Search

The conventional solid-phase sintering method for the preparation of Ln 2 Ti 2 O 7 ceramics using oxides as reactants generally requires higher temperature, larger pressure, and greater energy consumption. In this paper, we synthesize a Eu 2 Ti 2 O 7 ceramic powder in relatively low-temperature molten salt (KCl–NaCl) using Eu 2 O 3 powder and TiO 2 powder as reactants at 1000 °C. The results of XRD, SEM, and element mapping indicate that the product have high phase purity, good crystal morphology and uniform chemical composition. Moreover, Eu 2 Ti 2 O 7 -based glass-ceramics are obtained by sintering with different contents of borosilicate glass. The SEM images of glass-ceramic show that almost no obvious defects or voids are found on the surface of the samples. The values of water absorption for all glass-ceramic waste forms are less than 0.5 %. With the increase of ceramic embedding rate, the hardness of the glass-ceramics first increases and then decreases, while the density gradually increases. When the embedding rate increased to 30 wt%, the hardness of glass-ceramic reaches a maximum of 19.53 GPa. The glass-ceramic waste form embedded with 30 wt% Eu 2 Ti 2 O 7 exhibits very stable chemical durability with a low leaching rate of 1.42 × 10−8 g m−2 d−1 at 90 °C even after 28 days. [ABSTRACT FROM AUTHOR]

The non-uniformity of a single crystal can sometimes be found in biominerals, where surrounding biomacromolecules are incorporated into the growing crystals. This unique composite structure, combining heterogeneity and long-range ordering, enables the functionalization of single crystals. Polymer gel media are often used to prepare composite single crystals, in which the growing crystals incorporate gel networks and form a bi-continuous interpenetrating structure without any disruption to single crystallinity. Moreover, dyes and many kinds of nanoparticles can be occluded into single crystals under the guidance of gel incorporation. On this basis, the bio-inspired method has been applied in crystal morphology control, crystal dyeing, mechanical reinforcement, and organic bulk heterojunction-based optoelectronics. In this paper, the composite structure, the incorporation mechanisms, and the multiple functions of gel-incorporated single crystals are reviewed. [ABSTRACT FROM AUTHOR]

Context: Ammonium perchlorate (NH4ClO4, abbreviated as AP) has the advantages of high oxygen content, high density, and good compatibility, and has significant application prospects in the field of energetic materials. The crystal morphology has a great influence on the properties and sensibility of energetic materials, and a single experimental means is difficult in exploring the crystals; therefore, the crystal morphology of AP is investigated using molecular dynamics simulation complemented with experiments, to theoretically analyze the differences in AP crystal habit and the interactions between solvent molecules and the main growing crystal surfaces of AP. The results show that AP crystal is mainly composed of five independent crystal surfaces (0 0 1), (0 1 0), (1 0 0), (1 0 1), and (1 0 −1) in vacuum using the BFDH laws, with (0 0 1) surface being the main growth crystal surface. In contrast, in H2O solvent, the (1 0 1) and (1 0 −1) surfaces disappear, and the AP mainly consists of (0 0 1), (0 1 0), and (1 0 0) surfaces with a rectangular shape. The crystal morphology obtained from theoretical prediction is in good agreement with that obtained from experimental culture. This paper can provide a new idea for the cultivation and preparation of AP large crystals, and promote the application of AP crystals in energetic materials. Methods: The crystal morphologies of AP in vacuum and H2O solvent under Dreiding force field were predicted based on attachment energy model by using molecular dynamics method in Materials Studio 2019 software. The entire molecular dynamics simulation was carried out under the NTV system, the temperature control method was selected as Anderson, and the system temperature was set to 298 K. The simulation time was set to 40 ps, the step size was set to 1 fs, and the data were outputted every 5000 steps. [ABSTRACT FROM AUTHOR]

Causticizing precipitated calcium carbonate (CPCC) as a by-product of the green liquor causticizing process can be used as paper filler to save resources and reduce costs. In this study, CPCC was prepared with green liquor and quicklime, which were obtained from an alkali recovery line of a paper mill. The factors influencing crystal morphology of CPCC, such as slaking temperature, slaking time, and causticizing time were investigated. The morphology of CPCC was observed and analyzed for optimizing reaction conditions. The following were compared: properties of CPCC obtained in this study, conventional CPCC (white mud) from a paper mill, and commercial PCC as fillers. The results showed that slaking time and causticizing time were important for morphology control. Spindle-like and rod-like CPCC obtained in this study had better drainability and retention, higher paper bulk, opacity, and physical strength compared to conventional CPCC, and had nearly the same performances as commercial PCC. [ABSTRACT FROM AUTHOR]

This paper proposes a technique for producing underground backfilling materials using enzyme-induced calcium carbonate precipitation (EICP) technology to address the growing ecological security concerns caused by coal mining. To augment the mineralization impact of EICP, diverse levels of organic substances, including yeast extract, peptone, and skimmed milk powder, were incorporated into the cementing solution to offer a greater number of nucleation sites for the precipitation of calcium carbonate. The results indicate that (1) based on visual observations, all the sand columns remained intact after cementation, demonstrating a good cementation effect; (2) unconfined compressive strength (UCS) test findings demonstrated that the introduction of organic components effectively augmented the strength of EICP. Among these materials, skimmed milk powder exhibited the most significant effect, resulting in a 66.01% increase in the UCS of EICP at a concentration of 6 g/L. Peptone also showed a positive impact, albeit to a lesser extent, while yeast powder had a relatively lower effect; (3) The utilization of scanning electron microscopy (SEM) revealed a significant diversification in the crystal morphology of calcium carbonate when combined with organic materials through the EICP process. An X-ray diffraction (XRD) test confirmed the presence of calcite and vaterite. This finding implies that the molecular structure of calcium carbonate is enhanced by the inclusion of organic materials. [ABSTRACT FROM AUTHOR]

This paper provides a detailed technological characterization of the Roman opus sectile glasses (second century AD) coming from the renowned Gorga collection. Nine glass samples corresponding to imitations of the porfido verde antico, cipollino rosso, rosso antico, giallo antico, diaspro nero e giallo, semesanto and agate/alabaster stones were studied. The aim of this study was twofold: (i) archaeometric, i.e., to provide valuable data on the production, raw materials and techniques of these refined Roman glasses that mimic precious stones and (ii) methodological, i.e., to highlight the good performance of combining polished thin sections and local probe measurements for the study of glassy microstructures. Based on the nature of the flux used, the glasses from the samples were classified as either natron-type or mixed-type (natron/plant ash). The latter stem from remelted glasses and contain relict grains of wollastonite that were not found in the pure natron samples. Relict wollastonite crystals appear to be a proficient petrographic marker to spot recycled glasses along with the commonly used chemical fingerprints. Different production and colouring techniques were identified, even for a given type of imitated stone. Metallic Cu, Ca antimonates and Pb-Fe antimonates were the three opacifiers used for the opaque glasses. Based on the crystal morphologies, metallic Cu and Ca antimoniates were possibly synthesized in situ simultaneously with the glass, whilst the Pb-Fe antimonates were prepared ex situ. The working temperatures for these glasses were estimated within the 900–1100 °C range based on the presence and known thermal stability of some identified crystal phases. [ABSTRACT FROM AUTHOR]

