Low Degree Of Crystallization Research Articles

Enhanced low-temperature selective catalytic reduction (SCR) activity and H2O and SO2 resistance of flower-like SmMnOx and SmMnOx-rGO catalysts

Reed flower-like SmMnOx and cauliflower-like SmMnOx-rGO catalysts were successfully synthesized by a coprecipitation-coupled solvothermal method for selective catalytic reduction (SCR) of NOx. The NOx conversion of the two catalysts is more than 90% in the temperature range of 75–200 °C, and the N2 selectivity of SmMnOx-rGO is above 90%. Moreover, both of them exhibit more than 62% of resistance to H2O and SO2 at a very low temperature of 100 °C, much superior than the fluffy spherical SmMnOx prepared by coprecipitation method. The strong synergy between Mn and Sm endowed by the flower-like structure contributes to a low degree of crystallization, a high ratio of (Mn3++Mn4+)/Mn, more chemisorbed oxygen species, strong redox ability, and more Lewis acid sites, hence effectively enhancing low-temperature SCR activity and resistance to H2O and SO2. In addition, the decreased ratio of Mn4+/Mn after rGO doping hinders the side reaction of NH3 oxidation, thus enhancing the N2 selectivity of rGO-doped SmMnOx catalyst.

Modeling of extremely ductile behavior of Zr-based bulk metallic glasses under compressive strain paths for solid-state processing

In addition to extremely high strength, manufacturing temperatures of bulk metallic glasses (BMGs) relative to steels are low making them to desired energy saving engineering materials. However, BMGs are significantly brittle at low temperatures. To further increase suitability of BMGs for widespread use, it is essential to understand their plastic deformability (ductility) for high-tech solid-state processes at lowered temperatures. In this work, extremely large deformation behavior (near 80% in compression) of industrially important Zr-based BMGs was investigated. The experimentally measured results aided in the development of an appropriate constitutive model and revealed the micromechanisms affecting the characteristic macroscopic deformation behavior including softening and hardening. The measured and model results showed that the ductility can be significantly improved through chemical composition changes, such as a reduction in the Cu content and an increase in the Zr, Ti, or Be contents. In contrast to previously announced conclusions on the high glass-forming ability (GFA) being the precursors to ductility, formation of sufficiently low degree of crystallization during cooling improved ductility of as-cast specimens under loadings. These observed properties are important in assessing the ability of BMGs for solid-state processing.

Carbonatitic Magma Fractionation and Contamination Generate Rare Earth Element Enrichment and Mineralization in the Maoniuping Giant REE Deposit, SW China

Abstract Carbonatite intrusions host the world’s most important light rare earth element (LREE) deposits, and their formation generally requires extraordinary fertile sources, magmatic evolution, and hydrothermal events. However, carbonatitic magma evolution, particularly the role of fractional crystallization and contamination from silicate rocks in REE enrichment, remains enigmatic. The Maoniuping world-class REE deposit in southwestern China, is an ideal target to decipher magmatic evolution and related REE enrichment as it shows continuous textual evolution from medium- to coarse-grained calcite carbonatite (carbonatite I) at depth, to progressively pegmatoidal calcite carbonatite (carbonatite II) at shallow levels. In both types of calcite carbonatites, four generations of calcite can be classified according to petrographic and geochemical characteristics. Early-crystalizing calcite (Cal-I and Cal-II) are found in carbonatite I and exhibit equigranular and a polygonal mosaic textures, while late calcites (Cal-III and Cal-IV) in carbonatite II are large-size oikocrysts (>0.5 mm in length) with strain-induced undulatory extinction and bent twinning lamellae. All these generations of calcite yield similar, near-chondritic, Y/Ho ratios (26.6–28.1) and are inferred to be of magmatic origin. Remarkably, gradual enrichment of MgO, FeO and MnO from Cal-I to Cal-IV is coupled with a significant increase in REE contents (~800 to 2000 ppm), with LREE-rich and gentle-to-steep chondrite-normalized REE patterns ((La/Yb)N = 3.1–26.8 and (La/Sm)N = 0.9–3.9, respectively). Such significant REE enrichment is ascribed to protracted magma fractional crystallization with initial low degree of fractional crystallization (fraction of melt remining (F) = ~0.95) evolving to late stage (F = 0.5–0.6) by formation of abundant calcite cumulates. Differential LREE and HREE behavior during magma evolution largely depend on separation of phlogopite, amphibole, and clinopyroxene from the carbonatitic melt, which is indicated by progressively elevated (La/Yb)N ratios ranging from 3.1 to 26.8. The four generations of calcite have significantly different C and Sr isotopic compositions with δ13CV-PDB decreasing from −3.28 to −9.97‰ and 87Sr/86Sr increasing from 0.70613 to 0.70670. According to spatial relations and petrographic observations, the relative enrichment of δ13C and depletion in 87Sr/86Sr ratios of Cal-I and Cal-II show primary isotopic characteristics inherited from initial carbonatitic magma. By contrast, the variable Sr and C isotopic compositions of Cal-III and Cal-IV are interpreted as the results of contamination by components derived from silicate wall rocks and loss of CO2 by decarbonation reactions. To model such contamination processes, Raleigh volatilization and Monte Carlo simulation have been invoked and the model results reveal that carbonatitic melt-wall rock interaction requires 40% radiogenic Sr contamination from silicate rocks and 35% CO2 degassing from carbonatitic melt. Moreover, positive correlations between decreasing δ13C values and increasing REE contents, together with bastnäsite-(Ce) precipitation, indicate further REE accumulation during the contamination processes. In summary, alongside REE-rich magma sources, the extent of fractional crystallization and contamination during carbonatitic magma evolution are inferred to be important mechanisms in terms of REE enrichment and mineralization in carbonatite-related REE deposits worldwide.

