Final Morphology Research Articles

Morphological evolution mechanism of copper-based azide during gas-solid azidation process: Experiment and thermodynamic analysis

Copper-based azide (CA) synthesized by in-situ gas-solid azidation and utilized as preferred material for miniaturized explosive systems has attracted extensive attention from researchers. This work aims to reveal the morphological evolution mechanism of CA during gas-solid azidation processes. The morphological evolution processes of CA under different reaction conditions were observed and corresponding reaction stages were divided by the characteristics of product morphology. The morphology of product islands possesses a significant impact on the final morphology. To further reveal the morphological evolution mechanism, the continuous product layer and product islands core-shell thermodynamic equilibrium models were derived and studied to explain experimental findings. The energy properties of Cu(111), CuN3(220), Cu(N3)2(110) surfaces and corresponding interfaces were studied by first principle calculation to perform the thermodynamic equilibrium analysis. Based on the calculation results, the equilibrium thermodynamics analysis of Cu-CuN3, Cu-Cu(N3)2 and CuN3-Cu(N3)2 core-shell systems were performed and the corresponding dependence was discussed. The reaction modes were divided into thermodynamic-dominated and kinetic-dominated modes based on the different orders of product generation and the results of thermodynamic equilibrium analysis. The morphological evolution mechanism was proposed based on thermodynamic analysis and different reaction modes, which provides a fundamental perspective to regulate CA morphology and enhance corresponding performance.

The Effects of the Pre-Anodized Film Thickness on Growth Mechanism of Plasma Electrolytic Oxidation Coatings on the 1060 Al Substrate.

To increase the density of the micro-arc oxide coating, AA 1060 samples were pretreated with an anodic oxide film in an oxalic acid solution. Plasma electrolytic oxidation (PEO) was performed to investigate the effect of the thickness of the pre-anodic oxide film on the soft-sparking mechanism. The experimental results revealed that the PEO coating phases with different thicknesses of the pre-anodized films contained both Al and gamma-alumina (γ-Al2O3). The pre-anodized film changes the final morphology of the coating, accelerating the soft sparking transition and retaining the soft sparking. At a pre-anodized film thickness of ≤7.7 μm, the anodized films thickened before being broken through. When the pre-anodized film thickness was ≥13.1 μm, partial dissolution of the anodized films occurred before they were struck through. Two growth mechanisms for PEO coatings with different pre-anodized film thicknesses were proposed.

(Invited) Delineating the Intricacies Involved in the Synthesis of Cobalt-Free High-Nickel Layered Oxide Cathodes for Lithium-Ion Batteries

Improving the energy density and cost of lithium-ion batteries (LIBs) requires a rational compositional design of layered oxide LiNi1-x-yMnxCoyO2 (NMC) cathodes. The prevailing trend is to increase the nickel content in the cathode to maximize energy density, but high-nickel NMC generally suffers from surface and bulk instabilities that shorten battery life. Dopants, such as cobalt, can help mitigate these issues, but its supply shortage issue prohibits its usage especially in the massive electric vehicle market. Our recent finding suggests that a combination of manganese and aluminum in LiNi0.9Mn0.05Al0.05O2 (NMA-90) promotes attractive energy density, cycle life, rate capability and thermal stability, proving that cobalt can be eliminated in high-nickel cathodes. Post-mortem analysis further reveals that the Mn-Al combination provides synergistic improvements in structural and surface stabilities compared to LiNi0.9Mn0.05Co0.05O2 (NMC-90) and LiNi0.9Co0.05Al0.05O2 (NCA-90). A thorough understanding of the relationship between the synthesis condition and optimal materials properties of NMA-90 is necessary to enable its large-scale deployment. We will present findings from the calcination and coprecipitation study of several cobalt-free cathodes to elucidate this relationship. It is revealed that the cycle stability of LiNi0.9Mn0.1O2 (NM-90) is not dependent on Li/Ni mixing or primary particle size, but is dependent on the calcination temperature. Incorporating Al into NM-90 during coprecipitation reactions cause high internal porosity in the hydroxide precursor, which impacts the final morphology of the calcined cathodes and thus their electrochemical stability. The ongoing work in our lab provides insight on the synthesis sensitivity of NMA and strategizes methods to control its electrochemical properties.

Towards High Capacitive Performance of Chemically Deposited β-Ni(OH)2 Nanolamellae Electrode Films.