An increasing number of researchers are interested in studying CsPbBr3 perovskite solar cells (PSCs) due to their high stability. However, the use of methanol during the spin-coating process is extremely hazardous, both to humans and the environment. CsBr is very soluble in water, but owing to its high specific heat capacity, water causes uneven crystallization and the creation of pores, which negatively impact the performance of CsPbBr3 devices. In this paper, water is introduced as the solvent for CsBr in place of methanol to prepare CsPbBr3 films and ethanol is used as the surface treatment solvent. The morphology and crystal quality of CsPbBr3 films are improved by varying the concentration and spin-coating cycles of the CsBr/H2O solution and adding ethanol post-treatment. The results show that high-quality CsPbBr3 films with reduced grain boundaries and high phase-purity were obtained by spin-coating 100 mg/mL CsBr/H2O solution three times and using ethanol as a post-treatment. The CsPbBr3 solar cells yielded a maximum efficiency of 7.65% and demonstrate long-term stability over 1100 h. [ABSTRACT FROM AUTHOR]

Margarine is a water-in-oil food emulsion and is mostly formulated with selected vegetable oils. This favorable tablespread widely consumes as a butter alternative with both nutritional and economical aspects. The quality of margarine is determined by its textural and rheological properties, which dramatically affect consumer acceptance. Speardability and hardness are considered as the most important textural attributes specifying margarine desirability. The textural and rheological properties of margarine noticeably depend on emulsion characteristics, crystal morphology, processing method, storage condition, fatty acid content and origin. The fat phase of margarine with β′ form crystals develops a smooth and pleasant texture. Rheological measurements could evaluate the emulsion stability, shelf life, meltability and viscoelastic behavior of margarine in different conditions. The physical structure of margarine directly influences spreadability, mouthfeel and meltability and even indirectly impresses on flavor and appearance. This paper focuses on different margarine productions, assesses their viscoelastic and textural characteristics to find out suitable formulation and eventually modifies its physical attributes. [ABSTRACT FROM AUTHOR]

1,1′-Dihydroxy-5,5′-bi-tetrazolium dihydroxylamine salt (TKX-50) is a new type of high-energy low-sense explosive with great application value, but TKX-50 made directly from the reaction has problems such as irregular crystal morphology and relatively large length-diameter, and these factors seriously affect the sensitivity of TKX-50 and limit its large-scale application. The internal defects of TKX-50 crystals have a great influence on their weakness, and studying its related properties is of great theoretical significance and application value. To further investigate the microscopic properties of TKX-50 crystals and to explore the connection between microscopic parameters and macroscopic susceptibility, this paper reports the use of molecular dynamics simulations to construct TKX-50 crystal scaling models with three types of defects—vacancy, dislocation and doping—and conducts molecular dynamics simulations. The influence of TKX-50 crystal defects on the initiation bond length, density, bonding diatomic interaction energy, and cohesive energy density of the crystal was obtained. The simulation results show that the models with a higher bond length of the initiator bond and higher percentage activated the initiator's N-N bond and lowered the bond-linked diatomic energy, cohesive energy density, and density corresponding to higher crystal sensitivities. This led to a preliminary connection between TKX-50 microscopic model parameters and macroscopic susceptibility. The results of the study can provide a reference for the design of subsequent experiments, and the research method can be extended to the research work on other energy-containing materials. [ABSTRACT FROM AUTHOR]

Due to its excellent mechanical properties and high aspect ratio, graphene can significantly improve the water and chloride ion permeability resistance of cementitious materials. However, few studies have investigated the effect of graphene size on the water and chloride ion permeability resistance of cementitious materials. The main issues are as follows: How do different sizes of graphene affect the water and chloride ion permeability resistance of cement-based materials, and by what means do they affect these properties? To address these issues, in this paper, two different sizes of graphene were used to prepare graphene dispersion, which was then mixed with cement to make graphene-reinforced cement-based materials. The permeability and microstructure of samples were investigated. Results show that the addition of graphene effectively improved both the water and chloride ion permeability resistance of cement-based materials significantly. The SEM (scanning electron microscope) images and XRD (X-ray diffraction) analysis show that the introduction of either type of graphene could effectively regulate the crystal size and morphology of hydration products and reduce the crystal size and the number of needle-like and rod-like hydration products. The main types of hydrated products are calcium hydroxide, ettringite, etc. The template effect of large-size graphene was more obvious, and a large number of regular flower-like cluster hydration products were formed, which made the structure of cement paste more compact and thus significantly improved the resistance to the penetration of water and chloride ions into the matrix of the concrete. [ABSTRACT FROM AUTHOR]

MAX phases are layered ternary carbides and nitrides with unique properties, doping transition metals in it is attracting significant attentions for the processing of this relatively new class of materials. In this paper, a magnetic solid solution MAX phase V 2 (Sn 1− x A x)C (A = Mn, Fe, Co) was synthesized by doping Mn/Fe/Co atoms into V 2 SnC by pressure-less sintering. The XRD results show that when x = 0.4, the characteristic peak shifts to the right, and the substitution reaches saturation. SEM and TEM show that doping does not change the original layered morphology and hexagonal crystal form, but only the lattice constants decrease slightly. Magnetic test results indicate that V 2 (Sn 1− x A x)C is a typical low-temperature magnetic material with a Curie temperature around 60 K, and the magnetization increases with the increase of doping amount. Moreover, we explained the reasons of V 2 SnC doping A-site instead of M-site and the changing trend of the magnetic moments by first-principles calculations, which are consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Recently, microbially induced carbonate precipitation (MICP) has shown potent potential in the field of civil engineering. The calcium carbonate crystals produced by bacteria during the MICP process play a central role in sticking the soil. However, the morphological changes of calcium carbonate crystals in this process and the mechanical performance of soil in the corresponding stages have not been clearly explored. In this paper, the alterations in the morphology of calcium carbonate crystals were continuously observed via scanning electron microscopy during the MICP process in one week, and the mechanical changes of the samples were monitored every day, so as to reveal the relationship between the morphology of calcium carbonate crystals and the mechanical performance of the samples. The results show that the calcium carbonate crystals undergo a gradual change from ellipsoid to rhombic at the 72nd hour. The mechanical properties of both were greatly improved, among which the compressive strength was increased by 2.78 times compared with the previous time point, and the flexure strength was increased by 2.57 times; this time point was also the time when calcite appears. In addition, we found direct evidence on the first day that bacteria act as the nucleation site of calcium carbonate formation. The above findings have certain guiding significance for the in-depth understanding of the internal microscopic changes of MICP and the influence of calcium carbonate morphology on sample mechanics. [ABSTRACT FROM AUTHOR]