Characterization of BN interface and its effect on the mechanical behavior of SiCf/SiC composites

The boron nitride (BN) interface of SiC fiber-reinforced SiC matrix (SiCf/SiC) composites was fabricated by chemical vapor infiltration (CVI) using BCl3 and NH3 as precursor. The microstructure and chemical composition of the BN interface were characterized. The influence of the coating thickness on the tensile behavior of SiCf/SiC composites was then evaluated. The BN interface synthesized at 800 °C has a low degree of crystallization and displays a quasi-isotropic microstructure. The ratio of element B to element N is near 1 and the oxygen content is about 10%. Meanwhile, the electron structure of B, N atoms near the SiC fiber surface have more sp2 hybridization state. Increasing the BN interface thickness exerts a critical role in decreasing the interfacial sliding stress which improves the tensile strength and toughness of SiCf/SiC composites. The optimal thickness of the BN interface is about 670 nm and further increasing the thickness exhibits little improvement on the mechanical properties of SiCf/SiC composites.

Highly efficient shrimp shell recovery by solid-state fermentation with Streptomyces sp. SCUT-3

Owing to the rising global production of crustaceans, chitinous waste is being increasingly produced but poorly recycled. The development of new sustainable biorefinery methods is of urgent necessity for replacing traditional chemical recycling methods. A newly isolated Streptomyces sp. SCUT-3 strain, with robust protease secretion and chitin utilization abilities, was used for recycling shrimp shell waste (SSW) in this study. Under optimized conditions, 92.6 % of SSW protein was recovered by 5 d of solid-state fermentation (SSF), of which two-thirds was harvested as free amino acids (FAAs), and one-third as oligopeptides. The deproteinized SSW residue from SSF was easily subjected to calcium extraction, and 92.0 % of calcium was recovered in 30 min using lactic acid. The remaining residue was recovered as chitin products with high purity, a high acetylation rate of 90.5 %, and a low degree of crystallization. Altogether, the Streptomyces SSF-plus-lactic-acid method developed in this study can convert 100 g SSW into 33.6 g FAAs, 16.7 g oligopeptides, 7.4 g calcium (in the form of calcium lactate), and 19.5 g chitin. Analyses of the economic benefits and environmental impact revealed that this method has a low cost (20 %), high profit (10-fold), and a low environmental footprint (1.08 %) compared to traditional-chemical methods, and is superior to other newly developed physicochemical, enzymatic, and biofermentation methods. Higher protease production and constitutive chitinase expression SCUT-3 strains are under-constructed. The possibility of the enhanced super shell degradation strains to realize higher protein yields, synchronous protein, and chitin degradation, or sequential protein and chitin degradation for chitinous waste recycling is discussed. This green sustainable method developed in the study will light the way for the future shell waste recycling industry.

