Thickness Of Crystalline Layer Research Articles

Sintering and crystallization kinetics of bioactive glass 13–93

This study investigates the sintering and crystallization behavior and kinetic of the bioactive glass (BG) 13–93 with nominal composition (in mol%): 54.6 SiO2 - 1.7 P2O3 - 22.1 CaO - 6.0 Na2O - 7.9 K2O - 7.7 MgO. Sintering and crystallization were investigated non-isothermally for various particle size fractions smaller than 315 µm as well as for bulk samples. Densification was not hindered by the presence of crystalline phases across all particle size fractions. Afterwards, wollastonite was found as the dominant crystal phase at higher temperature which resorb primary surface precipitation-like quartz crystallites. The growth direction shifts into volume when the sample surface is nearly covered. The crystal growth rate of wollastonite was calculated from the crystalline surface layer thickness measured during heating. The findings of this study are relevant for the high temperature processing of BG 13–93.

Effects of erythritol on rheological properties of rice flour and structural characteristics of extruded dried rice noodles with rapid rehydration behaviors

Dry rice noodles are associated with difficulties in rehydration and high cooking losses. The aim of this research was to improve the rehydration and edible quality of dried rice noodles by adding erythritol, a natural sweetener. Results from water contact angle (WCA), X-ray diffraction (XRD), small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and other indicators indicated that erythritol significantly decreased the water contact angle, crystallization degree, crystalline layer thickness, and enthalpy of gelatinization of dried rice noodles while loosening their network structure. The addition of 20% (w/w) erythritol greatly enhanced the rehydration and edible quality of dried rice noodles. Compared with the unmodified control group, the rehydration time, cooking losses, and cooking breakage rate were reduced by 43.61%, 22.45%, and 91.78%, respectively. Besides, the tensile strain, chewing hardness and toughness increased by 44.34%, 102.90%, and 66.89%, respectively. All the results confirmed that the addition of erythritol is an effective method for producing high-quality dried rice noodles.

Effect of Lactiplantibacillus plantarum and Saccharomyces cerevisiae fermentation on the multi-scale structure and physicochemical properties of highland barley starch

Modified starch was better suitable for food processing, and fermentation was one of the effective methods to modify starch. This study investigated the separate and synergistic fermentation of Lactiplantibacillus plantarum and Saccharomyces cerevisiae could whether affect the multi-scale structure and physicochemical properties of highland barley starch (HBS). The results of multi-scale structure determination of HBS showed that compared with unfermented HBS (32.27%), fermentation showed a significant increase in relative crystallinity (35.49–39.81%), while the crystal type of HBS as observed from X-ray diffraction (A-type crystalline pattern) did not change. The small angle X-ray scattering revealed that fermentation reduced the amorphous region and increased the crystalline layer thickness of the HBS. Consequently, the changes in the physicochemical properties showed that the peak viscosity, trough viscosity, and final viscosity of HBS were reduced after fermentation, and the aging of starch gel was delayed significantly. Our results showed that Lactiplantibacillus plantarum and Saccharomyces cerevisiae fermentations improve the physicochemical properties of HBS by modifying the multi-scale structure of starch, especially the synergistic fermentation effect was more effective.

Plastic Deformation of High Density Polyethylene with Extended-Chain Crystal Morphology.

Samples of polyethylene with extended-chain crystal morphology, obtained by crystallization under high pressure, were subjected to uniaxial compression to various strains. Accompanying structural changes were analyzed using scanning electron microscopy. At the true strain of e = 0.2−0.3 the microbuckling instability was observed in longitudinally loaded lamellae, resulting in the formation of angular kinks. This induced a rapid reorientation of the lamellae, facilitating their further deformation by crystallographic slip. Microbuckling instability was found to occur earlier than in samples with folded-chain crystal morphology (e = 0.3−0.4) due to a smaller ratio of the amorphous to crystalline layer thickness. SEM observations demonstrated that the microbuckling instability begins with small undulation in long lamellae. Sharp angular lamellar kinks develop from the initial undulation through intense plastic deformation by crystallographic slip along the chain direction. The same slip system was found to operate throughout the kink, including the tip region as well as both limbs. In contrast to thin folded-chain lamellae that often undergo fragmentation during deformation, the thick extended-chain lamellae deform stably by chain slip and retain their continuity up to high strains, e > 1.6. This stability of deformation is related to the large thickness of extended-chain lamellae.

