Ordering of the α-Fe(Si) Crystallization Phase in Annealed Fe_(73.5)Cu_1Mo_3Si_(13.5)B_9 Alloy

The ordering of the α-Fe(Si) crystallization phase in annealed Fe73.5Cu1Mo3Si13.5B9 alloy has been studied using XRD method. The α-Fe(Si) phase in Fe73.5Cu1Mo3Si13.5B9 alloy annealed at 460℃ for 1 h consists of the DO3-type ordered region with spherical shape and disordered region. The size of DO3 ordered region increases with the annealing temperature. When the annealing temperature is 560℃, the size of the ordered region in the α-Fe(Si) grain is 14.0nm,which is nearly as large as that of the α-Fe(Si) grain (14.2 nm) and the degree of order of the α-Fe(Si) phase is about 0.78. When Fe73.5Cu1 Mo3Si13.5B9 amorphous alloy is annealed at 520℃， with the increment of the annealing time, the shape of the DO3 ordered region in the α-Fe(Si) phase is spheroidal at the beginning of the annealing and becomes spherical and has asize of 12.8 nm when the annealing time is 60 min. In addition, the DO3 superlattice lines of the α-Fe(Si) phase will vanish if Fe73.5Cu1Mo3Si13.5 B9 amorphous alloy is annealed for 1 h at 750℃.

Phase separation-hydrogen etching-derived Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies boosting superior sodium-ion storage kinetics

Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.

Phase field crystal study of the crystallization modes within the two-phase region

Using the phase field crystal approach, the crystallization process within the liquid-solid coexistence region is inves- tigated for a square lattice on an atomic scale. Two competing growth modes, i.e., the diffusion-controlled growth through long-range atomic migration in liquid and the diffusionless growth through local atom rearrangement, which give rise to two completely different crystallization behaviors, are compared. In the diffusion-controlled regime, the interface migrates in a layerwise manner, leading to a gradual change of crystal morphology from truncated square to four-fold symmetric dendrite with the increase of driving force. For the diffusionless growth mode, a single crystal with no significant density change occupies the whole system at a faster rate while exhibiting a small growth anisotropy. The competition between these two modes is also discussed from the key input of the phase field crystal model： the correlation function.

PHASE SEPARATION AND CRYSTALLIZATION OF CHALCOGENIDE GLASSES

In this paper the experimental results associated until the phase separation and nucleation and crystallization of chalcogenidc glasses are described. Experi-ments demonstrate that the phas separation may be affected by small amount of additives. It has been found that some chalcogenide glasses could be converted into glass-ceramics without phase separation. The different mechanisms of nucleated crystallization of chalcogenide glasses are discussed and propossed.

Crystallization Process of Superlattice-Like Sb/SiO_2 Thin Films for Phase Change Memory Application

After compositing with SiO_2 layers, it is shown that superlattice-like Sb/SiO_2 thin films have higher crystallization temperature（~240°C）, larger crystallization activation energy（6.22 e V）, and better data retention ability（189°C for 10 y）. The crystallization of Sb in superlattice-like Sb/SiO_2 thin films is restrained by the multilayer interfaces. The reversible resistance transition can be achieved by an electric pulse as short as 8 ns for the Sb（3 nm）/SiO_2（7 nm）-based phase change memory cell. A lower operation power consumption of 0.09 m W and a good endurance of 3.0 × 10~6 cycles are achieved. In addition, the superlattice-like Sb（3 nm）/SiO_2（7 nm） thin film shows a low thermal conductivity of 0.13 W/（m·K）.

Effect of Plasma Spheroidization Process on the Microstructure and Crystallographic Phases of Silica, Alumina and Nickel Particles

During the plasma spheroidization process powders undergo different changes in their microstructures and crystal phases. In this paper, simple calculation of heat transfer between the plasma and a suspended particle was performed based on three hypotheses for the purpose of guiding experiments. Experimental investigation of the crystal phases and microstructural changes during the plasma processing was made using silica, alumina and nickel powders as starting materials. It has been revealed from the experimental results that these materials undergo different changes in crystal phases and microstructures, and these changes are essentially determined by the structures, properties and aggregate states of the starting materials.