Nickel hydroxide β-Ni(OH)2 nanolamellae with high aspect ratios were grown via chemical bath deposition (CBD) on both smooth and textured nickel foil. Depending on bath composition and/or the presence of an additive, thin foam-like nanolamellae to stacked lamellae were obtained. The used CBD method is highly cost-effective, as it is faster and requires less chemicals than typical hydrothermal methods, and it is readily implementable for large-scale production. The influence of surface texture on the final morphology and its effect on capacitive performance was investigated. Herein, we show how subtle changes in the concentration can drastically influence the morphology, which, in turn, drastically impacts the supercapacitive performance of the electrode. Also, the use of a textured surface significantly impacts the morphology, with vastly better cycling performance than samples made on a relatively smooth substrate. The measured specific capacitance values of the best sample were 1961 Fg-1 at 5 mVs-1 and 1998 Fg-1 at 1 Ag-1 under potentiostatic and galvanostatic conditions, respectively. This sample also retained 100% of its initial specific capacitance when discharged at a very high current density of 40 Ag-1. These values are substantially enhanced compared to previously reported data using a nearly analogous method (CBD with higher reagent conc.), with our method, cost-wise, offering economic advantages relative to results obtained with similar materials and other methods (e.g., hydrothermal).

Nanocomposite Nanofibers of Graphene—Fundamentals and Systematic Developments

Research on polymer nanocomposite nanofibers has seen remarkable growth over the past several years. One of the main driving forces for this progress is the increasing applicability of polymer nanocomposite nanofibers for technological applications. This review basically aims to present the current state of manufacturing polymer/graphene nanofiber nanocomposites, using appropriate techniques. Consequently, various conducting and thermoplastic polymers have been processed with graphene nano-reinforcement to fabricate the nanocomposite nanofibers. Moreover, numerous methods have been adopted for the fabrication of polymer/graphene nanocomposites and nanofibers including interfacial polymerization, phase separation, freeze drying, template synthesis, drawing techniques, etc. For the formation of polymer/graphene nanocomposite nanofibers, electrospinning can be preferable due to various advantages such as the need for simple equipment, control over morphology, and superior properties of the obtained material. The techniques such as solution processing, melt spinning, and spin coating have also been used to manufacture nanofibers. Here, the choice of manufacturing techniques and parameters affects the final nanofiber morphology, texture, and properties. The manufactured nanocomposite nanofibers have been examined for exceptional structural, microstructure, thermal, and other physical properties. Moreover, the properties of polymer/graphene nanofiber rely on the graphene content, dispersion, and matrix–nanofiller interactions. The potential of polymer/graphene nanocomposite nanofibers has been investigated for radiation shielding, supercapacitors, membranes, and the biomedical field. Hence, this review explains the literature-driven significance of incorporating graphene in polymeric nanofibers. Conclusively, most of the studies focused on the electrospinning technique to design polymer/graphene nanofibers. Future research in this field may lead to advanced innovations in the design and technical applications of nanocomposite nanofibers. To the best of our knowledge, research reports are available on this topic; however, the stated literature is not in a compiled and updated form. Therefore, field researchers may encounter challenges in achieving future advancements in the area of graphene-based nanocomposite nanofibers without first consulting the recent literature, such as an assembled review, to gain necessary insights, etc. Consequently, this state-of-the-art review explores the manufacturing, properties, and potential of polymer/graphene nanocomposite nanofibers.

Rational control of meniscus-guided coating for organic photovoltaics.

Meniscus-guided coating exhibiting outstanding depositing accuracy, functional diversity, and operating convenience is widely used in printing process of photovoltaic electronics. However, current studies about hydrodynamic behaviors of bulk heterojunction ink are still superficial, and the key dynamic parameter dominating film formation is still not found. Here, we establish the principle of accurately evaluate the Hamaker constant and reveal the critical effect of precursor film length in determining flow evolution, the polymer aggregation, and final morphology. A shorter precursor film is beneficial to restraining chain relaxation, enhancing molecular orientation and mobility. On the basis of our precursor film-length prediction method proposed in this work, the optimal coating speed can be accurately traced. Last, a 18.39% power conversion efficiency has been achieved in 3-cm2 cell based on bulk heterojunction fabricated by blade coating, which shows few reduce from 19.40% in a 0.04-cm2 cell based on spin coating.