Soot formation in asymmetrical ethylene jet flame-wall interactions

Soot from asymmetrical flame-wall interactions in inclined ethylene jet diffusion impinging flames was studied. The soot morphology, nanostructure and oxidation reactivity were acquired via transmission electron spectroscopy, high resolution transmission electron spectroscopy and thermogravimetric analyzer. Effects of oblique burner angles (θ), Reynolds numbers (Re) and nozzle to plate distances (H) on soot formation and evolution were analyzed. The results showed soot from downhill position presented the higher crystallization degree and the lower oxidation reactivity than soot from uphill position due to the asymmetrical FWI. With θ increased, the promoting effect of the plate on combustion was enhanced at the downhill side and was impaired at the uphill side. The oxidation reactivity of soot with lower crystallization degree from uphill position was improved, while the opposite variation trend was observed from downhill position. Soot from both uphill and downhill positions has the higher carbonization degree and the lower reactivity when Re increased. Soot particles had the shorter fringe length and larger fringe tortuosity and presented the higher reactivity with the augment of H. The reduction of the velocity perpendicular to the wall with the extension of free jet region suppressed soot formation and evolution at uphill and downhill sides.

Enhanced microwave absorbing properties of Y2O3 modified PDC SiCN ceramics with heterogeneous amorphous interface

Polymer derived SiCN ceramics (PDC SiCN) are the key high-temperature matrix materials for structural and stealth integrated ceramic matrix composites (CMC). However, low crystallization degree and homogeneous microstructure of PDC SiCN ceramics results in the lack of effective microwave attenuation mechanism. Hence, a new kind of nonmagnetic metal oxide (Y2O3) was in-situ formed in SiCN ceramics to enhance the conductivity loss as well as the polarization loss. Y2O3 modified PDC SiCN ceramics (SiCN-Y2O3 ceramics) were fabricated by pyrolysis polysilazane with different Y(NO3)3 content at 900 ºC. For the SiCN-Y2O3 ceramic, Y2O3 nanoparticles were dispersed in SiCN ceramic uniformly forming a large number of Y2O3-SiCN heterogeneous amorphous interface, defects and dipole polarization to enhance its microwave absorbing properties. Due to the multiple polarization loss mechanism, SiCN-Y2O3 ceramic with 10 wt% Y(NO3)3 content achieved excellent microwave absorption performance at a wide thickness range with the microwave absorbing efficiency more than 90% in the whole X band, and the RCmin could reach − 50.2 dB at the thickness of 3.5 mm.

Authigenic silica in continental lacustrine shale and its hydrocarbon significance

Taking lake basin shales of the Triassic Yanchang Formation in the Ordos Basin, NW China and the Cretaceous Qingshankou Formation in the Songliao Basin, NE China as research objects, the characteristics and origins of different types of silica in the shales have been studied by means of core observation, thin section identification, cathodoluminescence, X-ray diffraction analysis, scanning electron microscope (SEM), electron probe and rock pyrolysis. The results shows that the origins of silica include felsic mineral dissolution, tuffite devitrification, clay mineral transformation and siliceous mineral metasomatism. The silica formed by feldspar dissolution commonly appears as spots and veins, with low degree of crystallization, and is largely aqueous opal mineral, with an average SiO2 content of 67.2%. Silica formed by devitrification of tuffite mainly occurs in two forms, amorphous silica and authigenic quartz with better crystal shape. The authigenic silica formed during the transformation of clay minerals is embedded in the clay minerals in the form of micron-scale plates and small flakes, or mixed with clay minerals in a dispersed state. The authigenic quartz formed by siliceous mineral metasomatism is in better angular crystal shape, and has an average SiO2 content of 87%. The authigenic siliceous mineral content is positively correlated with the content of terrigenous felsic minerals. The pressure solution of felsic minerals is the main source of authigenic siliceous minerals, followed by the transformation of clay minerals, and the organic matter has some boost on the formation of authigenic silica. The authigenic siliceous materials of different origins have different geological characteristics and occurrence states from terrigenous quartz, which would affect the storage performance, seepage capacity and fracturing effect of continental shale. Although the organic-rich shale has high silica content, different from terrigenous quartz, authigenic silica in this kind of shale mostly floats and disperse in clay minerals, which would have negative effect on the formation of complex fractures in fracturing, fracture support ability after fracturing, and formation of effective seepage channels. Calculating the brittleness index of shale intervals only based on the composition of brittle minerals cannot accurately characterize mechanical characteristics of continental shale oil reservoirs, and would affect comprehensive evaluation and selection of continental shale oil “sweet spots”.