Human health has been seriously endangered by arsenic pollution in drinking water. In this paper, iron hydroxide nanopetalines were synthesized through a precipitation method using KBH4 and their performance and mechanism of As(V) and As(III) removal were investigated. The prepared material was characterized by SEM–EDX, XRD, BET, zeta potential and FTIR analyses. Batch experiments indicated that the iron hydroxide nanopetalines exhibited more excellent performance for As(V) and As(III) removal than ferrihydrite. The adsorption processes were very fast in the first stage, followed a relatively slower adsorption rate and reached equilibria after 24 h, and the reaction could be fitted best by the pseudo-second order model, followed by the Elovich model. The adsorption isotherm data followed to the Freundlich model, and the maximal adsorption capacities of As(V) and As(III) calculated by the Langmuir model were 217.76 and 91.74 mg/g at pH 4.0, respectively, whereas these values were 187.84 and 147.06 mg/g at pH 8.0, respectively. Thermodynamic studies indicated that the adsorption process was endothermic and spontaneous. The removal efficiencies of As(V) and As(III) were significantly affected by the solution pH and presence of PO43– and citrate. The reusability experiments showed that more than 67% of the removal efficiency of As(V) could be easily recovered after four cycles. The SEM and XRD analyses indicated that the surface morphology and crystal structure before and after arsenic removal were stable. Based on the analyses of FTIR, XRD and XPS, the predominant adsorption mechanism was the formation of inner-sphere surface complexes by the surface hydroxyl exchange reactions of Fe–OH groups with arsenic species. This research provides a new strategy for the development of arsenic immobilization materials and the results confirm that iron hydroxide nanopetalines could be considered as a promising material for removing arsenic from As-contaminated water for their highly efficient performance and stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • (Ni x Co 3− x)S 4 NPs were synthetized through cation exchange started from spinel Co 3 S 4 NP. • Composition-catalytic activity relation of (Ni x Co 3− x)S 4 NPs were established. • Structural modulation induced by ionic diffusion provided additional active sites. • Disordered structure facilitated continuous phase transformation into Co/NiOOH. • (Ni 1.2 Co 1.8)S 4 NPs with tailored chemical and structural properties enhanced OER activity. Transition metal spinels are promising oxygen evolution reaction (OER) catalysts; however, their rational design has been impeded by their inherent elemental and structural complexities. To alleviate these issues, this paper describes the role of cation exchange in developing active OER catalysts whose chemical and structural features are tailored while their morphology and crystal structure are maintained for enabling a systematic comparison. Through cation exchange, pre-synthesized Co 3 S 4 spinel nanoparticles (NPs) transform into (Ni x Co 3− x)S 4 NPs with compositions ranging from Co-rich to Ni-rich phases. Apart from stoichiometry, the atomic disorder and chemical state of the metal cations are amended through excessive interdiffusion and interstitial site preference of the cations, evidently helping boost the catalytic activity. Specifically, (Ni 1.2 Co 1.8)S 4 —which exhibits an optimal Ni/Co ratio, high structural disorder, and distinct surface chemical states—shows excellent OER performance (overpotential at 10 mA/cm2: 298 mV). In-depth analyses including in situ Raman spectroscopy and DFT calculations indicate that (Ni 1.2 Co 1.8)S 4 gradually transforms into OER-active Co/NiOOH—which has a unique electronic structure with strong reaction-intermediate-adsorbing characteristics—during the OER cycles. Overall, the study findings underscore the potency of cation exchange as a tool for controlling structural and chemical features, thereby helping explore complex catalyst materials while enhancing their activity. [ABSTRACT FROM AUTHOR]

Bi 4 O 5 Br 2 /Mn x Zn 1-x Fe 2 O 4 nanocomposites with impressive photocatalytic and recyclability properties were synthesised using a microemulsion method. In addition to the photocatalytic effect, the crystal structure and morphology, photoelectrochemical characteristics, magnetic effect and photocatalytic mechanism of Bi 4 O 5 Br 2 /Mn x Zn 1-x Fe 2 O 4 were also investigated. As the best sample, the removal rate of the Bi 4 O 5 Br 2 /Mn x Zn 1-x Fe 2 O 4 photocatalyst with 7.5 wt% Mn x Zn 1-x Fe 2 O 4 to rhodamine B (RhB) reached up to 99.4% within 60 min. The enhanced photocatalyst activity was mainly attributed to the type-II heterojunction formed between Bi 4 O 5 Br 2 and Mn x Zn 1-x Fe 2 O 4 , which not only optimised the energy band structure, but also led to the building of an interior electromagnetic field within the Bi 4 O 5 Br 2 /Mn x Zn 1-x Fe 2 O 4 heterojunction. Meanwhile, the constantly producing and migrating h+ and ·O 2 − were the main active components. In particular, the results of the saturation magnetization tests and magnetic recovery experiments revealed that the magnetic composite photocatalyst can be recovered effectively. The results of the removal rate of RhB remaining at 85.2% after five uses reflected the advantages of the stability of the Bi 4 O 5 Br 2 /Mn x Zn 1-x Fe 2 O 4 photocatalyst. In brief, this paper presented an original idea to develop a novel composite magnetic photocatalyst and research the enhancement mechanism of photocatalysis. [ABSTRACT FROM AUTHOR]

Filamentous crystals such as whisker crystals are often seen not only in metallic liquids, but also in organic liquids and solutions. They are interesting as reinforce materials. However, it remains challenging to induce filamentous crystals due to an incomplete understanding of the mechanisms behind their formation. In this paper, we investigate filamentous crystal growth in viscous organic liquids. It is found that filamentous crystals grow via an extraordinary dynamical path, where the molecules locally evaporate to bubbles and then redeposite to the tip of growing crystalline filaments. We also succeeded in controlling whether filamentous or faceted crystal growth is selected by inducing or suppressing the bubbles. [ABSTRACT FROM AUTHOR]

Monocrystalline silicon slicing is the first step in making chips, and the surface quality of silicon wafers directly affects the quality of later processing and accounts for a large proportion in the chip manufacturing cost. Ultrasonic vibration assisted wire saw (UAWS) is an effective sawing process for cutting hard and brittle materials such as monocrystalline Si, which can significantly improve the surface quality of silicon wafers. In order to further study the formation mechanism of the surface morphology of single crystal silicon sliced by UAWS, a new model for prediction of wafer surface morphology in UAWS slicing single crystal silicon based on mixed material removal mode is presented and verified by experiments in this paper. Firstly, the surface model of diamond wire saw tool is established by equal probability method. Then, the trajectory equation of arbitrary abrasive particles on the surface of wire saw is derived and analyzed. Thirdly, a new model for prediction of the wafer surface morphology based on mixed material removal mode is presented. Finally, the prediction model is verified by UAWS slicing experiment, and the effects of slicing parameters such as wire saw speed, feed speed, and workpiece rotate speed on the surface quality of silicon wafer were studied. It shows that the predicted wafer surface morphology and the experimental wafer surface morphology are similar in some characteristics, and the average error between the experimental and the theoretical values of the wafer surface roughness is 11.9%, which verifies the validity of the prediction model. [ABSTRACT FROM AUTHOR]

Microfluidics is a new experimental approach that investigates the processes related to fluids flowing through small channels or porous media. Microfluidic chips, the core elements of the microfluidic technique, consist of quasi-2-dimensional pore structures etched and sealed in transparent materials. Fluids are allowed to flow through the chips, and real-time observations can be made about the transport and reactions of fluids at the pore scale. In this study, we test the feasibility of using the microfluidic technique to visualise the microbially induced carbonate precipitation (MICP) process. The experimental results obtained in this study show that the generation, evolution, and morphology of calcium carbonate, the effective product in MICP, can be clearly observed during the entire spatial and temporal range of the tests. Comparative tests with different testing variables, including the concentration of treatment solutions, activity of bacterial suspensions, and particle size, were also carried out. The results show that the influence of these variables on the treatment effects, such as the production rate of the reaction, spatial distribution of calcium carbonate, type and morphology of crystals, amount of ammonia gas produced, and presence/absence of clogging issues, can be visualised in microfluidic chips. The results presented in this paper prove that the microfluidic technique could be a helpful tool for unravelling the mechanisms of the MICP process at the pore scale and understanding the factors influencing the MICP process. [ABSTRACT FROM AUTHOR]

Revealing the internal structure of diamonds is key to understanding the general regularities of crystal growth and dissolution. This paper presents and summarizes data on the internal structure of diamonds of different morphological types, colors and defect-impurity composition. In order to provide a comprehensive explanation of the stages of diamond growth, crystals and plates were observed, and panchromatic cathodoluminescence and photoluminescence techniques were applied. This article considers the mechanism of tangential growth from existing surfaces (regeneration growth) as an intermediate stage between normal and tangential crystal growth. The regeneration growth is very fast due to the absence of the limiting stage-nucleation of a new atomic layer. Cuboid diamonds were refaceted to stepped octahedrons by the regeneration growth mechanism. A schematic model of crystal habit transformation due to regeneration growth explains the internal structure of crystals in connection with their morphology and thermal history. The main variants of regeneration stage and its morphological manifestations were demonstrated. Most diamonds pass through the regeneration stage, and in many cases, it was a stage of growth termination. [ABSTRACT FROM AUTHOR]

