effect of the crystal orientations and precipitates on the corrosion behavior of Al-Cu-Li single crystals was studied by scanning electron microscopy, transmission electron microscopy, optical microscopy, immersion testing in exfoliation corrosion solution, and electrochemical testing. The results show that the corrosion rates of different orientations of the aged Al-Cu-Li alloy increase in the order of (001) 1 phase deteriorated the corrosion resistance of the Al-Cu-Li alloy, and the degree of deterioration differed in different crystal plane orientations. The severe localized corrosion of the aged alloy propagates along the crystallography and extends along the {111}Alplane in the form of corrosion bands.

Imaging the crystal orientation of 2D transition metal dichalcogenides using polarization-resolved second-harmonic generation

We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perform polarization-resolved second-harmonic generation(PSHG)imaging in a stationary,raster-scanned chemical vapor deposition(CVD)-grown WS2 flake,in order to obtain with high precision a spatially resolved map of the orientation of its main crystallographic axis(armchair orientation).By fitting the experimental PSHG images of sub-micron resolution into a generalized nonlinear model,we are able to determine the armchair orientation for every pixel of the image of the 2D material,with further improved resolution.This pixel-wise mapping of the armchair orientation of 2D WS2 allows us to distinguish between different domains,reveal fine structure,and estimate the crystal orientation variability,which can be used as a unique crystal quality marker over large areas.The necessity and superiority of a polarization-resolved analysis over intensity-only measurements is experimentally demonstrated,while the advantages of PSHG over other techniques are analysed and discussed.

Crystal orientation and corrosion resistance of CuNi10Fe1Mn alloy billet under rotating electromagnetic field

CuNi10Fe1Mn alloy billet under rotating electromagnetic field (REF) was characterized in this work. The change of the crystal orientation was first explored by X-ray diffraction (XRD) and scanning election microscope (SEM); the corrosion resistance was done by three electrodes system, and the natural sea water was used as corrosion medium. The results demonstrate that the strongest crystal orientation is transformed from crystal plane (200) to (111); moreover, the crystal plane (111) whose intensity is the strongest on the cross section and vertical section with REF causes the tubes be rolled easily, and the corrosion resistance of the billet is increasing with REF. As a result, properties of CuNi10Fe1Mn alloy tubes can be improved by REF.

Relationship between solid/liquid interface and crystal orientation for pure magnesium solidified in fashion of cellular crystal

The relationship between the solid/liquid interface and the crystal orientation for pure magnesium,which grows in fashion of cellular crystal in unidirectional solidification,was investigated.The results show that the energy of the solid/liquid interface is the lowest during cellular crystal growth of pure magnesium;and the solid/liquid interface is covered by the basal face{0001}and by the crystal face made up of three atoms located at the orientation{0001}0100and two atoms located at the inner of magnesium crystal cell.The strongest bond is formed in the direction of 61.9°viating from the growth direction,and the second strong bond is formed in the directions of 8.5°d 47.7°espectively,deviating from the growth direction.The angle between the basal face{0001} and the growth direction is 61.9°he theoretical analysis results are basically consistent with the experimental results from SUSUMU et al.

EFFECT OF ORIENTATION ON STRESS RESPONSE,FRICTION STRESS AND BACK STRESS DURING CYCLIC DEFORMATION IN Al SINGLE CRYSTALS

The symmetrical push-pull fatigue tests at strain amplitude of 2×10~3 with different slip orientation of Al single crystals,were carried out at room temperature in air.The peak stresses of various cycles were measured and the stress-strain hysteresis loops for selected cy- cles were recorded.The energy losses.friction stresses,back stresses and shape

MATRIX INVESTIGATION ON ISAICHEV ORIENTATION RELATIONSHIP

By means of TEM technique the orientation relationships of cementite, precipitated from islands of granular bainite during tempering, with ferrite have been observed. By calculating the eigenvalues and eigenvectors of transformation matrix, Isaichev relationship has been analyzed. The results indicate that Isaichev relationship is indeed the sum of Kurdjumov-Sachs relationship and Pitsch relationship, so the viewpoint that the cementite with Isaichev relationship precipitates from austenite, instead of ferrite, was confirmed. Moreover, the matrix calculation shows that three reported orientation relationships among austenite, ferrite and cementite in pearlitic transformation cannot be simultaneously valid. (Edited author abstract) 4 Refs.