Effects of Mangosteen Peel Phenolic Compounds on Tilapia Skin Collagen-Based Mineralized Scaffold Properties.

A proper valorization of biological waste sources for an effective conversion into composites for tissue engineering is discussed in this study. Hence, the collagen and the phenolic compound applied in this investigation were extracted from waste sources, respectively, fish industry rejects and the peels of the mangosteen fruit. Porous scaffolds were prepared by combining both components at different compositions and mineralized at different temperatures to evaluate the modifications in the biomimetic formation of apatite. The inclusion of mangosteen extract showed the advantage of increasing the collagen denaturation temperature, improving the stability of its triple helix. Moreover, the extract provided antioxidant activity due to its phenolic composition, as confirmed by 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant assays. Mineralization was successfully achieved as indicated by thermogravimetry and scanning electron microscopy. A higher temperature and a lower extract concentration reduced the calcium phosphate deposits. The extract also affected the pore size, particularly at a lower concentration. The X-ray diffraction pattern identified a low degree of crystallization. A high mineralization temperature induced the formation of smaller crystallites ranging from 18.9 to 25.4 nm. Although the deposited hydroxyapatite showed low crystallinity, the scaffolds are suitable for bone tissue applications and may be effective in controlling the resorbability rate in tissue regeneration.

Fabrication and Characterization of Activated Carbon from Phyllostachys edulis Using Single-Step KOH Activation with Different Temperatures

Biomass waste from harvestable output is produced in significant quantities by agricultural and forestry processes and can have detrimental effects on the ecosystem. Therefore, biomass derived from the waste in the environment has been recognized as a potential source for preparing functional materials in recent years. In this study, activated carbon (ACs) was fabricated and characterized from Phyllostachys edulis (Moso bamboo) using single-step potassium hydroxide (KOH) activation at different temperatures (500 °C to 1000 °C). The prepared ACs were characterized for surface morphology, surface area, functional groups and crystallinity using scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, Fourier transform infrared (FTIR) and X-ray diffraction (XRD), respectively. The SEM revealed well-formed pores on the surface of all ACs, while BET analysis revealed the presence of microporous (≤800 °C) and mesoporous (>800 °C) structures. SBET surface area and total pore volume increased with increasing activation temperature, from 434 to 1790 m2/g and 0.2089 to 0.8801 cm3/g, reaching a maximum at 900 °C. FTIR revealed the presence of carbonyl and hydroxyl groups on the surface. XRD showed a dominant amorphous structure and a low crystallization degree in all ACs.

Understanding evolution of the products and emissions during chemical activation of furfural residue with varied potassium salts

Furfural residue is a solid waste produced in manufacturing furfural from biomass like corncob, which can be converted into liquid/gaseous fuel and activated carbon via chemical activation. In this study, in addition the pore structure of activated carbon, the impacts of varied potassium salts (KCl, KOH, K2CO3 and K2C2O4) on the properties of gases and bio-oil formed during activation of Furfural residue was studied. The results showed that the potassium salts suppressed cracking of condensable volatiles into gases, producing more bio-oil at expense of gases. KOH showed the highest activity for cracking, producing the lowest yield of activated carbon (4.8%) without activator with lower degree of crystallization than that K2CO3 and K2C2O4 as activators (20.1% and 26.9%). The activated carbon activated with K2CO3 or K2C2O4 showed the flaky membrane structure packed with varied layers, but not with KOH as the activator. K2C2O4, KOH and K2CO3 as the activators could promote cracking, deoxygenation, dehydrogenation and aromatization reactions, generating abundant micropores, while KCl could not. In addition, K2C2O4 as the activator of furfural residue showed the least energy consumption and environmental impacts, while with KCl was highest. The results herein demonstrated the potential of furfural residue as feedstock for the production of activated carbon and liquid fuels.

