Organic Compounds Possessing the Plastic Crystalline Phase: Calculation of Their Fusion Enthalpies

For the first time, for different organic and inorganic compounds possessing the plastic crystalline phase, a new semiempirical equation describing dependence of their fusion enthalpies on such physico-chemical quantities as normal melting temperature, surface tension, molar volume and critical molar volume is received on the base of the principle of corresponding states and the energy equipartition theorem. Moreover, the proposed equation allows one to take into account the particularities of one-particle molecular rotation in the plastic crystalline phase.

Synthesis of steel slag ceramics: chemical composition and crystalline phases of raw materials

Two types of porcelain tiles with steel slag as the main raw material （steel slag ceramics） were synthesized based on the CaO-A1203-SiO2 and CaO--MgO-SiO2 systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite, a-quartz, magnetite, and pyroxene crystals （augite and diopside） in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction （XRD） and electron probe X-ray microanalysis （EPMA） results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.

Synthesis and Phase Behavior of Poly(1-alkyne) with Liquid Crystalline-induced Luminescence Enhancement

Poly（1-alkyne） with octoxy spacer —{[HC=C（CH2）8O—terphenyl—CN]}n—（PA8CN） and terphenyl liquid crystalline pendant was synthesized,and the effects of structure on the optical properties,especially the liquid crystallinity behavior of the polymer and monomer were investigated.The monomer was prepared in high yields（92.30%） by coupling and etherification reactions and successfully polymerized in the presence of Rh catalyst and Et3N cocatalyst in high yields with trans-rich（86.27%） stereoregular structure.Compared to the monomer showing mixed monolayer structure,its corresponding polymer PA8CN formed homogeneous monolayer arrangement.Upon photoexcitation,strong blue emission peak of PA8CN appeared at 413 nm[fluorescence quantum yield,ΦF = 68% when excited at 330 nm in tetrahydrofuran（THF） solution].Compared with its solid film photoexcitated at 330 nm at room temperature,the UV light-emitting band of PA8CN solid film from its liquid crystalline with liquid nitrogen quenched rapidly at 236 ℃ was red-shift 10 nm with higher intensity,which may be ascribed to the fact that the effectual conjugation and the order degree of the molecule in the liquid crystalline state of the polymer were enhanced,the energy loss caused by the thermal vibration was decreased,thus resulting in the observed hyperchromic effect.

Crystalline Phase and Decomposition Dynamics of Aluminum Titanate at Different Temperature

The crystalline phase formed during aluminum titanate at 750-1300 ℃ as well as the relationship between its content change and decomposition dynamics was mainly discussed in this paper.Dynamical equation was established for calculating the reaction activation energy.It aimed at providing dynamics basic data for taking up necessary measures to inhibit the decomposition of aluminum titanate.Experimental results showed that aluminum titanate would decompose into TiO2 and corundum at 750-1300 ℃.Content of aluminum titanate would reduce with the increase of decomposition time,and the order of decomposition rates at different temperature was 1100 1200 1000 900 ℃.The decomposition was a chemical reaction with control steps,and could meet the first order reaction dynamic equation-F（G） = [（1-G）-2/3-1] = Kt.According to the calculation,rate constants of different decomposition reaction dynamic equations were K900 = 2.2×10-3,K1000 = 1.2×10-2,K1100 = 4×10-1 and K1200 = 1.5×10-1,and the reaction activation energy ΔGave = 203.21 KJ/mol.

Effect of Solution Concentration on the Electrospray/Electrospinning Transition and on the Crystalline Phase of PVDF

A study was conducted regarding the effect of concentration of poly (vinylidene fluoride) (PVDF)/N,N-dimethylformamide (DMF) and PVDF/DMF/acetone solutions on the transition between electrospray and electrospinning and on the formation of the ? and ? crystalline phases of PVDF. The crystalline phases present in the samples, crystallinity and morphology were determined by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively. Low concentration solutions resulted in films consisting of small droplets (electrospray) containing predominantly the ? phase. High concentration solutions resulted in a non-woven mesh of nano-to-micron diameter fibers (electrospinning) containing exclusively the ? phase. These results showed that, the formation of this phase in the electrospinning is related mainly to the solvent evaporation rate, and not to drawing experienced by the polymer during the process. Solvent type affected the amount of crystalline phase present, the boundary concentration between the two processes and the average diameter of fibers. Meshes processed by electrospinning display a degree of crystallinity higher than the films obtained by electrospray.