Morphology evolution of electrodeposited lithium on metal substrates

Lithium (Li) metal is deemed to be the high-energy-density anode material for next generation batteries, but its practical application is impeded by the uneven electrodeposition during charge of battery, which leads to the low Coulombic efficiency and potential safety issue. Here, multiscale modeling is fabricated to understand the morphology evolution of Li during electrodeposition process, from the self-diffusion of Li adatoms on electrode surface, to the nucleation process, and to the formation of Li microstructures, revealing the correlation between final morphology and deposition substrates. Energy batteries and self-diffusion of Li adatom on various substrates (lithium, copper, nickel, magnesium, and silver) result in the different nucleation size, which is calculated by kinetic Monte Carlo simulation based on classical nucleation theory. Formation of Li substructures that are grown from Li nuclei, is revealed by phase field modeling coupled with cellular automaton method. Our results show that larger Li nuclei is obtained under faster self-diffusion of Li adatom, leading to the low aspect ratio of Li substructures and the subsequent morphology evolution of electrodeposited Li. Furthermore, the electrodeposition of Li is strongly regulated by the selection of substrates, giving the practical guideline of anode design in rechargeable Li metal batteries. It is worthy to mention that this method to investigate the electro-crystallization process involving nucleation and growth can be transplanted to the other metallic anode, such as sodium, potassium, zinc, magnesium, calcium and the like.

Microfluidic platform for coupled studies of freezing behavior and final effloresced particle morphology in Snomax ® containing aqueous droplets

Microfluidic platform for coupled studies of freezing behavior and final effloresced particle morphology in Snomax ^® containing aqueous droplets

Fabrication of multisymmetrical hierarchical structures by direct laser interference patterning with 2 beams

A novel method based on Direct Laser Interference Patterning with 2 beams allowing to pattern surfaces with 2 dimensional periodicity and presenting several symmetry axes has been developped. It consists in the picoseond laser writing of the same 1D pattern for different sample orientations. The resulting final morphology depends on the rotation angle between the patterning steps and the number of scans. This way, various 2D short and long range periodic structures can be obtained. We show that by increasing the number of symmetry axes, the sample orientation dependance of the reflectivity, measured at 2 different wavelengths, is reduced, approaching an isotropic behaviour beyond 3 axes. Moreover, as the number of symmetry axes increases, the reflectivity decreases reaching ∼10−3 %, which is explained by the increase of roughness.

Modelling of a Post-Mining Catchment for Future Simulations

Landform evolution modelling (LEM) provides an avenue for simulating how a landscape may evolve over extended time periods of thousands of years. CAESAR-Lisflood LEM which includes a hydrologic model (TOPMODEL) and a hydraulic model (Lisflood) can be used to assess the proposed final landform morphology of a mine site by simulating how the mine landform and the landscape would evolve over a 1000-year period. The accuracy of future simulations depends on the calibration and validation of the model to past and present events. Calibration and validation of the model involve finding a combination of parameters of the model which when applied and simulated gives model outputs similar to those observed for the real site scenario for corresponding input data. Calibrating the sediment output of the CAESAR-Lisflood model at the catchment level and using it for studying the equilibrium conditions of the landform is an area that has yet to be explored. Therefore, the aim of this study was to calibrate the CAESAR-Lisflood model and then validate it. To achieve this, the model was run for a rainfall event with a set of parameters, plus discharge and sediment data for the input point of the catchment, to analyse how similar the model output would behave when compared with the discharge and sediment data for the output point of the catchment. The model parameters were then adjusted until the model closely approximated the real site values of the catchment. The model was then validated by running it for a different set of events and checking that the model gave similar results to the real site values. The outcomes demonstrated that while the model can be calibrated to a greater extent for hydrology (discharge output) throughout the year, sediment output calibration may be slightly improved via the ability to change parameters to take into account the seasonal vegetation growth during the start and end of the wet season. This study is important for designing and testing post-mining rehabilitated landscape systems that assess hydrology and sediment movement in seasonal biomes.

O-121 Temporal development of scores from a time-lapse based artificial intelligence provides no additional benefit compared to the latest score