Applicability of coal slag for application as packed bed thermal energy storage materials

Refractory materials are considered as the most suitable high-temperature sensible heat storage materials due to their excellent thermo-mechanical resistance and superior thermophysical properties. Unfortunately, refractories are usually too expensive. To reduce the cost of energy storage materials, the recycling of refractory industrial solid wastes into storage materials is becoming increasingly prevalent. The paper innovatively proposes to use the slags from a liquid slagging furnace of a coal-fired power plant in China as packed bed sensible heat energy storage materials. This paper characterizes the chemical compositions and thermophysical properties of three typical coal slags (Fukang coal slag, Fukang coal granulated slag, Hongshaquan coal granulated slag) and evaluates their potentials as storage materials. The results show that the three kinds of coal slags have good thermophysical properties. At 380 °C, the energy storage densities per unit volume of the three materials are 1037 MJ/m3, 986 MJ/m3 and 920 MJ/m3, respectively. Fukang coal slag has good thermal stability and durability and can be directly used for ultra-high temperature energy storage at 1000 °C. Due to the low crystallization degree, the two granulated slags have poor thermal durabilities and need to be processed at high temperatures before using them for energy storage applications.

Novel acyclovir-loaded film-forming gel with enhanced mechanical properties and skin permeability

To develop a novel acyclovir (ACV)-loaded film-forming gel (FFG) with the advantage of providing skin protection and continuous drug release upon application, various FFGs and FFG-films were prepared using drug, chitosan, hydrophilic polymer, plasticizer, lactic acid, water, and ethanol. The mechanical and physiochemical properties were evaluated by film formation time, tensile strength, break elongation, Young's modulus, SEM, FTIR, DSC, and XRD. To identify skin permeation of drug, in vitro skin permeation study was conducted with a Franz diffusion cell using dorsal skin of SD-rat. The ACV-loaded FFG consist of ACV/chitosan/PVP/PEG600/lactic acid/water/ethanol at the weight ratio of 1/1.5/0.5/3/2/40/60 exhibited rapid film formation within about 5 min, resulting in rapid film formation. Furthermore, this ACV-loaded FFG film provided excellent flexibility and showed a low degree of drug crystallization as a result of physicochemical properties evaluation. The ACV-loaded FFG with a high ratio of PEG600 showed a high skin permeability compared to other formulations and significantly improved skin permeability compared to commercial products. Consequently, this novel ACV-loaded FFG would be an effective pharmaceutical product with excellent mechanical properties and skin permeability for herpes labialis.

THE EFFECT OF THERMAL ANNEALING BETWEEN GLASS TRANSITION TEMPERATURE AND CRYSTALLIZATION TEMPERATURE ON DIMENSIONAL ACCURACY OF 3D PRINTED PART

The dimensional accuracy of a 3D printed part affects the function, strength, and assembly process of the part. This study aims to determine the effect of the implementation of thermal annealing process on the dimensional accuracy of Polylactic Acid parts printed by Fused Filament Fabrication. This research uses 32 factorial design methodology with two replications. Two investigated parameters of the thermal annealing process are the annealing temperature and the holding time. The annealing temperature is set between the glass transition temperature and the crystallization temperature, which are 65 °C, 75 °C, and 85 °C. The holding times used are 45 minutes, 60 minutes, and 75 minutes. The response of this research is the dimensional deviation in the X, Y, and Z directions. Based on the experiment result, it was found that the use of higher annealing temperature increases the X, Y, and Z-direction deviations. The analysis result indicates that the use of annealing temperature slightly above the glass transition temperature results in a low degree of crystallization but produces higher dimensional accuracy than annealing temperature below the crystallization temperature. While the use of a holding time of 60 minutes increases the deviation in the X and Z directions but decreases the deviation in the Y direction.