Effects of Additive AlCl_3 on Crystal Phase, Particle Size and Microstructural Parameters of Nanocrystalline TiO_2 Prepared by HF-PCVD

Nanocrystalline TiO2 was prepared by high frequency plasma chemical vapor deposition (HF-PCVD). The effects of additive AlCl3 on crystal phase, particle size and microstructurai parameters of TiO2 nanocrystallites were investigated by X-ray diffraction(XRD) and transmission electron microscopy (TEM). The nanocrystallites obtained experimentally are mixture of anatase and rutile, the uniform diameters of particles are about 30 nm. The phase transformation from anatase to rutile was accelerated by AlCl3, and rutile content is increased from 26.7 wt pct to 53.6 wt pct with increasing of addition of AlCl3 from 0.0 wt pct to 5.0 wt pct. The particle size is reduced and the size distribution becomes very narrow. The crystal lattice constants have the trend to decrease, and celi volumes appear as shrinkable.

Bichromatic coherent random lasing from dye-doped polymer stabilized blue phase liquid crystals controlled by pump light polarization

In this paper,we investigate the bichromatic coherent random lasing actions from the dye-doped polymer stabilized blue phase liquid crystals.Two groups of lasing peaks,of which the full widith at half maximum is about 0.3 nm,are clearly observed.The shorter-and longer-wavelength modes are associated with the excitation of the single laser dye（DCM） monomers and dimers respectively.The experimental results show that the competition between the two groups of the lasing peaks can be controlled by varying the polarization of the pump light.When the polarization of the pump light is rotated from 0？to 90？,the intensity of the shorter-wavelength lasing peak group reduces while the intensity of the longer-wavelength lasing peak group increases.In addition,a red shift of the longer-wavelength modes is also observed and the physical mechanisms behind the red-shift phenomenon are discussed.

Phase Behavior of BaLn_2Mn_2O_7 (Ln=Rare Earth) with a Layered Perovskite Structure

Many phases appear in BaLn 2Mn 2O 7 family (Ln=rare earth) belonging to one of the Ruddlesden-Popper type compounds, depending upon the experimental conditions such as heating conditions when prepared and composition. Some of these phases were characterized by powder X-ray diffraction method using Rietveld analysis. These phases have only a little difference in crystal structure which has fundamentally K 2NiF 4 type structure, although the X-ray diffraction patterns are clearly different: a little deformation or tilting of the oxygen octahedron surrounding a central manganese ion composing the main frame of this structure induce these different diffraction patterns. Phase behavior of these compounds, mainly the detailed relation between various phases in BaTb 2Mn 2O 7, was refined including the data of high temperature X-ray diffractometry.

Optical simulation of in-plane-switching blue phase liquid crystal display using the finite-difference time-domain method

The finite-difference time-domain method is used to simulate the optical characteristics of an in-plane switching blue phase liquid crystal display.Compared with the matrix optic methods and the refractive method,the finite-difference timedomain method,which is used to directly solve Maxwell＇s equations,can consider the lateral variation of the refractive index and obtain an accurate convergence effect.The simulation results show that e-rays and o-rays bend in different directions when the in-plane switching blue phase liquid crystal display is driven by the operating voltage.The finitedifference time-domain method should be used when the distribution of the liquid crystal in the liquid crystal display has a large lateral change.