Abstract Study question Does the temporal development of scores from an artificial intelligence (AI) based embryo selection model provide additional predictive power compared to the latest score? Summary answer Earlier predictions provide no additional predictive power given the latest prediction. Knowing the development of AI scores is thus not beneficial for embryo selection. What is known already Traditionally, embryo grading takes into consideration the final morphology score together with the history of embryo development events. Recent publications have shown that time-lapse based AI models trained on clinical outcomes can automatically rank embryos by the likelihood of implantation that equal or surpass traditional methods, without the necessity for manual evaluation. AI-based methods based on time-lapse data may account for the impact of the full temporal development on likelihood of implantation. In this study, we examine if the addition of previous scores adds to the performance of an embryo selection model. Study design, size, duration A retrospective multicenter study of transferred embryos (n = 2422) with known implantation data (KID) between 2012-2020 from 21 international clinics. Embryos were cultured in EmbryoScope time-lapse incubators for at least 5 days. Both single and multi-embryo transfers in fresh and warmed cycles were included. Embryos were classified as positive (KIDp) or negative (KIDn) by the presence of fetal heartbeat. Implantation likelihood was evaluated at cleavage- and blastocyst stages by a 3D CNN model; iDAScore v2.0. Participants/materials, setting, methods A kernel-based conditional independence test was used to evaluate if a score at x hours post insemination (hpi) provide extra information compared to a score at y hpi. The test estimates the likelihood that a prediction after x hpi does not provide any additional information with regards to predicting KIDp when a prediction after y hpi is available. These likelihoods (p-values) were Bonferroni corrected to adjust for multiple comparisons. Main results and the role of chance KIDp predictions were computed for all embryos at 40, 44, 64, 68, 112, and 116 hpi corresponding to early and median time of transfer for day 2, 3, and 5. For all time points, the conditional independence test showed that there was no added information from knowing predictions at an earlier time point (p > 0.21). Similarly, it was tested if a known later prediction will improve model performance for an earlier prediction. This was always the case (p < 0.01) except for predictions close in time (68 vs 64 hpi; p = 1.0) and (44 vs 40 hpi; p = 1.0). This may reflect that there was little additional embryo development information during a 4-hour period at this development stage. The above shows that knowledge of the temporal score development does not improve model performance compared to using latest available score. This means that an AI model based on time-lapse videos likely considers earlier embryo development events in the context of the entire development history. Limitations, reasons for caution This study is a retrospective study that only looks at AI based on time-lapse videos. There is a potential bias as the embryos were likely of higher quality having been chosen for transfer. It is possible that the results do not generalize to simpler non-3D CNNs. Wider implications of the findings Knowing the temporal score development can introduce subjectivity that might lower implantation rates as the earlier scores were shown to not provide any significant prediction improvement. Trial registration number not applicable

Composition Waves in Solution‐Processed Organic Films and Its Propagations from Kinetically Frozen Surface Mesophases

AbstractOrganic thin films deposited from solution attract wide interest for next‐generation (opto‐)electronic and energy applications. During solvent evaporation, the phase evolution dynamics for different components at different locations are not synchronic within the incrementally concentrated liquid films, determining the final anisotropic morphology and performance. Herein, by examining tens of widely investigated optoelectronic organic films, the general existence of composition wave propagating along the surface‐normal direction upon solidification is identified. The composition wave is initiated by a few nanometers thick surface mesophase kinetically forming at the foremost stage of phase transition, and afterward propagates toward the substrate during solvent evaporation. The composition waves exhibit well‐defined wave properties, including spatial wavelength, period, amplitude, and propagation velocity. These wave properties are closely correlated with the evaporation rate and the diffusion rate of organic molecules, which determines the dynamically varied local composition gradient along the surface‐normal direction. Such composition waves are commonly found for more than 80% of randomly examined solution‐processed thin films for high‐performance organic electronic devices including photovoltaic cells and field‐effect transistors.

Study on Dispersion, Adsorption, and Hydration Effects of Polycarboxylate Superplasticizers with Different Side Chain Structures in Reference Cement and Belite Cement.

To investigate the effects of Reference cement (RC) and Belite cement (LC) systems, different molecular structures of polycarboxylate ether (PCE) were prepared through the free radical polymerization reaction and designated as PC-1 and PC-2. The PCE was characterized and tested using a particle charge detector, gel permeation chromatography, a rotational rheometer, a total organic carbon analyzer, and scanning electron microscopy. The results showed that compared to PC-2, PC-1 exhibited higher charge density and better molecular structure extension, with smaller side-chain molecular weight and molecular volume. PC-1 demonstrated enhanced adsorption capacity in cement, improved initial dispersibility of cement slurry, and a reduction in slurry yield stress of more than 27.8%. LC, with its higher C2S content and smaller specific surface area compared to RC, could decrease the formation of flocculated structures, resulting in a reduction in slurry yield stress of over 57.5% and displaying favorable fluidity in cement slurry. PC-1 had a greater retarding effect on the hydration induction period of cement compared to PC-2. RC, which had a higher C3S content, could adsorb more PCE, leading to a greater retarding effect on the hydration induction period compared to LC. LC and PC-2, on the other hand, exhibited inhibition during the hydration acceleration period. The addition of PCE with different structures did not significantly affect the morphology of hydration products in the later stage, which was consistent with the trend of KD variation. This indicates that the analysis of hydration kinetics can better reflect the final hydration morphology.