Inspired by inorganic oligomers, we herein develop a novel inorganic gel based on calcium oxalate oligomers, and the crystallization morphology has been studied initially in this paper. The prepared oligomer is translucent gel and can exist stably in ethanol, but in aqueous medium it will change from gel to powder. In the crystallization process, because of the volatile speed of solvent and capping agent TEA at different temperature, CaC2O4 oligomer gels (COOGs) exhibited distinct crystallization behavior and morphology. Compared with conventional inorganic crystallization, the crystallization process of the gel at room temperature shows a tendency to gradually extend to the inside of the gel. Moreover, the XRD pattern and SEM images shown that the COOGs achieved distinctly different crystal morphology under different temperature. These provide a preliminary research foundation for the crystallization behavior and control conditions of inorganic gels. [ABSTRACT FROM AUTHOR]

Cerium carbonate crystal morphology is predicted using density functional theory (DFT) simulations in this paper. In the nucleation phase, the ketone group in polyvinylpyrrolidone (PVP) will preferentially bind to Ce3+ to form complexes and provide heterogeneous nucleation sites for the system, prompting the nucleation of cerium carbonate crystals. In the growth stage, due to the adsorption of PVP, the probability of (120) crystal plane appearing in the equilibrium state is the greatest, resulting in the formation of hexagonal flake cerium carbonate crystals with (120) crystal plane as the oblique edge. Experimentally, hexagonal sheet cerium carbonate crystals were successfully prepared using PVP as a template agent. Therefore, DFT can be used to predict the morphology of cerium carbonate crystals, which not only elucidates the growth mechanism of cerium carbonate crystals, but also greatly reduces the experimental cost. [ABSTRACT FROM AUTHOR]

During the preparation process of LiNi 0 · 6 Co 0 · 2 Mn 0 · 2 O 2 (NCM622) material via solid-phase method, the obtained NCM622 particle size is often inconsistent due to the inhomogeneous phase mixing, which makes the NCM622 material have low specific capacity and poor rate performance, and thus restrict the application of solid-phase method. In order to solve this problem and make full use of the advantages of solid-phase method, liquid-phase assisted mixing is used to replace the traditional mechanical mixing. At the same time, polyvinylpyrrolidone (PVP) is introduced to control the crystal morphology and particle size, thus a NCM622 material with excellent electrochemical energy storage performance has been prepared by the PVP modified liquid-phase assisted solid-state method in this paper. X-ray diffraction, scanning electron microscopy and Raman spectroscopy are used to characterize the morphology structure of the obtained materials. Their electrochemical energy storage performance is tested by program-controlled battery tester and electrochemical workstation after being assembled into button cells. The research results show that with the introduction of PVP, the particle size of the obtained material becomes smaller, the particle size distribution is more uniform, and the degree of cation mixing is further reduced. When the PVP adding amount is up to 1.6 wt %, the obtained material shows the best electrochemical performance: its first discharge specific capacity and coulomb efficiency are 183.19 mAh.g−1 and 88 % (0.1C), respectively. The capacity retention rate is 96.5 % after 100 cycles at 1C (half-cell system and laboratory conditions), which is comparable or better than those by other preparation methods, showing a good application prospect. [ABSTRACT FROM AUTHOR]

This paper focuses on the multi-dimensional performance analysis including the oxidation performance, crystal morphology, thermal properties, mechanical properties and dielectric behavior of the thermally aged extra high voltage XLPE submarine cable insulation. Results show that the antioxidation and thermal oxidative aging of XLPE insulation are coexisting and competing during the thermal degradation process. In the early stage of thermal degradation, the antioxidation of XLPE insulation is dominant resulting in the decline of the spacing between spherulites. In the later stage of thermal degradation, thermally oxidative aging of XLPE insulation is dominant, which leads to the damage of the crystalline morphology and the rapid generation of aging products. It is indicated that the mechanical strength of the XLPE insulation is mainly determined by its internal crystalline morphology, while the dielectric properties of the XLPE insulation are governed by the crystalline morphology, aging products and micro interface. With the thermal aging time extended, the breakdown strength of XLPE insulation first increases and then decreases, which is determined by its amorphous region and aging products. [ABSTRACT FROM AUTHOR]

Alkaline-earth metal-based MOF has many merits such as light weight, environmental friendliness and low cost, but it has rarely been used in energy storage and capacitive deionization (CDI). This paper presents a facile method for the fast synthesis of small-size magnesium formate MOF (Mg-MOF) under mild conditions by linker-free incubation in the presence of Mg(CH3COO)2⋅ 4H2O and dimethylformamide. The formic acid was in situ formed as ligand to facilitate the formation of Mg-MOF. The effect of incubation time on the morphology of MOF crystals was investigated. The small and well-defined Mg-MOF particles with the size of ~ 18 nm were formed in 1 h incubation, characterized by scanning electron microscopy and X-ray diffraction. Following carbonization, the Mg-MOF-derived mesoporous carbon was obtained. N2-sorption isotherm confirmed the mesoporous structure. Cyclic voltammetry test indicated the good electric double-layer feature of the Mg-MOF-derived carbon electrode, and the impedance results showed the excellent conductivity. As a capacitor electrode material, it delivered the specific capacitances of 102 F/g by GCD (0.2 A/g). The Mg-MOF-derived carbon electrode was applied successfully for capacitive deionization (CDI) with a desalination capacity of 8.0 mg/g in a CDI device. A supper fast desalination rate of 1.1 mg/g/min was achieved due to the abundant mesoporous structure. The work provides a cost effective and environmentally friendly way for the synthesis of MOF-based carbon materials free of transition metal, and the prospects for CDI application have been demonstrated. [ABSTRACT FROM AUTHOR]

The paper is devoted to the study of ferroelastoelectric domain structure and peculiarities of nano- and microcrystals growth on the surface of [(CH3)2CHNH3]4Cd3Cl10 (IPACC) crystals. The domains in the ferroelastoelectric phase lying below 294 K were visualized using an atomic force microscope. It was shown that the surface morphology of IPACC crystals kept for a long time (from one up to twelve months) in open air undergoes considerable changes in comparison with the freshly cleaved samples. Our samples are characterized by the growth of nanocrystals at the first stage and larger microcrystals at the next stages of the sample aging. Other types of elements observed on the surface were nanoor microrods. The model describing the peculiarities of the surface morphology and domain structure modification arising in the process of aging was proposed. [ABSTRACT FROM AUTHOR]

Reasonable slag fluidity is essential for stable HIsmelt process operation. During the slag-tapping process, crystallization will cause the slag viscosity to rise sharply, which is not conducive to stable slag-tapping operation, especially for smelting high-titanium slag. In this paper, the viscosity of the CaO-MgO-Al 2 O 3 -SiO 2 -TiO 2 -FeO slag with varying 10–50% TiO 2 content was studied in the laboratory. The crystalline phases of water quenched slag samples at different temperatures were determined by XRD, and it was verified with the results of Factsage thermodynamic calculations. In addition, the effects of crystalline phase, crystalline morphology and crystal size on the critical viscosity of slag were discussed through SEM-EDS analysis. The results show that the proper TiO 2 content in the slag is below 40%, the temperature of critical viscosity (T cv) of the slag is between 1336 °C and 1360 °C, and the T cv of the slag with a TiO 2 content of 50% increases to 1500 °C. The sudden increase in viscosity is related to the crystallization behavior of the slag. With the increase of TiO 2 content, the main precipitated titanium-rich phase in the slag changed from dendritic perovskite to plate-shaped pseudobrookite. Among them, when the TiO 2 content is 10%, the sharp increase in viscosity of the slag is mainly determined by the precipitation amount of melilite. The amount of crystals in the slag between 20% and 43% causes the viscosity of the slag to rise rapidly, which is mainly due to the fact that the granular crystals have a greater influence on the viscosity than the plate crystals. Compared with the experimental results, it is found that Factsage software cannot accurately calculate the phase equilibrium of slag with a TiO 2 content of 40–50%. [ABSTRACT FROM AUTHOR]