EFFECT OF SLIP ORIENTATION ON STRESS RESPONSE,INTERNAL FRICTION AND ULTRASONIC ATTENUATION DURING CYCLIC DEFORMATION IN Al SINGLE CRYSTALS

The variation of cyclic stress,internal friction and ultrasonic attenuation during cyclic deformation and relations among them have been investigated with different slip orientation Al single crystals.The results indicate that the value of cyclic stress σ,internal friction Q^(-1)and ultrasonic attenuation △α depend obviously on the slip orientation.There are large differences in above three parameters for different slip orientation Al crystals.In early stage of fatigue life,σ and △α increase and Q^(-1)decreases with cycles N,and △α reached maxi- mum before σ,while Q^(-1)and σ get the valley and the peak,respectively,at same cycles.

ORIENTATION DISTRIBUTION FUNCTIONS FOR MICROSTRUCTURES OF HETEROGENEOUS MATERIALS (Ⅱ)──CRYSTAL DISTRIBUTION FUNCTIONS AND IRREDUCIBLE TENSORS RESTRICTED BY VARIOUS MATERIAL SYMMETRIES

The explicit representations for tensorial Fourier expansion of 3_D crystal orientation distribution functions (CODFs) are established. In comparison with that the coefficients in the mth term of the Fourier expansion of a 3_D ODF make up just a single irreducible mth_order tensor, the coefficients in the mth term of the Fourier expansion of a 3_D CODF constitute generally so many as 2m+1 irreducible mth_order tensors. Therefore, the restricted forms of tensorial Fourier expansions of 3_D CODFs imposed by various micro_ and macro_scopic symmetries are further established, and it is shown that in most cases of symmetry the restricted forms of tensorial Fourier expansions of 3_D CODFs contain remarkably reduced numbers of mth_order irreducible tensors than the number 2m+1 . These results are based on the restricted forms of irreducible tensors imposed by various point_group symmetries, which are also thoroughly investigated in the present part in both 2_ and 3_D spaces.

Orientation-dependent morphological stability of grain boundary groove

Crystal orientation influences the morphological stability of solid–liquid interface during directional solidification of alloy, resulting in the variation of solidified microstructure. In this paper, the morphological evolution near grain boundary grooves（GBGs） with different crystal orientations in a dilute succinonitrile alloy under low temperature gradient and interface velocity is observed in situ. Under experimental conditions, the macroscopic solid–liquid interface is planar and keeps stable, while in GBGs there emerge protrusion and undulation. It is found that the morphological stability of GBG is dependent on crystal orientation. Specifically, for succinonitrile with a body-centered cubic crystal structure, GBGs around the 100 crystal orientation keep stable, while those apart from the 100 crystal orientation become unstable under the same conditions. So it is concluded that 100 crystal orientation favors the morphological stability of GBG.

The Relationship Between Nacreous Layer Color and CaCO_3 Crystal Orientation

The pearl or nacreous layer of mollusk shell is composed of CaCO 3 aragonite crystals. The factors affecting their color are very complex, such as metal elements, chromoprotein, and nucleation materials. we analyzed the crystal orientation of nacreous layers with different color prepared from fresh water clams Hyriopsis cumingii Lea by X ray diffraction . The results show that the crystal CaCO 3 orientation on specific plane is responsible for the color of pearl and nacreous pearl color.

Investigation on the Orientation Transition of Oriented Magnetostrictive TbDyFe Crystals

〈110〉 and 〈112〉 TbDyFe magnetostrictive oriented crystals were prepared by the zone-melting unidirectional solidification method at 240 mmfh and 720 mm/h respectively. 〈112〉 oriented crystals were also obtained with 〈110〉 oriented seeds with the same technique as for growing the 〈112〉 oriented crystals. It is confirmed that this technique is stable for growing the oriented crystals in the TbDyFe alloys. Meanwhile, the variation of orientation, the solidification morphology and the magnetostriction were studied during the transition from 〈110〉 oriented seeds to the 〈112〉 oriented crystal growth. As the growth speeds up, the preferred orientation changed from 〈110〉 to 〈112〉, and its morphology develops from of initial cellular to dendritic gradually. When an axial compressive pre-stress of 10 MPa is applied, the magnetostriction at the bottom, the middle and the top are 972× 10^6, 918 × 10^-6 and 900× 10^-6 at 100 mT respectively. The middle sections with mixed orientations have the same high magnetostriction performance as those with a single preferred orientation, which may be due to its celluar-dendritic morphology.