Nonlinear Quantum Phenomena During the Polarization of Nanometer Layers of Proton Semiconductors and Dielectrics

This paper investigates the influence of the structure and parameters of the degenerate quasi-discrete energy spectrum of relaxers (protons) on the mechanism of nonlinear quantum diffusion polarization in nanoscale layers of hydrogen bonded crystals (HBC) in a wide range of parameters of fields (100 kV/m - 1000 MV/m) and temperatures (0-1550 K). The temperature dependence of the quantum transparency of the parabolic potential barrier for protons in HBC is calculated using the Gibbs quantum canonical distribution for the ensemble of non-interacting protons (ideal proton gas balanced with the ions of anion sub-lattice) moving in an onedimensional potential field of a crystalline lattice (in the field of hydrogen bonds) with a zone structure distributed by energy levels. The influence of "zero" oscillations of protons on the temperature dependences of the proton subsystem kinetic coefficients in HBC is considered. It is revealed that proton tunneling influences the nonlinear space-charge polarization kinetics in HBC at high (150-550 K) and ultrahigh (550-1550 K) temperatures when crystalline layer thickness ranges from 1 to 10 nm. The results of theoretical studies (based on earlier experiments) are bound to be prospective for the prediction of HBC-class (KDP, DKDP) ferroelectrics properties, studying the second-order nonlinear optical effects of femtosecond lasers, and the development of memory cells for non-volatile high-speed memory devices.

Impact of superheated steam on the moisture transfer, structural characteristics and rheological properties of wheat starch

Superheated steam treatment (SST) can improve cereal-based foodstuff quality. Starch is the major component of cereal-based foodstuffs, playing a key role in food quality. For understanding the effect of SST on the moisture distribution, lamellar structure and molecular weight of wheat starch, the low-field nuclear magnetic resonance (LF-NMR), small angle X-ray scattering (SAXS) and size exclusion chromatography were employed. Compared with native starch, SST reduced the average thickness of crystalline layer and induced the depolymerization of starch molecules, which were attributed to the limited moisture transfer resulting in the partial gelatinization of starch granules. The structural variations had a synergistic effect on the rheological properties of starch samples. Upon SST, treated samples exhibited a weaker pseudoplasticity behavior and increased the deformability and mobility of gels systems. Furthermore, the lower tanδ values of treated starch samples were observed, indicating that the gels systems tended to the solid-like behaviors.

Crystallization mechanisms of cordierite glass-ceramics with “surface-center” crystallization behavior

Cordierite glass-ceramics usually begin to crystallize from the surface. As an efficient nucleating agent, TiO2 can promote the rapid transformation of glass to bulk crystallization, but it is easy to cause the increase of dielectric constant and light absorption. High crystallinity cordierite glass-ceramics were prepared by optimizing the heat treatment process without or with different nucleating agents in stoichiometric cordierite glasses. The results show that the crystallization mechanisms of glasses without and with ZrO2+P2O5 as nucleation agents are controlled by surface crystallization. While, the glass with TiO2+ZrO2+P2O5 as nucleation agents have the tendency to be bulk crystallization. The studied glasses are crystallized from surface and have different crystallization orientations with the inner glass. The thickness of crystalline layer increased with the increasing of heating temperatures, but the “surface-center” crystallization process cannot complete by further increasing heating temperatures because of softening deformation of glasses. At 1020 ℃, the glasses complete the “surface-center” crystallization for long durations. The glasses without nucleation agents and with ZrO2+P2O5 require 10 h, but the glass with TiO2+ZrO2+P2O5 complete for 5 h. Although all the three glasses complete the “surface-center” crystallization, the glasses with nucleation agents show the higher crystallinity upon the same heat treatments. Finally, glass-ceramics with excellent performance were obtained, for example, the Z1# glass-ceramic have the high microhardness ∼7.4 GPa, low thermal expansion coefficient ∼1.4☓10−6 ℃−1 at 20–300 ℃, and relatively high thermal conductivity ∼2.4 W/mK. It also exhibits low dielectric constant and loss, which was ∼4.5 and ∼1.2☓10−3 at 1 MHz, ∼ 4.9 and 2.3☓10−3 at 10.5 GHz..