Effect of ZrO_2 Crystalline Phase on the Performance of Ni-B/ZrO_2 Catalyst for the CO Selective Methanation

Amorphous Ni-B/ZrO2 catalysts were prepared by coprecipitation-chemical reduction with KBH4 aqueous solution,and various crystalline phase ZrO2(amorphous-ZrO2,tetragonal-ZrO2 and monoclinic-ZrO2) supported Ni-B catalysts were obtained by thermal treatment in 5%H2-N2 stream at different temperature.The effect of ZrO2 polymorphs and the treatment temperature on the catalytic performance for the CO selective methanation were investigated,and the catalysts were characterized by N2 physisorption,Powder X-ray diffraction(XRD), Temperature-Programmed Desorption(CO-TPD and H2-TPD),and Differential Scanning Calorimeter(DSC).The treatment temperature affected strongly the crystalline structure of ZrO2,and the CO methanation activity and selectivity of the Ni-B/ZrO2 catalysts were significantly influenced by the crystalline phase of ZrO2.Of the three forms of ZrO2 polymorphs(amorphou-ZrO2,tetragonal-ZrO2 and monoclinic-ZrO2),the amorphous-ZrO2 supported nickle catalyst showed highest CO methanation activity,attributing in large part to the largest specific surface area and the optimum CO/H2 absorption intensity of the Ni-B/amorphous-ZrO2 catalyst.

Laser additive manufacturing of Si/ZrO_(2)tunable crystalline phase 3D nanostructures

The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials with subsequent heat treatment leading to a variety of crystalline phases in 3D structures.In this work,it was examined a series of organometallic polymer precursors with different silicon(Si)and zirconium(Zr)molar ratios,ranging from 9:1 to 5:5,prepared via sol-gel method.All mixtures were examined for perspective to be used in 3D laser manufacturing by fabricating nano-and micro-feature sized structures.Their spatial downscaling and surface morphology were evaluated depending on chemical composition and crystallographic phase.The appearance of a crystalline phase was proven using single-crystal X-ray diffraction analysis,which revealed a lower crystallization temperature for microstructures compared to bulk materials.Fabricated 3D objects retained a complex geometry without any distortion after heat treatment up to 1400℃.Under the proper conditions,a wide variety of crystalline phases as well as zircon(ZrSiO_(4)-a highly stable material)can be observed.In addition,the highest new record of achieved resolution below 60 nm has been reached.The proposed preparation protocol can be used to manufacture micro/nano-devices with high precision and resistance to high temperature and aggressive environment.

The Formula of Dependence of Mechanical Characteristics of Materials on Crystalline Phase Composition in the Matrix