Recent Advances in Structural Optimization and Surface Modification on Current Collectors for High‑Performance Zinc Anode:Principles,Strategies,and Challenges

The last several years have witnessed the prosperous development of zinc-ion batteries(ZIBs),which are considered as a promising competitor of energy storage systems thanks to their low cost and high safety.However,the reversibility and availability of this system are blighted by problems such as uncontrollable dendritic growth,hydrogen evolution,and corrosion passivation on anode side.A functionally and structurally well-designed anode current collectors(CCs)is believed as a viable solution for those problems,with a lack of summarization according to its working mechanisms.Herein,this review focuses on the challenges of zinc anode and the mechanisms of modified anode CCs,which can be divided into zincophilic modification,structural design,and steering the preferred crystal facet orientation.The possible prospects and directions on zinc anode research and design are proposed at the end to hopefully promote the practical application of ZIBs.

The internal COF features in Dome A of Antarctica revealed by multi-polarization-plane RES

The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition （MPT） and the relationship between greenhouse gas and climate change. The region near Dome A in Antarctica satisfies the conditions for obtaining million-years-old ice since it has low temperatures and low accumulation rates. We analyze the corresponding relation between radar wave features and the crystal orientation fabric （COF） types based on the results of multi-polarization plane radio echo sounding （RES）. The results show that, even in the summit of the ice sheet, the COF type is not perfect, but is an elongated single-pole COF. Principal-axis-orientation differences of the COF among the different periods exist and reveal that the ice flow orientations are not constant but deviate clockwise with the increasing depth. This may be related to the adjacent basal valley or both height and position changes of the summit during the glacial-interglacial periods.

Scale effect mechanism on micro rod upsetting deformation analyzed by crystal plasticity model

To analyze the effect of single grain deformation behaviors on microforming process, a crystal plasticity model was developed considering grains at free surface layer as single grains. Based on the rate-dependent crystal plasticity theory, the analysis of the scale effect mechanism on upsetting deformation of micro rods was performed with respect to specimen dimension, original grain orientation and its distribution. The results show that flow stress decreases significantly with the scaling down of the specimen. The distribution of the grain orientation has an evident effect on flow stress of the micro specimen, and the effect becomes smaller with the progress of plastic deformation. For the anisotropy of single grains, inhomogeneous deformation occurs at the surface layer, which leads to the increase of surface roughness, especially for small specimens. The effect of grain anisotropy on the surface topography can be decreased by the transition grains. The simulation results are validated by upsetting deformation experiments. This indicates that the developed model is suitable for the analysis of microforming processes with characteristics, such as scale dependency, scatter of flow stress and inhomogeneous deformation.

Low frequency damping capacities of commercial pure magnesium

The amplitude-dependent and temperature-dependent low frequency damping capacities of magnesium with 99.96% purity were studied by a dynamic mechanical analyzer. The pure magnesium alloys include CPM1 and CPM2 castings having textures of columnar grains which extraordinarily influence the damping behaviours. The commercial pure magnesium alloy CPM was re-melted to obtain equiaxed grains, which could remove the effect of texture orientation on the damping behaviours of these pure magnesium alloys. The results of strain amplitude-dependent damping spectrums of these pure magnesium alloys show that the pure magnesium with equiaxed grains possesses the highest damping capacity. In temperature-dependent damping plot for all these three pure magnesium alloys, there are two damping peaks P1 and P2 located at 80 and 230 °C, respectively. These two damping peaks are considered to be caused by the interaction between dislocation and point defects, and the movement of grain boundaries, respectively.

Effect of Black Plate on Corrosion Resistance of T5 Tinplate

The effect of black plate on corrosion resistance of T5 tinplate was studied by glow discharge spectrograph, X-ray diffractometer （XRD）, stress tester, roughness tester and metallographic microscope. The result shows that black plate influences corrosion resistance of T5 tinplate intensely. It also indicates that the increase of content of manganese, phosphorus, silicon and aluminum in black plate would reduce the corrosion resistance of T5 tinplate and the increase of degree of crystal orientation on （200） crystal face, ｜X-Y｜ value （internal stress difference within two orientation）, roughness and exposure degree of iron grain after the same acid wash of black plate would enhance the corrosion resistance of T5 tinplate and the grain number of black plate has small effect on corrosion resistance of T5 tinplate.