Effect of the crystalline layer on the electrical behaviour of 17.7Li2O·5.2ZrO2·68.1SiO2·9.0Al2O3 glass ceramic monoliths

Li2O–ZrO2–SiO2–Al2O3 (LZSA) glass ceramic systems are usually obtained from powder technology to obtain materials with a low thermal expansion coefficient (CTE). However, in these cases, there is a high residual porosity. An alternative to reduce the porosity involves the production of monoliths. Nevertheless, there is still a lack of crystallisation kinetics and the final properties of glass ceramic monoliths are affected such as electrical properties. This study aims to evaluate the electrical behaviour as function of the crystalline layer thickness formed on the monolith surface of a 17.7Li2O·5.2ZrO2·68.1SiO2·9.0Al2O3 (molar basis) glass ceramic LZSA composition. Monoliths thermally treated at 750, 800, and 850 °C were chosen to evaluate based on the range of the crystalline layer growth. Electrochemical impedance spectroscopy was used for the electrical characterisation of LZSA glass and the glass ceramics. The resistivity increased with increasing thermal treatment temperature due to the formation of lithium-based crystalline phases. The electrical conductivity at 25 °C of the glass ceramic thermally treated at 850 °C decreased to 1.4 × 10−13 S cm−1 from 8.7 × 10−11 S cm−1 for LZSA glass. Based on the electrical behaviour, monoliths thermally treated at 850 °C can be considered potential for dielectric industrial applications.

Highly reinforcing effect of polycarbonate/poly(ethylene terephthalate) blends by formation of orientation microfibrillar structure

AbstractHighly oriented microfibrillar polycarbonate/poly(ethylene terephthalate) (PC/PET) blends were prepared. Before orientation, the molecular chains of the blends were mostly randomly arranged with a low crystallinity, and low mechanical properties were obtained. Under stress, it was difficult for molecular chains of the amorphous PC phase in blends to form an oriented crystalline structure. With increasing draw ratio, the crystallinity and orientation degree of the PET phase increased, forming a dense lamellar structure with reduced crystalline and amorphous layer thickness, while with increasing PET content the crystalline orientation degree of the PET phase increased with larger sized lamellae. Moreover, the cross‐section of the oriented sample showed an obvious ordered microfibrillar bundle structure, which arranged compactly and orderly along the drawing direction. The tensile strength and modulus of the oriented PC/20 wt% PET sample were up to 126.01 and 7170.10 MPa, which were 66.48% and 317.49% respectively higher than those of pure PC. Therefore, the stress‐induced oriented microfibrillar structure of the PET phase exhibited a highly reinforcing effect on the PC phase and the blend. © 2021 Society of Industrial Chemistry.

Design and fabrication of lutetium aluminum silicate glass and nanostructured glass for radiation detection

AbstractFlexible scintillating fiber plays an important role in X‐ray radiation monitoring and high‐resolution medical imaging, while construction of scintillating fiber derived from the commercial material system meet with limited success. Here, we report the design and successful fabrication of the Ce‐activated lutetium aluminum silicate glass, nanostructured glass, and fiber, and explore their scintillating properties. The scintillating glass with optimized composition and optical properties is determined. The crystallization behavior of lutetium aluminum silicate glass is studied and the nanostructured glass embedded with orthorhombic Lu2Si2O7 phase is successfully constructed for the first time. Importantly, the crystalline layer thickness of the nanostructured glass can be finely tuned and ~172.89% enhancement in the scintillating performance can be achieved. Furthermore, the fiber with large sized core is fabricated and its radiation response properties are tested. The results show that it exhibits high sensitivity and its scintillating emission is lineally dependent on the X‐ray power, indicating the potential application for radiation detection.

Experimental investigation and numerical simulation of the microinjection molding process through an expanding flow configuration

The dependence of the induced morphological layer variations on the processing conditions and parameters during injection molding of polymers is analyzed through a robust numerical framework of the complete microinjection molding cycle. Predicted temperature, heat transfer and viscous dissipation, spherulite diameters, and shear rates provide sufficient clarifications to develop a deeper understanding of the complex evolution of the induced thicknesses of layers. The evolution of the structure of polyoxymethylene (POM) under strong strain rates and high thermal gradients is investigated while flowing along an expanding flow configuration composed of three steps of increasing thickness. High and low mold temperatures and injection velocity levels are tested according to the design of the experiment method (DOE). Morphological development in each zone was examined to provide the induced crystalline layer thickness in the longitudinal as well as the transverse directions using polarized light microscopy (PLM). The thickness of the layers strongly depends on the local thickness of the stepped‐part and on the abrupt dimensional changes. The variation of bulk tensile properties obtained by dynamic mechanical analysis (DMA) is related to the thermomechanical history experienced by the melt.