In this paper, we discuss information on crystal structure and morphology available from nuclear magnetic resonance (NMR) spectroscopy of 207Pb for the mineral family [Pb(4f)]2[Pb(6h)]3(AO4)3Cl with A = V (vanadinite), P (pyromorphite), and As (mimetite). The isotropic chemical shift of the 207Pb atoms at Wyckoff positions 4f and 6h was (re-)determined from either static single-crystal or magic angle spinning NMR experiments. This isotropic shift can be linearly correlated to the unit-cell volume within the mineral family, and in the wider context of lead-bearing minerals, to the shortest Pb-O distance for position 4f, in which 207Pb is solely coordinated by oxygen. By evaluating the number of resonances and their respective line widths in the 207Pb-NMR spectra of these three naturally grown minerals, it could be established that vanadinite forms single-domain macroscopic crystals with very small mosaicity, whereas pyromorphite crystals show NMR characteristics, which can be interpreted as being caused by significant mosaicity. In some instances, this mosaic spread could be quantitatively approximated by a Gaussian distribution with a standard deviation angle of σ = 5°. In contrast, our mimetite specimen was composed of multiple sub-crystals with a very high variability of orientations, going beyond mere mosaicity effects. By extending the NMR methodology presented here to other minerals, it may be possible to gain new insights about structure-property relationships and the morphology of natural grown minerals. [ABSTRACT FROM AUTHOR]

For further energy enhancement of water-reactive metal fuels, it is crucial to find aluminum composites that can react synchronously and quickly with multiple types of water (ice, steam, and water). In this paper, two graphite-based aluminum composites, aluminum/bismuth/graphite (Al/Bi/GI) and aluminum/bismuth/graphene nanosheets (Al/Bi/GE), were prepared. The morphology and crystal structure of the composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The reactivity of Al/Bi/GI and Al/Bi/GE with water from 20 °C to 80 °C and ice at 0 °C and −15 °C was characterized using hydrogen generation properties. Their ignition and combustion properties in high-temperature water steam from 300 °C to 900 °C were also investigated. The results show that Al/Bi/GI and Al/Bi/GE composites prepared by ball milling have blocky and multilayered lamellar structures, respectively. That ball milling does not result in the formation of new alloys. The thickness of graphite material affects the reactivity of activated aluminum composites. The hydrogen generation rates of Al/Bi/GE in water and ice are much higher than that of Al/Bi/GI. The maximum hydrogen generation rates of Al/Bi/GE were 28.8 and 46.6 times higher than those of Al/Bi/GI in water at 20 °C and ice at −15 °C, respectively. In high-temperature water steam, the ignition temperature and ignition delay time of Al/Bi/GE are lower than those of Al/Bi/GI. Al/Bi/GE achieves a rapid reaction that can be synchronized with three forms of water and is expected to be applied to water-reactive metal fuel propellants. • Al/Bi/GI and Al/Bi/GE composites with different structures were prepared. • The multilayered lamellar structure of Al/Bi/GE has superior synergistic reactivity with different forms of water. • The MHGR of Al/Bi/GE on ice at −15 °C is 12.6 mL‧g-1‧s-1, 46.6 times higher than that of Al/Bi/GI. • Al/Bi/GE exhibits better combustion performance in high-temperature steam. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis, structure, BFDH crystal morphology, Raman and Infrared spectroscopic studies of three novel metal orthophosphate salts MII(Ga 0.5 Sb 0.5)(PO 4) 2 (MII= Sr, Pb, Ba), abbreviated [Sr], [Pb], [Ba]. The structures of these phases are refined from X-ray powder diffraction data by the Rietveld method. The yavapaiite [Ba] phase is monoclinic of C2/m space group [Z=2; a= 8.106(4) Å; b= 5.178(3) Å c= 7.806(1) Å, β=94.79(4)°, V= 327(1) Å3]. Its structure consists of layers, running along the (a, b) plane, and built up of corner-connected Ga(Sb)O 6 octahedra and PO 4 3− tetrahedra. The two isotypic phases [Sr]/[Pb] of distorted yavapaiite structure crystallize in the monoclinic C2/c space group (Z=4) with parameters: a=16.455(4)/16.622(7) Å; b=5.158(1)/5.163(2) Å c= 8.005(1)/8.067(3) Å; β=115.49(1)/114.85(2)°, V= 613(1)/628(5) Å3. Their structures consist of MO 10 (M= Sr, Pb), PO 4 3− tetrahedra and Sb(Ga)O 6 octahedra. In [Pb] phase, the Pb is surrounded by eight oxygen atoms (Pb-O: 2.65-2.77 Å) and two oxygen atoms forming abnormal bond distances Pb-O(4) [3.447(3)Å]. The BFDH crystal morphology predicts hight (h k l) facets for each compound, the center-to-plane distances d hkl are slightly strong in the distorted Yavapaiite [Pb/Sr] rather than in [Ba]. The IR and Raman study is performed based on theoretical group analysis considering C s site symmetry of PO 4 3− groups in [Ba], and C i symmetry in [Pb]/[Sr] phases. The assignment and discussion of the observed bands were done by comparison with other yavapaiite materials. The UV–visible investigation reveals direct optical gap energies of values 4.16 eV for [Ba] and 4.24 eV for [Sr], indicating a semi-conducting nature of the prepared materials. Crystal structures, UV absorbance, and and Tauc Plots (F(R)hν)1/2 of versus hν of AII(Sb 0.5 Fe 0.5)(PO 4) 2 (AII = Ba, Pb, Sr) compounds. [Display omitted] • Novel A(Sb 0.5 Ga 0.5)(PO 4) 2 (A= Ba, Pb, Sr) crystal structures are determined and discussed. • The BFDH morphology of [Ba] and [Sr] are simulated from parametres and Laue symmetry of these crystals. • Theoretical analyses are made in assignment of IR and Raman bands for the three phases. • UV–visible absorptions indicate a semi-conducting nature of the synthetised materials. [ABSTRACT FROM AUTHOR]

SmCo5 is one of the most promising candidates for achieving a hard magnet with a high coercivity. Usually, composition, morphology, and size determine the coercivity of a magnet, however, it is challenging to synthesize phase pure SmCo5 with optimal size and high coercivity. In this paper, we report on the successful synthesis of phase pure SmCo5 with spherical/prolate spheroids shape. Size control is obtained by utilizing colloidal SiO2 as a template preventing aggregation and growth of the precursor. The amount of SiO2 nanoparticles (NPs) in the precursor tunes the average particle size (APS) of the synthesized SmCo5 with particle dimension from 740 to 504 nm. As-prepared pure SmCo5 fine powder obtained from using 2 ml SiO2 suspension possesses an APS of 625 nm and exhibits an excellent coercivity of 2986 kA m−1 (37.5 kOe) without alignment of the particles prior to magnetisation measurements. Comparing with a reference sample prepared without adding any SiO2 NPs, an enhancement of 35% of the coercivity was achieved. The improvement is due to phase purity, stable single-domain (SSD) size, and shape anisotropy originating from the prolate spheroid particles. [ABSTRACT FROM AUTHOR]