Objective: For materials science and generally, for long-term operation of work-pieces in industry the significant role is attributed to dependence of macro-mechanical properties of consolidated body on crystalline phase composition, its dimensions, form, distribution in matrix and the form factor. While working in responsible fields of technology of ceramics and ceramic composites the above referred properties are attributed extremely great role with the view of durability and endurance at the terms of heavy mechanical loads. For description of the resistance of any concrete type work-piece, the crystalline phase plays the greatest role in mechanical strength or deformation of any material. It plays the important role in correlative explanation of materials mechanics and matrix properties. In our case, in the process of destruction of ceramic materials and composites, which will give us exhaustive response to the role of macro- and micro-mechanical properties of materials, the role of a macro- and micro-structural component, that is, of crystalline phase in the process of transition of stable state of materials into meta-stable state is extremely big. Our study aims to develop a formula of dependence of macro-mechanical properties of ceramic and ceramic composites on crystalline phase, the most powerful component of their structure, which will enable theorists and practitioners to select and develop technologies and technological processes correctly. Method: On the basis of the study of micro- and macro-mechanical properties of ceramics and ceramic composites and the morphology of crystalline phase and the analysis of the study we determined and created parameters of the formula. Results: The formula covers macro-mechanical properties, that is when the work-piece is thoroughly destructed: mechanic at bending at three and four-point load, mechanic at contraction;among morphological characteristics: composition of crystalline phase and their spreading in matrix, their sizes, form factor;correlative dependence of the above listed properties. Absolutely new definition of a factor of spreading of crystalline phase in matrix is offered. Conclusion: The created formula is of consolidated nature and it can be used in technology of any ceramic material and ceramic composites. The formula will help practitioners to plan correctly and fulfill accurately all positions of technology of production of work-pieces, to carry out the most responsible thermal treatment process of technology of manufacture of work-pieces;to determine correlation between mechanical and matrix properties of materials.

Crystalline structure and morphology of X phase in Cu Al-Ni-Mn-Ti alloy

The composition, morphology, crystalline structure and formation and evolution of X phase in a Cu 12.3Al 2Ni 2Mn 1Ti alloy were studied. The results show that the X phase is a Ti rich phase with atomic ratio of (Cu+Ni)∶ Ti∶Al=2∶1∶1 and DO 3 or L2 1 structure; it is directly formed in the liquid phase by crystallization in the process of solidification of the alloy; there forms free particle X phase through the progressive dissolution and breakdown of the inter dendritic microstructure in the following homogenization process. The X phase has three different morphologies, i.e. X L, X LS and X S, whose contents in the matrix rely on the heat treatment conditions. [

Cure reaction and phase behavior of liquid crystalline epoxides-anhydride systems

A series of novel liquid crystalline epoxides with lateral substituents were cured with anhydrides and the cure kinetics was investigated by non-isothermal DSC technique. The results showed that the lengths of lateral substituents have great effect on the value of Ea. The curing reaction became less active, when the liquid crystalline epoxides have long lateral substituents and were controlled by diffusion at the late stage of cure. A nematic structure was observed by POM and XRD.

Phase field modeling of the ring-banded spherulites of crystalline polymers: The role of thermal diffusion

The ring-banded spherulite is a special morphology of polymer crystals and has attracted considerable attention over recent decades. In this study, a new phase field model with polymer characteristics is established to investigate the emergence and formation mechanism of the ring-banded spherulites of crystalline polymers. The model consists of a nonconserved phase field representing the phase transition and a temperature field describing the diffusion of the released latent heat. The corresponding model parameters can be obtained from experimentally accessible material parameters.Two-dimensional calculations are carried out for the ring-banded spherulitic growth of polyethylene film under a series of crystallization temperatures. The results of these calculations demonstrate that the formation of ring-banded spherulites can be triggered by the self-generated thermal field. Moreover, some temperature-dependent characteristics of the ring-banded spherulites observed in experiments are reproduced by simulations, which may help to study the effects of crystallization temperature on the ring-banded structures.

PHASE STRUCTURE AND THERMAL BEHAVIOR OF LIQUID CRYSTALLINE MULTI-BLOCK COPOLYMERS,POLY[1,6-BIS(4-OXYBENZOYL-OXY)HEXANE TEREPHTHALATE]-b-BISPHENOL A POLYCARBONATE

Liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segments of polycarbonate (PC) and thermotropic polyester PHTH-6 were synthesized in tetrachloroethane at 144 similar to 146 degrees C. The influence of segment length on the resulting phase structure and thermal behavior of block copolymers was also discussed. It is demonstrated by TEM and DMA that the resulting block copolymers show a considerable microphase separation. The degree of phase separation and the thermal behavior of the block copolymers are strongly dependent on the molecular weight of the segments incorporated.