Geochronology and petrogenesis of the Shuizi pyroxenite at Danba, western Yangtze Craton

扬子克拉通西缘在~260Ma发生短期内大规模峨眉山玄武岩溢流喷发。攀西地区发育的镁铁-超镁铁质岩被广泛认为是峨眉山大火成岩省的产物，但在北端松潘-甘孜岩区一直缺乏该类岩石的报道。本文首次报道扬子西缘丹巴水子乡单斜辉石岩的准确年龄，其锆石LA-ICP-MS U-Pb加权平均年龄为260.7±3.3Ma，表明其为峨眉山大火成岩省北端松潘-甘孜岩区镁铁-超镁铁质岩的组成部分。通过与攀枝花钒钛磁铁矿含矿岩体边缘相带苦橄岩和上部相带浅色辉长岩进行锆石微量元素对比显示，水子乡单斜辉石岩具有相近的高氧逸度，其ΔQFM为0~3，Ce_N/Ce_N^*平均为~30，该性质可能同样源自扬子西缘洋壳板片俯冲交代形成的较高氧逸度地幔源区。尽管如此，水子乡辉石岩体并未因高氧逸度而有明显的含钛磁铁矿饱和结晶，可能由其较低结晶分异程度造成。相比之下，攀枝花岩体经历了更高程度的含钛磁铁矿和斜长石分离结晶作用，伴随大规模的钒钛磁铁矿成矿。;Large-scale eruption of Emeishan flood basalt occurred in the western margin of the Yangtze Craton in a short period during~260Ma. Mafic-ultramafic rocks found in the Panxi area are widely considered to be products of the Emeishan Large Igneous Province (ELIP). However, there is a lack of reports on this kind of rocks in the Songpan-Ganzi area in the northern end of the ELIP. This paper first documents a precise age of the Shuizi pyroxenite in the Danba County. The zircon LA-ICP-MS U-Pb weighted mean age is 260.7±3.3Ma, indicating a representative mafic-ultramafic constituent of the northern end of the ELIP in the Songpan-Ganzi area. Comparing zircon trace elements of the Shuizi pyroxenite with those of picrite in the marginal zone and gabbro in the upper zone of the Panzhihua Fe-Ti-V oxide deposit were conducted. It is found that the Shuizi pyroxenite has similarly high magmatic oxygen fugacity, ΔQFM of 0~3 and average Ce_N/Ce_N^* of~30, to the Panzhihua mafic rocks. The high oxygen fugacity for both is considered to be derived from a mantle lithosphere source which had been metasomatized by subducted oceanic slab materials in the western margin of the Yangtze Craton. Although the Shuizi pyroxenite has high oxygen fugacity, there is less obvious Fe-Ti oxide saturation and precipitation here. This could be attributed to its relatively low degree of crystallization and differentiation. In contrast, the Panzhihua mafic-ultramafic intrusion experienced higher degree of titanomagnetite and plagioclase fractional crystallization, accompanied by a massive Fe-Ti-V oxide mineralization.

Triassic calc-alkaline lamprophyre dykes from the North Qiangtang, central Tibetan Plateau: evidence for a subduction-modified lithospheric mantle

AbstractPrimitive lamprophyres in orogenic belts can provide crucial insights into the nature of the subcontinental lithosphere and the relevant deep crust–mantle interactions. This paper reports a suite of relatively primitive lamprophyre dykes from the North Qiangtang, central Tibetan Plateau. Zircon U–Pb ages of the lamprophyre dykes range from 214 Ma to 218 Ma, with a weighted mean age of 216 ± 1 Ma. Most of the lamprophyre samples are similar in geochemical compositions to typical primitive magmas (e.g. high MgO contents, Mg no. values and Cr, with low FeOt/MgO ratios), although they might have experienced a slightly low degree of olivine crystallization, and they show arc-like trace-element patterns and enriched Sr–Nd isotopic composition ((87Sr/86Sr)i = 0.70538–0.70540, ϵNd(t) = −2.96 to −1.65). Those geochemical and isotopic variations indicate that the lamprophyre dykes originated from partial melting of a phlogopite- and spinel-bearing peridotite mantle modified by subduction-related aqueous fluids. Combining with the other regional studies, we propose that slab subduction might have occurred during Late Triassic time, and the rollback of the oceanic lithosphere induced the lamprophyre magmatism in the central Tibetan Plateau.