Effects of Marine Microalgae on the Developmental Growth of the Sea Urchin Larviculture Anthocidaris crassipina

The sea urchin is a very important aquatic economic organism in many countries and has high food value. However, it has recently been heavily fished, and it would be of great importance to the sustainable development of coral reefs to develop large-scale aquaculture of sea urchins. Sea urchins are prone to death during larval development. Therefore, in this study, three kinds of microalgae were used as the initial food for sea urchins to evaluate whether different kinds of microalgae can improve their survival and growth rates. Chaetoceros muelleri (C), Isochrysis galbana tml (I), and Dunaliella salina (D) were fed to A. crassipina at concentrations of 5000, 10,000, 20,000, and 30,000 cell mL−1. A fasted group was used as control (N). The final body length, final body width, final stomach length, rudiment length, survival rate and morphology were measured to evaluate development and growth. The results showed that feeding with C. muelleri resulted in better growth and survival. After 9 days of feeding with C(20,000 cells mL−1), the rudiment length reached 203.33 ± 12.47 µm. The onset of metamorphosis was observed 12 days post-feeding. The survival rate after feeding C was also significantly higher than that after feeding I and D. In summary, when sea urchins are breeding, it is recommended to choose C(20,000 cells mL−1) or C(30,000 cells mL−1) as the initial feed for larvae to increase the growth and survival of sea urchin seedlings.

Selective Localization of Nanoparticles to Enhance the Properties of PBS/PLA Nanocomposite Blown Films

The addition of nanoparticles could allow to upgrade the performances of biopolymers, making them fit to replace petroleum-based plastics. In order to maximize the sustainability benefits of bio-nanocomposites, it is fundamental to opportunely tune their bulk properties by acting on their nanostructure. In particular, in nanocomposite blends the final morphologies are highly dependent on the selective localization of the nanoparticles: mainly inside one of the polymeric phases and/or at the interface.In this work, nanocomposite PBS (polybutylene succinate)/PLA (polylactic acid) blown films were prepared with the aim of optimizing their mechanical and gas barrier properties by profiting from the multiple functions of nanofillers as reinforcements, compatibilizers and morphology-directors. PBS/PLA blends, at a constant polymers’ weight proportion (80/20), were prepared by twin-screw extrusion, adding a constant amount of a lamellar nanosilicate (Cloisite 30B), according to different mixing routes: (i) by first dispersing the nanofillers inside the PLA or PBS phase, followed by the compounding with the other resin; (ii) by direct mixing of all the three components.The nanocomposite systems showed a finer dispersion of the PLA phase compared to the neat PBS/PLA blend. While a good exfoliation degree of the nanosilicate was generally observed for all the hybrid samples, the different blending sequence of the nanofillers significantly affected their preferential localization. In particular, the barrier and mechanical performances of the hybrid film PBS/(PLA + C30B) were most positively affected by the selective localization of the nanoplatelets at PBS/PLA interface, since their compatibilizing action was effectively exploited. In fact, this latter sample exhibited an interesting increase (+ 29%) of the deformation at break and a significant improvement (+ 33%) of the oxygen barrier compared with the neat PBS/PLA blend.

Morphological Differences of MnS Inclusions in Medium‐Carbon Steel with Different Manganese and Sulfur Contents

The morphology of MnS inclusion is one of the key elements influencing the machinability of steel. Herein, it is shown in the thermodynamic analysis results that the interaction coefficient causes a 1.2% deviation for the precipitation of MnS in low‐sulfur‐content steel (S1), while the deviation is 14% in high‐sulfur steel (S2), and the content of C and Si is the main element causing the deviation. The microstructure of medium‐carbon steel is mainly pearlite and ferrite. The increase of manganese and sulfur content leads to the decrease of ferrite content and increase of pearlite content. Almost all MnS inclusions in S1 are polyhedral, while S2 contains spherelike, cluster, and polyhedral MnS inclusions. Manganese and sulfur mainly affect the nucleation rate of MnS inclusion, where the number density of MnS in S2 is higher than that in S1, which increases the probability of viscous sintering of MnS inclusions in S2, and form spherelike‐ and rodlike‐polycrystalline MnS particles. Polyhedron inclusions are mostly octahedron, and it is the final equilibrium morphology of sulfide in S1 and S2.