Few-Layer In2S3 in Laponite Interlayers: A Colloidal Route Toward Heterostructured Nanohybrids with Enhanced Photocatalysis

2D nanomaterials are emerging rapidly because of their exceptional chemical and physical properties. Reducing the thickness or number of crystalline layers improves the catalytic performance of man...

A Generic Shear Wave Velocity Profiling Model for Use in Ground Motion Simulation

This study presents a generic model for constructing shear-wave velocity (VS) profiles for various conditions that can be used for modeling the upper-crustal modification effects in ground motion simulations for seismic hazard analysis. The piecewise P-wave velocity (VP) profiling model is adopted in the first place, and the VS profile model is obtained by combining the VP profiling model and VS/VP model. The used VS/VP model is constructed from various field measurements, experimental data, or CRUST1.0 data collected worldwide. By making the best use of the regionally/locally geological information, including the thickness of sedimentary and crystalline layers and reference VS values at specific depths, the VS profile can be constructed, and thus the amplification behavior of VS for a given earthquake scenario can be predicted. The generic model has been validated by four case studies of different target regions world around. The constructed profiles are found to be in fair agreement with field recordings. The frequency-dependent upper-crustal amplification factors are provided for use in stochastic ground motion simulations for each respective region. The proposed VS profiling model is proposed for region-specific use and can thus make the ground motion predictions to be partially non-ergodic.

Crystal growth of La2SrB10O19 from undercooled melt

The crystal growth rate of La2SrB10O19 in an undercooled melt of stoichiometric composition was studied. The crystallization of the bulk samples was performed in a single-stage regime under isothermal conditions at the selected temperatures for the different time periods. The surface crystallization was observed and in all crystallized samples, the La2SrB10O19 crystalline phase was identified. Based on the dependence of the crystalline layer thickness on treatment time at selected temperature, crystal growth rate was obtained. The crystal growth rates were from 1.65 × 10−8 to 2.77 × 10−7 m s−1 in the temperature interval (700–780 °C). The experimental values were compared to the calculated values using theoretical model of the crystal growth. The experimental growth rate followed the same trend as the calculated growth rate, but the experimental values were higher than the calculated.

Anisotropic deformation behaviors of amorphous-crystalline nanolaminates investigated via molecular dynamics simulations

Amorphous-crystalline nanolaminates (ACNLs) composed of CuZr metallic glass layers and single crystal copper layers were constructed, and the anisotropy of the material deformation behaviors were investigated by conducting shear loadings on the ACNL sample in parallel deforming and serial deforming directions using molecular dynamics method. In parallel deforming mode, the yielding of the material was mainly triggered by generation of dislocations and slips in crystalline layer, and both crystalline and amorphous phases participated in the subsequent plastic deforming. In serial deforming mode, the results showed that the yielding and plastic deforming of the material was induced by shear localization of amorphous layers only. Amorphous-crystalline interfaces (ACIs) served as stress resistance weakness and dislocations breeding cradle in the former deforming mode while a strong connection of two phases in the later deforming mode. Furthermore, the increasing of crystalline layer thickness would promote the material shear modulus and shear strength in both deformation modes. The promotions and incentives varied and had dependence on the coupled deforming mechanisms. For the serial deforming mode, the shear moduli obtained from our simulations fitted the predicted ones from rule-of-mixture very well, while in the parallel deforming mode, the simulated shear moduli were much higher than predicted ones, which could be explained with the size effect induced by reduction of crystalline layer thickness surround with ACIs.

Diffractive X-ray Waveguiding Reveals Orthogonal Crystalline Stratification in Conjugated Polymer Thin Films

The depth dependence of crystalline structure within thin films is critical for many technological applications, but has been impossible to measure directly using common techniques. In this work, by monitoring diffraction peak intensity and location and utilizing the highly angle-dependent waveguiding effects of X-rays near grazing incidence we quantitatively measure the thickness, roughness and orientation of stratified crystalline layers within thin films of a high-performance semiconducting polymer. In particular, this diffractive X-ray waveguiding reveals a self-organized 5-nm-thick crystalline surface layer with crystalline orientation orthogonal to the underlying 65-nm-thick layer. While demonstrated for an organic semiconductor film, this approach is applicable to any thin film material system where stratified crystalline structure and orientation can influence important interfacial processes such as charge injection and field-effect transport.