Competition between acidic sites and hydrogenation sites in Cu/ZrO_(2) catalysts with different crystal phases for conversion of biomass-derived organics

Oxides with different crystal phases can have important effects on the configuration of surface atoms,which can further affect the distribution of hydrogenation sites and acidic sites as well as the competitions of these varied types of catalytic sites.This could be potentially used to tailor the distribution of the products.In this study,zirconium oxides with different crystal phases supported copper catalysts were prepared for the hydrogenation of the biomass-derived furfural,vanillin,etc.The results showed that both calcination temperature and Cu species affected the shift of zirconia from tetragonal phase to the monoclinic phase.Monoclinic zirconia supported copper catalyst can effectively catalyze the hydrogenation of furfural to furfuryl alcohol via hydrogenation route due to its low amount of Brønsted acidic sites,although the surface area and the exposed metallic Cu surface area were much lower than the tetragonal zirconia supported copper catalyst.Zirconia with tetragonal or tetragonal/monoclinic phases supported copper catalysts contain abundant acidic sites and especially the Br?nsted acidic sites,which catalyzed mainly the conversion of furfural via the acid-catalyzed routes such as the acetalization,rather than the hydrogenation.The acidic sites over the Cu/ZrO_(2)catalyst played more predominant roles than the hydrogenation sites in determining the conversion of the organics like furfural and vanillin.

Faceting transitions in crystal growth and heteroepitaxial growth in the anisotropic phase-field crystal model

We modify the anisotropic phase-field crystal model （APFC）, and present a semi-implicit spectral method to numerically solve the dynamic equation of the APFC model. The process results in the acceleration of computations by orders of magnitude relative to the conventional explicit finite-difference scheme, thereby, allowing us to work on a large system and for a long time. The faceting transitions introduced by the increasing anisotropy in crystal growth are then discussed. In particular, we investigate the morphological evolution in heteroepitaxial growth of our model. A new formation mechanism of misfit dislocations caused by vacancy trapping is found. The regular array of misfit dislocations produces a small-angle grain boundary under the right conditions, and it could significantly change the growth orientation of epitaxial layers.

Preparation of High-Quality Poly-Si Films by a Solid Phase Crystallizing Method

A solid phase crystallizing method has been developed to grow a Si crystal at tem-peratures as low as 550 ℃. Using this method, a high-quality thin-film polycrystalline silicon (Poly-Si) was obtained. The largest grain size, examined with X-ray diffraction spectroscopy and scanning electron microscopy images of recrystallized samples, is approximately 1 /μm for substrate temperature at 300 ℃ and annealed at 550℃ for 3 hours.

Asymmetric dynamic phase holographic grating in nematic liquid crystal

A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal（NLC） was presented.An oblique incidence beam was used to record the thin asymmetric dynamic phase holographic grating.The diffraction efficiency we achieved is more than 40%,exceeding the theoretical limit for symmetric profile gratings.Both facts can be explained by assuming that a grating with an asymmetric saw-tooth profile is formed in the NLC.Finally,physical mechanism and mathematical model for characterizing the asymmetric phase holographic grating were presented,based on the photo-refractive-like（PR-like） effect.

Crystal Phases and Chemical Stabilities of YSi2 Powders Fabricated from Low and High Purity Si and Y Powders

Y-Si compounds with the composition of Y:Si = 1:2 were fabricated using Yttrium and Silicon raw powders with low and high purity in various atmospheres and temperatures. Although the latest Y-Si phase diagram shows that the α- and β-YSi2 phases are the stable phases for the stoichiometric composition of Y:Si = 1:2, the current experimental results suggest that the high temperature phase with the hexagonal structure, β-Y3Si5, would be the stable phase for this composition, and that the high temperature phase with the orthorhombic structure, β-YSi2, would be the meta-stable phase with high oxygen impurity content. It was demonstrated that YSi2 powders possess much superior chemical stability than Yttrium metal. It was found that the best dispersing solvent was 2-propanol for YSi2 powder.

A high precision phase reconstruction algorithm for multi-laser guide stars adaptive optics

Adaptive optics（AO） systems are widespread and considered as an essential part of any large aperture telescope for obtaining a high resolution imaging at present.To enlarge the imaging field of view（FOV）,multi-laser guide stars（LGSs） are currently being investigated and used for the large aperture optical telescopes.LGS measurement is necessary and pivotal to obtain the cumulative phase distortion along a target in the multi-LGSs AO system.We propose a high precision phase reconstruction algorithm to estimate the phase for a target with an uncertain turbulence profile based on the interpolation.By comparing with the conventional average method,the proposed method reduces the root mean square（RMS） error from 130 nm to 85 nm with a 30% reduction for narrow FOV.We confirm that such phase reconstruction algorithm is validated for both narrow field AO and wide field AO.