Effect of annealing on crystallization behavior in Cu15Zr85 amorphous film

The crystallization in Cu15Zr85 amorphous film was studied by using molecular dynamics simulation in a wide annealing temperature region. The effect of annealing temperature on crystallization behavior was evaluated. The degree of crystallization increases firstly and then decreases with the increasing of annealing temperature in Cu15Zr85 amorphous film. A comparison of interior and Surface-A components shows that Surface-A component has higher crystallization rate at low annealing temperature and lower degree of crystallization at high annealing temperature because of faster atomic diffusion. Structural evolution of surface monolayer is unique during annealing. No discernable crystal-like structure is found after annealed in the surface monolayer by directly observing the atomic structure. Surface monolayer with hexagon cluster has low degree of order at high annealing temperature because of the fast liquid-like diffusive motion and improved glass-forming ability.

Preparation of fluorine and carbon co-introduced TiO2 at low temperature with enhanced visible-light degradation performance for 2,4,6-trichlorophenol

Traditional TiO2 photocatalyst has the disadvantages of weak visible-light responsibility, fast combination of photo-generated electron and hole, which significantly degrade its photocatalytic degradation activity. Therefore, fluorine and carbon co-introduced TiO2 was synthesized at a relatively low calcination temperature via a modified sol-gel method, and then be thoroughly characterized to explore the structure-performance relationship. It was found the optimum catalyst FCT-200 prepared at calcination temperature of 200 °C exhibited remarkably enhanced visible-light absorption and restrained photo-generated carrier combination, which should be attributed to the F, C elements co-introduction, lower crystallization degree, and smaller particle size of anatase TiO2. With such advantages, the catalyst therefore demonstrated satisfactory photocatalytic degradation activity for 2,4,6-trichlorophenol (2,4,6-TCP) under visible-light irradiation. The apparent degradation rate reached as high as 0.41971 h−1, almost 42 folds higher than P25. It is anticipated that the fluorine and carbon co-introduced TiO2 photocatalyst presented in this work could provide a new insight into significantly improving the photocatalytic performance of TiO2.

Synthesis of a novel polyester-ether copolymer and its derivatives as antistatic additives for thermoplastic films

Development of antistatic thermoplastic elastomer composites is gaining much interest in scientific and industrial aspects. In this contribution, a novel type of polyester-block-ether copolymer (PEBE), PEBE with ionic liquid (PEBE-IL) and quaternized PEBE (PEBE-Q) were synthesized, characterized and compounded with a commercial bottle grade polyester (PET) resin. It was found that the surface resistivity of the PET composite films was around 109–1010 Ω/sq. The addition of the PEBE copolymers as an antistatic agent into PET matrix resulted in almost 106 times enhancement in surface resistivity compared to neat PET film. Among the PET films with an antistatic agent, it was emphasized that PEBE-IL and ionic liquid doping to PET matrix led to a relatively lower crystallization degree, surface resistivity, contact angle and breaking force with a translucent appearance compared to neat PET film. Furthermore, it was illustrated that antistatic PET films with fine-tune physical, mechanical and morphological properties can be achieved by choosing appropriate antistatic agent type and amount.

Effects of hot pressing temperature on the alignment and phase composition of hot-deformed nanocrystalline Nd-Fe-B magnets

Abstract The magnetic properties, alignment and phase composition of nanocrystalline Nd-Fe-B magnets hot deformed (HD) at 830 °C employing different hot-pressed precursors fabricated at various hot pressing (HP) temperatures were investigated. Both the remanence and coercivity simultaneously increased first and then decreased with the HP temperature from 450 °C to 650 °C. The optimum magnetic properties of HD magnets were obtained at HP temperature of 550 °C with remanence and coercivity of 1.40 T and 924 kA/m, respectively. The usage of the HP temperatures lower than 500 °C was resulted in high porosity and low crystallization degree for hot pressed magnets, causing aggregation of the RE-rich phase and small amount of residual amorphous after hot deformation. This procedure increased the volume fraction of nonmagnetic phase and reduced magnetic properties. Furthermore, the platelet-shaped grains were separated by thick triple junctions, which deteriorated the alignment of grains. When HP temperature was 550 °C, the hot-deformed magnet gained the optimum alignment, and the stacked platelet-shaped grains were separated by smooth thin grain boundary. However, at HP temperature of 650 °C equiaxed coarse grains were dominant instead of platelet-shaped grains in the hot-deformed magnet. The high HP temperature led to apparent grain growth, and then the nucleated grains further grew and were hard to be deformed, developing a poor alignment. A schematic model of the microstructure evolution for hot-deformed magnet is proposed.