The study on the surface morphology and crystal orientation of the Zn-0.5Sn coating could offer some guidance to improve the surface performance of the hot-dip galvanizing coating. In this paper, a scanning electron microscope (SEM) and an energy dispersive spectrometer (EDS) were used to analyze the typical morphology and the element distribution of spangles. The surface texture of the coating was analyzed by X-ray diffraction (XRD). Electron backscatter diffraction (EBSD) was used to analyze the crystal orientation of spangles. The results show that Sn segregates among the spangle dendrites while a metastable divorced eutectic structure can be maintained in the tin-rich phase, where the composition tends to be very similar. The crystal orientation of spangles affects their morphology, leading to the formation of feathery, ridged, and orthogonal dendrite arm spangles. When the angle among the <0001> orientation of the spangle crystal and the normal of the steel base surface changes from 0° to 90°, feathery spangles change to orthogonal dendrite arms spangles. The misorientation within a spangle is small while that among spangles is quite large. The orientation changes in the direction of the dendrite arm are relatively smooth and low, while the orientation changes which are perpendicular to the dendrite arm have a saltatory and irregular fluctuation. [ABSTRACT FROM AUTHOR]

Polypropylene (PP)/elastomer blend is a promising candidate for high voltage direct current (HVDC) cable insulation. Space charge accumulation in HVDC cable is an important factor for safe and stable operation of HVDC transmission system. In this paper, propylene based elastomer (PBE) and ethylene-octene copolymer elastomer (EOC) were added into PP to prepare the blend sample. Space charge accumulation behavior was estimated by the pulsed electro-acoustic (PEA) method, and the influence of compatibility between the PP and the elastomer on the charge accumulation behavior was investigated. Polarized optical microscope (POM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and dynamic mechanical analysis (DMA) measurements were performed to assist the understanding of the compatibility dependent space charge accumulation behavior. The obtained results showed that the amount of space charge in the PP/PBE blend was lower than that in the PP/EOC blend. As compared with the PP/EOC blend, higher crystallinity with integrated crystal morphology and β-crystal form were observed in the PP/PBE blend for better compatibility between PP and PBE. It is suggested that deeper trap centers are formed in the PP/PBE blend than in the PP/EOC blend due to the compatibility, by which the charge injection is restricted. [ABSTRACT FROM AUTHOR]

The deposition of CaCO 3 scale in circulating cooling water on metal surface is a major concern in industry. This paper focuses on the feasibility of electrochemical methods to study the scale inhibition performance of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), Polyacrylic Acid (PAA), including linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS). In addition, the coverage, morphology and structure of deposited CaCO 3 crystal on titanium alloy surface in the absence and presence of inhibitors were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A new method for calculating the efficiency of scale inhibitors was proposed so that it can be calculated by using the change in residual current density (i r). In order to prove the feasibility and accuracy of such method, the efficiencies of inhibitors were evaluated using i r and charge transfer resistance (R ct), respectively. In addition, molecular dynamics (MD) simulations were performed to evaluate the interaction between the scale inhibitor molecule and the CaCO 3 crystal. The experimental results show that both the residual current density obtained by chronoamperometry and the charge transfer resistance obtained by electrochemical impedance spectroscopy can be used to evaluate the efficiency of scale inhibitors, and there is high consistency from the calculation results. It is also confirmed by X-ray diffraction and scanning electron microscopy studies that the presence of inhibitor reduces the surface coverage of CaCO 3 at metal electrode and that the crystal structure of CaCO 3 is transformed from the original aragonite into the most unstable vaterite. The best inhibition efficiency of PBTCA for CaCO 3 deposit is confirmed by the results of MD simulations. [ABSTRACT FROM AUTHOR]

The role of epitaxial strain and chemical termination in selected interfaces of perovskite oxide heterostructures is under intensive investigation because of emerging novel electronic properties. SrTiO 3 (STO) is one of the most used substrates for these compounds, and along its < 001 > direction allows for two nonpolar chemical terminations: TiO2 and SrO. In this paper, we investigate the surface morphology and crystal structure of SrO epitaxial ultrathin films: from 1 to about 25 layers grown onto TiO 2 -terminated STO substrates. X-ray diffraction and transmission electron microscopy analysis reveal that SrO grows along its [ 111 ] direction with a 4% out-of-plane elongation. This large strain may underlay the mechanism of the formation of self-organized pattern of stripes that we observed in the initial growth. We found that the distance between the TiO 2 plane and the first deposited SrO layer is 0.27 (3) nm, a value which is about 40% bigger than in the STO bulk. We demonstrate that a single SrO-deposited layer has a different morphology compared to an ideal atomically flat chemical termination. [ABSTRACT FROM AUTHOR]

This paper uses a network of ideal flow reactors and a detailed population balance model to study the evolution of the size and shape distributions of pigmentary titanium dioxide, formed under industrial synthesis conditions. The industrial reactor has multiple reactant injections, a tubular working zone in which the exothermic reaction is completed, and a cooling zone. A network of continuously stirred tank reactors is used to model variation in composition around the feeds and plug flow reactors with prescribed temperature gradients are used to describe the working and cooling zones. The quality of the industrial product depends on its morphology, and this is influenced by factors including temperature and throughput. In this paper, a multivariate particle model is accommodated using a stochastic method and the particle morphology is characterised in terms of the distributions of primary and aggregate particle diameters, number of primary particles per particle and neck radii of connected primary particles. Increasing temperature or residence time is shown to produce larger particles. Qualitative similarities are highlighted between such findings and previous studies. The throughput studies are also in qualitative agreement with empirical industrial experience. There is scope for extending and improving the current model; however, it is suggested that insights of this type could be used to inform the design and operation of the industrial process. [ABSTRACT FROM AUTHOR]

In all the waters where mollusks can grow, a variety of metal ions abounds. Attention has focused, however, on the effects of K+, Na+ and Mg2+ on the biomineralization of nacre, and those of other metal ions have been relatively neglected. This paper investigated the effects of representative copper (II) on the biomineralization of CaCO 3 using egg white as the organic matrix. The effects of copper ion concentration, aging time and the combined actions of a high concentration of both egg white and Cu2+ on the morphology and crystal type of CaCO 3 were studied, and the action mechanism was analyzed. The results show that copper (II) can induce the formation of vaterite, promote the spheroidization of mineralized particles, distort and deform the lamellar structure, and affect the surface roughness. Mechanism analysis shows that the bending and twisting of the protein molecule chain caused by the biuret reaction of Cu2+ with egg-white protein is the primary reason for the effects of copper (II) on the morphology and crystal type of CaCO 3. On this basis, a micron pearl-like CaCO 3 with a spherical structure consisting of uniform lamellae about 350 nm thick was obtained by exploiting the combined actions of high concentrations of egg white and Cu2+. [ABSTRACT FROM AUTHOR]