CRYSTAL STRUCTURE OF A LONG－PERIOD ORDERED PHASE IN Fe－C MARTENSITE AND COMPUTER SIMULATION OF ITS ELECTRON DIFFRACTION PATTERNS

Different structure models of a long-period ordered phase in Fe-C martenstie formed during aging have been checked by computer simulation of electron diffraction(ED) patterns based on these models.The results showed that the simulated ED pattern of γ'-FexC(Ⅱ) model proposed by the present authors is in good agreement with experimentally observed ED pattern.It was also confirmed that the incommensurate superperiod stems from the coexistence of several γ'-Fe_xC(H) phases with different superperiods.The Fe(144)C(24)(Fe6C) model proposed by Uwakweh et al.generated ED patterns remarkably different from the experimental ones.

Studies on the Phase Behavior of Lyotropic Liquid Crystal in DAD/C_4OH/n-C_8H_(18)/D_2O System

The lytropic liquid crystals in dodecanic acid diethanolamine (DAD) /n-butanol (C4OH) /octane (n-C8H18) /deuteron (D2O) system were studied to determine the phase regions and were investigated by 2H-NMR spectroscopy,optical polarizing microscope and small-angle X-ray diffraction (SAXD) methods.The results indicate that the lamellar,hexagonal and cubic liquid crystals all exist in the above system.Keeping the weight ratio of DAD and C4OH constant,the microphase Structure,2H quadruple splitting and the interlayer spacing are all changed with the addition of deuteron.

Crystal phase control and ignition properties of HNS/CL-20 composite microspheres prepared by microfluidics combined with emulsification techniques

Improved controllability and energy density of ignition agents are of great significance for the devel-opment of energetic composite materials.In this study,droplet microfluidics and emulsification tech-niques were combined to prepare HNS/CL-20 composite microspheres with polyglycidyl azide polymer(GAP)as the binder.The influence of binder content on the morphology of microspheres was investi-gated,and the microspheres were characterized and tested for particle size,crystal structure,thermal decomposition,dispersibility,mechanical sensitivity,combustion behavior and detonation performance.The results showed that microspheres prepared with a binder content of 3%had higher sphericity and particle size uniformity.The microspheres retained the crystal structure of both HNS and CL-20(ε-type).Compared with raw HNS,the microspheres had higher apparent activation energy,better safety per-formance,and good dispersibility.The ignition experiments and detonation performance tests show that HNS/CL-20 composite microspheres have excellent ignition performance,obvious combustion flame,and significant energy release effects,which are expected to achieve high energy and high-speed response of the igniter,thus improving the ignition reliability in special environments or systems.

High catalytic performance of CuCe/Ti for CO oxidation and the role of TiO_(2)

CuCe/Ti-A and CuCe/Ti-R catalysts were prepared using anatase TiO_(2)(TiO_(2)-A)and rutile TiO_(2)(TiO_(2)-R)as supports using the incipient wetness impregnation method for the carbon monoxide(CO)oxidation reaction and were compared with a CuCe-C catalyst prepared using the co-precipitation method.The CuCe/Ti-A catalyst exhibited the highest activity,with complete CO conversion at 90℃,when the gas hourly space velocity was 24000 ml.g^(-1).h^(-1) and the CO concentration was approximately 1%(vol).A series of characterizations of the catalysts revealed that the CuCe/Ti-A catalyst has a larger specific surface area,more Cu+species and oxygen vacancies,and the Cu species of CuCe/Ti-A catalyst is more readily reduced.In situ FT-IR results indicate that the bicarbonate species generated on the CuCe/Ti-A catalyst have lower thermal stability than the carbonate species on CuCe/Ti-R,and will decompose more readily to form CO_(2).Therefore,CuCe/Ti-A has excellent catalytic activity for CO oxidation.