Influence of substituting B_(2)O_(3) with Li_(2)O on the viscosity,structure and crystalline phase of low-reactivity mold flux

The low-reactivity mold flux with low SiO_(2)content is considered suitable for the continuous casting of high-aluminum steel since it can significantly reduce the reaction between Al in steel and SiO_(2)in mold flux.However,the traditional low-reactivity mold flux still presents some problems such as high viscosity and strong crystallization tendency.In this study,the co-addition of Li_(2)O and B_(2)O_(3)in CaO–Al_(2)O_(3)–10wt%Si O_(2)based low-reactivity mold flux was proposed to improve properties of mold flux for high-aluminum steel,and the effect of Li_(2)O replacing B_(2)O_(3)on properties of mold flux was investigated.The viscosity of the mold flux with 2wt%Li_(2)O and 6wt%B_(2)O_(3)reached a minimum value of 0.07 Pa·s.The break temperature and melting point showed a similar trend with the viscosity.Besides,the melt structure and precipitation of the crystalline phase were studied using Raman and X-ray diffraction spectra to better understand the evolution of viscosity.It demonstrated that with increasing Li_(2)O content in the mold flux from 0 to 6 wt%,the degree of polymerization of aluminate and the aluminosilicate network structure increased because of increasing Li+released by Li_(2)O,indicating the added Li_(2)O was preferentially associated with Al^(3+)as a charge compensator.The precipitation of LiAlO_(2)crystalline phase gradually increased with the replacement of B_(2)O_(3)by Li_(2)O.Therefore,Li_(2)O content should be controlled below 2wt%to avoid LiAlO_(2)precipitation,which was harmful to the continuous casting of highaluminum steels.

Ultra-fast phosphating synthesis of metastable crystalline phase-controllable ultra-small MPX/CNT(M = Pd, Pt, Ru) for polyalcohol electrooxidation

A general approach is reported for ultra-fast phosphating synthesis of a series of ultra-small(<5 nm)noble metal phosphides(MPX/CNT,M=Pd,Pt,Ru)which are successfully produced in just 75 s for the first time.The catalytic performance of the catalysts can be optimized by controlling the nanomaterials as the metastable crystalline phases.By altering the phosphorus source under the same conditions,the hexagonal structured Pd_(7)P_(3)(NaH_(2)PO_(2).H_(2)O as P source)and monoclinic structured Pd_(6)P(Na_(4)P_(2)O_(7) as P source)can be prepared successfully.Both of them exhibit excellent polyol oxidation performance in alkaline media.Monoclinic Pd_(6)P/CNT and hexagonal Pd_(7)P_(3)/CNT have large ECSA which are confirmed as 82.1 m2 g^(-1)and 86.2 m2 g^(-1),respectively.Hexagonal Pd_(7)P_(3)/CNT has the highest mass activity of 6.14 A mgPd^(-1)(3.21 A mgPd^(-1)for Pd_(6)P/CNT)for GOR,which far exceeded Pt/C(2.81 A mgPt^(-1)).Meanwhile,the mass activity of monoclinic Pt_(5)P_(2)/CNT for EGOR achieved 12.4 A mg_(Pt)^(-1),which far exceeded Pt/C(6.8 A mg_(Pt)^(-1)).The stability test proved that the activity decay of these catalysts was negligible after the 12-hour durability test.Meanwhile,they have excellent CO anti-poisoning abilities.