Graphical abstract The cotton fabrics with superhydrophobic and superolephobic underwater were fabricated in this paper via controlling ZnO crystal morphology and choosing various modification agents, and the results showed that they possessed efficient separations as need for oil/ water mixtures with both an efficiency and a high flux. Abstract Based on controlling ZnO nanoarrays morphology and employing fluorine-free modification agent, superhydrophobicity in air and superoleophobicity under water were successfully achieved on the prepared cotton fabric surfaces via a two-step hydrothermal reaction. To increase adhesion between ZnO crystal layer and substrate surface, two kinds of silane coupling agents (hydrophobic TTOP-12 and hydrophilic KH550) were added selectively in the pretreatment process. The as-prepared fabric exhibited great tolerance and durableness towards external harsh environments, such as mechanical abrasion, UV radiation, immersion of acid or alkali, and high temperature. In comparison, superhydrophobic fabrics showed superior separation effect for heavy oil and water mixture, while underwater superoleophobic fabric can also show efficient separation of water and light oil with high separation efficiency and flux. In a word, heavy/light oil and water mixtures can be separated efficiently as need by choosing cotton fabrics with various wettabilities. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this paper is to extract a clearer relationship between atomic properties of the oxidizer, and ignition temperature and combustion kinetics. Pure Bi 2 O 3 and a series of Y3+ and W6+ doped Bi 2 O 3 nanoparticles with the same crystal structure and morphology were synthesized via aerosol spray pyrolysis and used as oxidizers in boron-based thermites. This enabled us to vary bond energy and oxygen vacancy concentration systematically. The ignition temperatures and the reactivities of different B/Bi 2 O 3 thermites were measured by rapid heating (> 105 K/s) temperature-jump/time-of-flight mass spectroscopy and a confined pressure cell, respectively. With pure Bi 2 O 3 , the boron could be ignited at a temperature as low as 520 °C. In-situ high heating rate TEM was used to observe the reaction before/after heating. We find very clear relationships that higher oxygen vacancy concentration and smaller metal–oxygen bond energy lead to lower ignition temperature and higher combustion reactivity. [ABSTRACT FROM AUTHOR]

In this paper, the effect of TiO 2 ceramic nanoparticles on the thermal stability, morphology, molecular mass, structure and electrical properties of the polylactic acid-Titanium dioxide (PLA-TiO 2 ) composites, aimed for relative humidity (RH) sensing have been reported. PLA-TiO 2 nanocomposites films were developed through a spin coating process. The developed films were characterized by X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and electrochemical impedance spectroscopy analysis (EIS). To investigate the RH-dependent characteristics, the devices were prepared on pre-patterned ITO substrates. The capacitive and resistive response of the nanocomposite films were studied under RH levels ranging from 20–90%. The PLA-TiO 2 nano-sensing films, having modified surface by acetone etching, exhibited superior morphological and electrical performance when compared to PLA-TiO 2 pristine samples. [ABSTRACT FROM AUTHOR]

The fabrication of 3-D parts from CAD models by additive manufacturing (AM) is a disruptive technology that is transforming the metal manufacturing industry. The correlation between solidification microstructure and mechanical properties has been well understood in the casting and welding processes over the years. This paper focuses on extending these principles to additive manufacturing to understand the transient phenomena of repeated melting and solidification during electron beam powder melting process to achieve site-specific microstructure control within a fabricated component. In this paper, we have developed a novel melt scan strategy for electron beam melting of nickel-base superalloy (Inconel 718) and also analyzed 3-D heat transfer conditions using a parallel numerical solidification code (Truchas) developed at Los Alamos National Laboratory. The spatial and temporal variations of temperature gradient (G) and growth velocity (R) at the liquid-solid interface of the melt pool were calculated as a function of electron beam parameters. By manipulating the relative number of voxels that lie in the columnar or equiaxed region, the crystallographic texture of the components can be controlled to an extent. The analysis of the parameters provided optimum processing conditions that will result in columnar to equiaxed transition (CET) during the solidification. The results from the numerical simulations were validated by experimental processing and characterization thereby proving the potential of additive manufacturing process to achieve site-specific crystallographic texture control within a fabricated component. [ABSTRACT FROM AUTHOR]

• The morphology of the ice tip on different surfaces were recorded with microscope. • Contact angles of ice on substrate are obtuse and decrease with temperature as Sigmoid function • Surface energy can affect substrate icing by altering the ice tip and heat transfer • The ice contact angle is found to be pretty closed to the ice nucleus contact angle As one of the long-standing crucial theoretical assumptions of the heterogeneous nucleation and substrate icing theory, the tiny shape of an ice tip on the substrate commands further detailed experimental observation. In this paper, the morphology and growth processes of ice on different near-thermal insulation surfaces at a low supercooling degree were observed by microscope. Experimental results show that the contact angles of the dendritic ice tip on the substrates are all obtuse under a lower supercooling degree, and decrease with temperature as a Sigmoid function. Moreover, the analysis of ice growth on different substrates reveals that the surface property can affect substrate icing by altering the ice tip; that is, as the ice contact angle increases, the radius will increase and the influence of the thermal conduction of substrate on the ice tip will decrease, ultimately leading to a slower growth rate. Significantly, heterogeneous nucleation experiments illustrate that the obtained ice contact angle is close to the ice nucleus contact angle. Consequently, compared with previous theories, the temperature-dependent ice contact angle could be used to accurately predict the nucleation rate and ice growth. [ABSTRACT FROM AUTHOR]

An attempt was made to develop a general description of impact sensitivity. For this purpose a set of 24 well-known, as well as recently synthesized, C-H-N-O-Cl explosives covering the wide range of impact sensitivity (h50 = 9-320 cm) was studied using first-principles calculations at different external pressures. To quantify impact sensitivity, a theoretical approach was developed based on the solid-state derived criteria, which include triggering pressure, average number of electrons per atom, crystal morphology, energy content and melting temperature. These criteria follow from the theoretical consideration of the crystal compression caused by an impact event. Apart of the compression, the influence of crystal habit shapes and energy content are also discussed. The main idea is in the electron flow probability from valence to conduction bands in a solid. To support the developed theoretical background, the corresponding numerical illustration is presented in the paper. The obtained empirical correlation exhibits a significant regression coefficient (R2= 0.83). Furthermore, the found criteria have complementary character. When using them individually, the correlation becomes poor or even vanishes. Thus, a sensitive to impact explosive is expected to be more easily convertible to the metal upon compression, to possess a spherical crystal habit and to have a greater number of electrons per atom as well as a high energy content and a low melting temperature. Consequently, an insensitive explosive has the inverse characterization. [ABSTRACT FROM AUTHOR]

Developing metal oxide nanocomposite with superior gas-sensing properties is an important subject in the field of gas sensor. In this paper, we reported a facile synthesis route for ZnFe 2 O 4 /α-Fe 2 O 3 porous microrods (PMRs) by using dual oxalates as sacrificial template. FeC 2 O 4 ·2H 2 O solid microrods (SMRs) were first synthesized by a chemical precipitation reaction between FeSO 4 ·7H 2 O and H 2 C 2 O 4 ·2H 2 O, which were then immersed in Zn 2+ aqueous solution to obtain the hybrid ZnC 2 O 4 ·2H 2 O/FeC 2 O 4 ·2H 2 O SMRs through the substitution reaction between Zn 2+ and Fe 2+ . After a proper annealing process, ZnFe 2 O 4 /α-Fe 2 O 3 PMRs were successfully prepared through the decomposition of ZnC 2 O 4 ·2H 2 O/FeC 2 O 4 ·2H 2 O SMRs. The prepared ZnFe 2 O 4 /α-Fe 2 O 3 PMRs are about 2–5 μm in length and 0.3–0.5 μm in diameter, and constructed by numerous loosely stacked nanoparticles with the size about 15 nm. The dominant pore size in ZnFe 2 O 4 /α-Fe 2 O 3 PMRs is around 10 nm. The results of gas-sensing tests indicates that through decorating the α-Fe 2 O 3 PMRs with ZnFe 2 O 4 , the response of the sensor towards TEA is remarkably improved. For example, the response of the composite sensor to 100 ppm TEA is as high as 42.4, which is about 20 times higher than that of the bare α-Fe 2 O 3 PMRs sensor (2.5). The enhanced TEA sensing mechanism of ZnFe 2 O 4 /α-Fe 2 O 3 PMRs was discussed in detail. [ABSTRACT FROM AUTHOR]