Nonclassical and Classical Crystallization: The Formation of Spindle-Shaped CaCO3 Covered with Abundant Nanoscale Rhombic Calcite Subunits

As an essential inorganic material, calcium carbonate (CaCO3) is one of the most abundant minerals in nature, whose preparation by the carbonation of calcium hydroxide [Ca(OH)2] suspension involves complex physical and chemical processes due to the presence of gas–solid–liquid phases. It is challenging to accurately predict the final morphology of CaCO3. In this paper, a novel spindle-shaped CaCO3 covered with a mass of nanoscale rhombic calcite subunits was prepared via the carbonation method. This structure was mainly formed by the aggregation of nanoparticles in the pre-reaction stage and turned into a classical ion–ion growth process at the stage of the late reaction. During the pre-reaction period, solid Ca(OH)2 kept the solution supersaturated and made the aggregation of nanoparticles dominate and assemble to form the nanochains of CaCO3. Subsequently, the aggregation of nanochains formed a dumbbell shape, which was accompanied by the recrystallization of nanoparticles inside aggregates to create an ordered single-crystal spindle structure. Finally, the concentration of Ca(OH)2 decreased, and a layer of nanoscale rhombic calcite subunits grew on the surface of spindle CaCO3. This work will provide new insights into the industrial preparation of CaCO3 with controlled morphology and contribute to understanding the biomineralization of aggregation-based growth in aqueous solutions.

Influence of PMMA brushes grafted from GO on rheological properties of PMMA/SAN immiscible blend in shear and elongation flow

In real technological processes, both shear and elongational flow is present. The material properties may differ significantly under both types of flow. Hence, they both define the final morphology and thus properties of the materials. In this work, the morphology of immiscible blends containing polymer hybrid particles was related to extensional rheological properties for the first time. The effect of various lengths of polymer brushes grafted from graphene oxide particles (GO) surface was investigated. As a polymer matrix the immiscible blend of poly(methyl methacrylate)/styrene-co-acrylonitrile (PMMA/SAN) was used. Thus the poly(methyl methacrylate) (PMMA) brushes grafted from GO (GO-g-PMMA) with various number average molar masses (Mn) of PMMA brushes with respect to chain entanglement limit of freely dispersed PMMA were prepared. The extensional rheological properties were affected by Mn of PMMA brushes, while the rheological properties in shear were unchanged. Transmission electron microscopy revealed the compatibilization effect for short densely grafted brushes with Mn of 10,300 g/mol, as smaller domains were observed. On the contrary, the higher Mn PMMA brushes facilitated coalescence. With increasing length of brushes, the elongational viscosity at low elongation rates (∼< 0.1 s−1) decreased, which facilitated the coalescence. The increase of viscosity at higher elongation rates (∼> 0.1 s−1) was not sufficient enough to cause fiber breakup and thus elongated domains were formed.

Preparation of Al52Sn28Bi20 particles with morphology-controlled core–shell structure by the pulsated orifice ejection method

The core–shell structure is commonly found in immiscible alloy droplets, but their formation route is hindered by the uncontrollable thermal history of droplets prepared through traditional methods. To address this issue, the pulsated orifice ejection method was used to prepare core–shell structure particles with a consistent thermal history. Our study identified a formation route for core–shell structures, wherein the second phase of the outer layer of the particle migrates and coalesces to form the core. It was found that the step time of the pulsated orifice ejection method strongly influenced the final morphology. These findings have significant implications for understanding the formation mechanism of core–shell structures.

Evolution of C-S-H morphology at early age: New insights from direct TEM observation

Numerous types of calcium silicate hydrates (C-S-H) gel morphology have been reported. While the mechanisms of C-S-H solidification and morphology development are still largely unclear. This paper systematically studied the development of C-S-H morphology in a white Portland cement (WPC) paste using transmission electron microscope (TEM). As early as 60 s after mixing, C-S-H gel can be observed on the surface of WPC particle. Four typical C-S-H morphologies, namely featureless, fiber-like, blade-like and foil-like, were found in the suspensions. We demonstrated that C-S-H has multiple steps of morphology change, and significant morphological diversity during the precipitation process. The effect of pH value and calcium concentration on the assemblage procedure and final morphology state of C-S-H was also investigated.