QUASICRYSTALLINE AND CRYSTALLINE PHASES IN RAPIDLY SOLIDIFIED Al33Cu10Fe24Ti33 ALLOY POWDERS

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Atomic-Ordering-Induced Quantum Phase Transition between Topological Crystalline Insulator and Z_2 Topological Insulator

Topological phase transition in a single material usually refers to transitions between a trivial band insulator and a topological Dirac phase, and the transition may also occur between different classes of topological Dirac phases.It is a fundamental challenge to realize quantum transition between Z_2 nontrivial topological insulator（TI） and topological crystalline insulator（TCI） in one material because Z_2 TI and TCI have different requirements on the number of band inversions. The Z_2 TIs must have an odd number of band inversions over all the time-reversal invariant momenta, whereas the newly discovered TCIs, as a distinct class of the topological Dirac materials protected by the underlying crystalline symmetry, owns an even number of band inversions. Taking PbSnTe_2 alloy as an example, here we demonstrate that the atomic-ordering is an effective way to tune the symmetry of the alloy so that we can electrically switch between TCI phase and Z_2 TI phase in a single material. Our results suggest that the atomic-ordering provides a new platform towards the realization of reversibly switching between different topological phases to explore novel applications.

Evaluation of Non Crystalline Phase in AZS Refractories by XRD Methods

The relation between the atomic structure and the macroscopic properties and behaviors of a material constitute one of the objectives of the materials science, particularly in the design and development of ceramic materials.Crystalline and non crystalline phases together with pores, grain boundaries, etc. affect mechanical and fracture properties as well as chemical resistance and electric properties. These aspects will be bonded to the raw materials chosen and the whole processing route.In glass industry, although there are other electrofused refractories such as the alumina ones used in the feeding of the fusion kilns, probably the most used refractories in contact with the melted glass are electrofused materials that belong to the Al2O3-SiO2-ZrO2 system commonly named AZS.Exceptionally for refractory materials the amount of the glassy phase in a AZS material is important and appreciable;and makes them particularly adequate for containing fussed glass. The glass proportion will define much of their properties and behaviors.In the present work the results of the non crystalline phase quantification of two samples of commercial AZS materials are presented and compared. These were obtained by three different methods using in the X ray powder diffraction (XRD) techniques. The first method consists in the linear interpolation of the base lines of the diffractograms compared to the amorphous silica and the fully crystalline quartz. The other two methods are based in the application of the Rietveld method. One is the internal standard method with quartz as fully crystalline standard and the other one consist in the inclusion of the glassy phase to the refinement with a structural model that can be understood as the widening of the peaks consequence of an extreme decrease in the crystallite size of a quartz phase.The three methods showed equivalent results (with differences less than 3%) for the two samples and demonstrated that are adequate for the quantification of the non crystalline phase in this kind of materials.

SYNTHESIS AND PHASE BEHAVIOR OF LIQUID CRYSTALLINE 4'-ALKYLOXY-4-HYDROXYBIPHENYLS

The synthesis and phase behavior of a series of 4'-alkyloxy -4-hydroxy biphenyls were discribed.The effects of reaction conditions on the yields of products were investigated.The characterizations of thermotropic liquid crystalline products for the type and thermal properties are discussed through the use of differential scanning calorimetry,polarizing microscopy.

MULTIPLE MELTING BEHAVIOR OF β-CRYSTALLINE PHASE POLYPROPYLENE

Differential scanning calorimetry and X-ray diffraction experiments on β-nucleated polypropylene were made on the samples crystallized at different temperatures and processed by injection molding. The crystal perfection was shown to vary with crystallization temperature. The observed multiple peaks could be related to a ill-phase with defective inclination of the chains, a recrystallized or original β_2-phase of more perfect inclination, and the α-phase. Injection molded samples could be analyzed from the established DSC interpretation.

Determination of Particle Sizes and Crystalline Phases on Colloidal Silicon Nanoparticle Suspensions

Particle size and crystallinity of silicon nanoparticles were determined by analyzing the optical extinction spectra of colloidal suspensions. Experimental results from these colloids were anaiyzed using Mie theory in connection with effective medium theory, in order to determine particle sizes and their internal structure with the simple technique of optical transmission spectroscopy. By modeling an effective refractive index for the particles, the crystalline volume fraction can be extracted from extinction spectra in addition to information about the size. The crystalline volume fraction determined in this way were used to calibrate the ratio of the Raman cross sections for nanocrystalline and amorphous silicon, which was found to be σc./σa = 0.66