The paper presents results of studies of composite nickel/graphene coatings produced by electrodeposition method on a steel substrate. The method of producing composite coatings with nanocrystalline nickel matrix and dispersion phase in the form of graphene is presented. For comparative purposes, the study also includes nano-crystalline Ni coatings produced by electrochemical reduction without built-in graphene fl akes. Graphene was characterized by Raman spectroscopy, transmission and scanning electron microscopes. Results of studies on the structure and morphology of Ni and Ni/graphene layers produced in a bath containing different amounts of graphene are presented. Material of the coatings was characterized by SEM, light microscopy, X-ray diffraction. The microhardness of the coatings was examined by Knoop measurements. The adhesion of the coatings with the substrate was tested using a scratchtester. The influence of graphene on the structure and properties of composite coatings deposited from a bath with different graphene contents was determined. [ABSTRACT FROM AUTHOR]

In this paper, ultra-small Au nanoparticles (1–2 nm) were successfully decorated on the surface of three-dimensional porous wool like ZnO microspheres through a facile, surfactant-free and green precipitation manner. The ZnO microspheres were synthesized via a hydrothermal method. The crystal structure and morphology of the samples as-synthesized were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed that quantities of Au nanoparticles of which the diameter ranged about 1–2 nm were distributed evenly on the surface of ZnO microspheres. Gas sensing measurements revealed that the ZnO microspheres decorated with ultra-small Au nanoparticles (Au-ZnO microspheres) showed ultrasensitive and selective detection to acetylene. The Au-ZnO microspheres exhibited ultra-higher response to acetylene (311.3–100 ppm acetylene) at a lower optimal working temperature (183.5 °C) compared with pure ZnO microspheres. Meanwhile, The Au-ZnO microspheres displayed a fast response/recovery speed (about 1 s and 20 s, respectively). Besides, the Au-ZnO microspheres also showed good stability and repeatability over a two-month testing period. Furthermore, the formation of schottky junction, the catalytic effect of Au nanoparticles and the physical advantages of the nanomaterial in size and structure could be three dominant factors to the superior acetylene sensing performance. [ABSTRACT FROM AUTHOR]

In the present paper new detailed kinetic model for the methanol synthesis from H 2 , CO 2 and/or CO using a Cu/ZnO/Al 2 O 3 catalyst is proposed. In contrast to most established models different active surface species for CO and CO 2 hydrogenation are taken into account. It is shown that changes in the relative amounts of these different surface species, which are related to changes in catalyst morphology, play an important role for the dynamic transient behavior. The model is therefore suitable for evaluating new applications in chemical energy storage, where strongly varying ratios of CO and CO 2 are of relevance. The model parameters were fitted to steady state and dynamic experimental data for varying CO/CO 2 feed ratios using global optimization. Identifiability is studied using the Profile-Likelihood method giving rise to a reduced kinetic model. [ABSTRACT FROM AUTHOR]

In this paper, NiO nanoparticles were prepared by hydrothermal synthesis of Ni(OH) 2 precursors using different alkalis (NH 3 and NaOH) followed by a calcination at different temperatures (400 °C and 600 °C) and characterized by XRD and SEM. Their electrochemical and optical properties were probed by cyclic voltammetry and reflectance spectroscopy and related to the structural and morphological properties. It was found that the smallest peak-to-peak separations and band gaps attain to the NiO nanoparticles prepared at 400 °C, which are smaller and more porous. The preparations at 600 °C correspond to larger nanoparticles, with a larger size distribution and in one case (preparation with NaOH) a compact structure. The associated band gaps are larger and the electrochemical performances worse. [ABSTRACT FROM AUTHOR]

Application of the foam scaling laws to the mechanical properties of nanoporous gold (np-Au) implicitly assumes geometrical similarity of structures of different relative density and synthesis methods. While the very few studies addressing the issue of geometric similarity during thermal coarsening show contradicting results, there are no studies covering np-Au from different synthesis routes. This paper performs quantitative morphological and topological comparison of np-Au of ca. 30% relative density synthesized by free and electrochemical corrosion methods, and thermally coarsened samples. Nanoindentation tests were performed to obtain elastic modulus and hardness. Uniaxial compression simulations of three-dimensional structures from FIB-nanotomography have been conducted using finite element analysis, and the results are compared with experiments. The three-dimensional np-Au structure has been quantified in terms of the ligament diameter and length distributions, ligament tortuosity, surface curvature distributions, structural anisotropy, nodal connectivity, and genus. Our results suggest that neither the synthesis route nor the thermal coarsening, to change length scale by up to a factor of 3, significantly altered the morphology and topology. The modulus and strength from both experiment and simulations exhibit a linear dependency on the scaled genus density, modifying the geometry-dependent prefactors in the Gibson and Ashby scaling relations. [ABSTRACT FROM AUTHOR]

Birnessite-type manganese oxide is a highly efficient oxidant that has been investigated widely for As(III) oxidation. Nevertheless As(III) oxidation rate is inevitably reduced due to favorable adsorption of coexisting ions and As(V) which passivate its surface. In this paper we explore a novel strategy to significantly improve As(III) oxidation performance by controlling birnessite morphology. The batch experiment results show that the nanoflower-like birnessite (Bir-NF) exhibits an incredible improvement in As(III) oxidation activity compared to nanowire-like (Bir-NW) and nanosheet-like (Bir-NS) birnessites. The morphology of birnessite varies from nanosheet to nanoflower not only promotes As(III) oxidation rate from 1.4 to 24.7 μmol g −1 min −1 , but also reduces the adverse effect of adsorption of As(V) and coexisting ions on As(III) removal. The origin of morphology-dependent enhancement of As(III) removal was experimentally and theoretically studied by As(V) adsorption on birnessites, phosphate adsorption kinetics, detection of dissolved Mn 2+ concentration, average Mn oxidation state, the point of zero charge, and density functional theory (DFT) calculations. The results reveal that significant enhancement of As(III) oxidation activity in Bir-NF as compared to Bir-NW and Bir-NS is attributed to its highly efficient contact between As(III) species and manganese oxide, as well as its fast charge transfer from As atom to Mn atom due to its highest oxygen vacancy defect concentration, thus significantly promoting As(III) oxidation activity. [ABSTRACT FROM AUTHOR]

In this paper, the influence of rubber particle size on the phase interface in dynamically vulcanized poly(vinylidene fluoride)/silicone rubber (PVDF/SR) blends without any modifier is discussed through the studies of specific surface of crosslinked SR particles, crystallization behavior and crystal morphology of the PVDF phase, interfacial crystallization, melt rheological behavior and mechanical properties of blends. A series of decreased average particle size was successfully obtained by control of rotor rate. It was found that properly high rotor rate helped to achieve a reduced particle size and a narrowing size distribution. The reduced SR particle size enlarged the PVDF/SR interface which has a positive effect on the interfacial crystallization and the melt rheological behavior. At high SR content, the negative effect of the poor interface interactions played the dominate role on determining the mechanical properties. However, the blend exhibited a unique stiffness-toughness balance at the PVDF/SR = 90/10. We hope that the present study could help to lay a scientific foundation for further design of a useful PVDF/SR blend with promoted properties to partly replace the high-cost synthetic fluorosilicone materials. [ABSTRACT FROM AUTHOR]