Molecular dynamics study of deformation behavior of crystalline Cu/amorphous Cu50Zr50 nanolaminates

Crystalline/amorphous (C/A) metallic nanolaminates have been increasingly studied due to its excellent mechanical behaviors. Here, the effects of layer thickness and sample size on the deformation behavior of C/A Cu/CuZr nanolaminates under tension loading are investigated using molecular dynamics simulation method. For nanolaminates with equal layer thickness of crystalline and amorphous, a transition in the plastic deformation mode takes place in the C/A nanolaminates from homogeneous plastic co-deformation between interfacial dislocation and shear transformation zones to multiple shear bands interaction. For the nanolaminates with fixed amorphous layer, the peak stress decreases with the decreasing crystalline layer thickness, consisting with the results calculated by the mixed rule. However, when crystalline layer thickness is >5nm, the peak stress reaches a plateau, which can be well-explained by the confined layer slip model. In addition, the results indicate that the plastic deformation behavior of nanolaminates transits from global plastic deformation to local plastic deformation with decreasing aspect ratio.

Size-dependent hardness and tensile plasticity of Ta-Zr 61 Cu 17.5 Ni 10 Al l7.5 Si 4 nanolaminates

Abstract Ta/Zr 61 Cu 17.5 Ni 10 A l7.5 Si 4 crystalline/amorphous (C/A) nanolaminates with different Ta and ZrCuNiAlSi layer thicknesses were deposited by magnetron sputtering on both Si and polyimide substrates. Nanoindentation and uniaxial tensile tests were separately performed to study their size-dependent hardness and plasticity. Tensile plasticity was evaluated by considering both the tensile cracks and nanoindentation morphologies observed under scanning electron microscope (SEM). C/A nanolaminates with crystalline layer thickness of 40 nm and amorphous layer thickness of 5 nm exhibited the best tensile plasticity, which was much better than pure Ta and Zr 61 Cu 17.5 Ni 10 A l7.5 Si 4 monolayers. For nanolaminates having identical Ta layer thickness, the hardness always increased with decreasing amorphous layer thickness. Combined with cross-sectional high resolution transmission electron microscopy (HRTEM) observation, the size-dependent deformation mechanisms of C/A nanolaminates were discussed.

Plastic deformation behaviors of amorphous-Cu50Zr50/crystalline-Cu nanolaminated structures by molecular dynamics simulations

As promising composites in engineering applications, amorphous/crystalline nanolaminates have attracted great research interests by its excellent mechanical behaviors recently. In this study, plastic deformations of amorphous Cu50Zr50 and amorphous-Cu50Zr50/crystalline-Cu/amorphous-Cu50Zr50 nanolaminated structures with different crystalline layer thickness under pure shear loading were studied using molecular dynamic simulations. A transition in the plastic deformation mode takes place in the nanolaminated structure from the pure shear banding deformation in the amorphous CuZr to the interactive deformation between interfacial dislocation in the crystalline layer and shear transformation zones (STZs) in the amorphous layer. It is found that the partial dislocation sliding, which is activated by local strain concentration in the amorphous at amorphous/crystalline interface, alleviates and releases the large atomic shear strain concentration in the amorphous. As a result, interfacial dislocation-STZs interaction process prevents the evolution of shear localization at the layer interface and facilitates a more homogeneously plastic deformation in the nanolaminated structure. Besides, the dislocation intersection within a large crystalline layer can cause strain hardening, which provides potentials for the combination between high strength and good plastic deformability at the engineering applications.

A Study of the Heat Transfer Behavior of Mold Fluxes with Different Amounts of Al2O3

The element Al in molten aluminum containing steel reacts with the liquid mold flux and thus be transferred into the mold flux during the continuous casting process. Additionally, the increase in alumina in a mold flux changes its performance significantly. Thus, in this paper, the heat transfer properties of mold fluxes with the Al2O3 content ranging from 7 to 40 wt. % were studied with the Infrared Emitter Technique (IET). Results found that heat flux at the final steady state decreased from 423 kW·m−2 to 372 kW·m−2 with the increase in Al2O3 content from 7% to 30%, but it increased to 383 kW·m−2 when the Al2O3 content was further increased to 40%. Both crystalline layer thickness and crystalline fraction first increased, then decreased with the further addition of A2O3 content. Moreover, it indicated that the heat transfer process inside the mold was dominated by both a crystallization of mold flux and the resulting interfacial thermal resistance. Further, the Rint increased from 9.2 × 10−4 m2·kW−1 to 11.0 × 10−4 m2·kW−1 and then to 16.0 × 10−4 m2·kW−1 when the addition of Al2O3 content increased from 7% to 20% and then to 30%, respectively; however, it decreased to 13.6 × 10−4 m2·kW−1 when the Al2O3 content reached 40%.