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Goethite (FeOOH)-based ore has become attractive to be utilized in ironmaking. As mildly dehydrated to remove its high combined water (CW), it changes to a nanoporous hematite ore. The nanopore contributes a significant increase in ore reduction reactivity due to the nanocontact between iron oxide and reducing agents such as C, CO, or H-2. However, the long dehydration time of goethite ore is still one problem. This study revealed the effect of vacuum condition on the mild-dehydration of goethite-based ore significantly reduces the ore dehydration time. The dehydration is finished within one hour at 300 degrees C under high-vacuum condition (P=1.7 Pa), producing nanoporous hematite ore that is similar to under atmospheric one for 24 h. However, no significant decrease in the dehydration temperature under the high-vacuum condition. In contrast, in-situ heating TEM observation reveals that nanopore generation can occur at low temperatures under ultra-high vacuum conditions (P = 5.6 x 10(-6) Pa). Slit pore generates at low temperatures that then eventually disappear by merging to bigger pores at the higher temperatures.

Morphological control of C60 fullerene using liquefied porphyrins (1 and 2) as the host matrices was explored. Slow evaporation of the solvent of the equimolar mixture of porphyrin and C60 in toluene afforded the porphyrin/C60 composite with a 3:1 molar ratio. The stoichiometric binding behaviors suggest that specific porphyrin-C60 interactions operate the formation of the porphyrin/C60 composites, as corroborated by spectroscopic and thermal properties, and glazing-incidence wide-angle X-ray diffraction. Under the bulk conditions, the conventional thermodynamic advantage of multiple binding cooperativity for molecular recognition is unlikely to explain the stoichiometric binding behaviors. Instead, we propose a size-matching effect on the porphyrin-C60 interaction in the bulk porphyrin matrices, i.e., "supramolecular solvation". The glassy nature of the porphyrin matrices was transmitted to C60 through the specific interaction, and the porphyrin/C60 composites adopted glassy states at room temperature.

Sodium (Na) and lithium (Li) in the silver (Ag) paste cause the potential-induced degradation (PID), while the PID of p-type crystalline silicon (Si) photovoltaic modules is caused by Na in the front cover glass. Some Ag pastes contain these elements to control the firing properties in solar cells fabrication. In order to eliminate the effect of Na and other elements in the front cover glass on PID, PID tests for crystalline Si photovoltaic modules without front cover glass and using cells with various electrode pastes of controlled additive contents were performed. When the Ag paste with Na is used, the shunt resistance decreases and the PID occurs. This phenomenon is similar to that induced by Na in the front cover glass, but, it requires the shorter time duration as compared with the case of Na in the front cover glass. In addition, it is found that Li in the paste also causes the PID equivalent to that by Na in the paste.

Thermal energy storage using phase change materials (PCMs) has been world-widely accepted as an effective technology for energy saving. In this study, Micro-Encapsulated PCMs (MEPCMs) were developed from Al-Si alloys, in which four kinds of Al-Si microspheres with different Al-Si compositions: Al-12%Si, Al-17%Si, Al-20%Si, and Al-30%Si (mass%) were encapsulated by two facile steps for controlling heat storage property. First, boehmite film was formed over the Al-Si microspheres as a precursor shell during boiling in distilled water. Subsequently, the boehmite-coated particles were oxidized by pure oxygen at the high temperatures to ensure the formation of a stable Al2O3 shell. Three different temperatures, 1100 °C, 1150 °C, and 1200 °C, were chosen to study the effect of temperature on the product; the shell morphology, structure, and latent heat storage capacity. Interestingly, the results revealed an increase in MEPCM thermal storage capacity with decreasing Si content and lowering the temperature. The MEPCM melting point was almost identical to its eutectic temperature at ~577 °C, in contrast the larger supercooling was observed for samples with the higher Si content. The cyclic durability of MEPCM was also evaluated through repeated heating and cooling processes in air. The obtained results showed no significant change in both MEPCM structure and thermal storage capacity. It indicated a good repetition durability of MEPCMs oxidized at high temperatures. In conclusion, the Al-Si microencapsulated PCMs appealed great potential as MEPCMs for use in high-temperature thermal energy applications.

Silicon nitride (Si3N4) products with different nanostructure morphologies and different phases for Si3N4 ceramic with high thermal conductivity were synthesized by a direct nitriding method. NaCl and NH4Cl were added to raw Si powders, and the reaction was carried out under a nitrogen gas flow of 100 mL/min. The phase composition and morphologies of the products were systemically characterized by X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. At 1450 °C, the NaCl content was 30 wt %, the NH4Cl content was 3 wt %, and the maximum α-Si3N4 content was 96 wt %. The process of Si nitridation can be divided into three stages by analyzing the reaction schemes: in the first stage (25–900 °C), NH4Cl decomposition and the generation of stacked amorphous Si3N4 occurs; in the second stage (900–1450 °C), NaCl melts and Si3N4 generates; and in the third stage (>1450 °C), α-Si3N4 → β-Si3N4 phase change and the evaporation of NaCl occurs. The product...

Cerium-doped yttrium aluminum garnet (YAG:Ce) as a yellow phosphor for white light-emitting diodes (LEDs) was synthesized via a facile combustion method using Y2O3, CeO2, Al2O3, Al, and NaClO4 as raw materials. The combustion synthesis approach utilizes the strong exothermic oxidation of aluminum to realize a self-sustaining reaction. In this study, we investigated the effects of the ratios of Al2O3 to Al, fluxes, and coprecipitated materials as raw materials on the luminescence properties of the synthesized YAG:Ce phosphors. When the amount of Al2O3 x is varied, the combustion reaction proceeds at x

Development of highly durable phase change materials (PCMs) above 500 °C is essential in future high-temperature thermal energy storage systems. In this study, we report the fabrication of microencapsulated PCM (MEPCM) microspheres with high-temperature stability and cycling durability over 3000 cycles. The MEPCM consists of an Al–Si alloy core (Al–25 wt% Si; melting point of 577 °C) and a self-repairing Al2O3 shell. The uniform and highly durable Al2O3 shell is processed in three indispensable steps. Firstly, a boehmite treatment in an Al(OH)3 turbid solution under an optimal pH value of 8 is used for the formation of AlOOH and Al(OH)3 shell precursors. Secondly, additional Al(OH)3 is further precipitated on the surface to enhance the formation of a thicker shell. Finally, a stable and self-repairing two-phase (α-Al2O3 and θ-Al2O3) Al2O3 shell is formed by heat-oxidation in an O2 atmosphere. The surface morphology, crystal structure of the shell, thermal durability, cycling stability and the shell formation mechanism are carefully investigated. The newly introduced boehmite and precipitation pre-treatments under optimal conditions can reinforce the formation of a thick and highly compact shell with small α-Al2O3 and θ-Al2O3 grains, which are beneficial to disperse the thermal stress during high-temperature cycling and restrain crack propagation. The excellent achievement of durability over 3000 cycles can promote the practical applications of the MEPCM for high-temperature thermal storage, for example, it can be applied to the thermal storage system of a concentrated solar power plant for more than 6 years based on the reported durability.

Yellow Ca-α-SiAlON:Eu 2+ phosphors for white light-emitting diodes (LEDs) were synthesized by a facile combustion synthesis method using CaO, Eu 2 O 3 , α-Si 3 N 4 , Si, and Al as raw materials. Ca concentrations and diluent ratios were optimized to improve their luminescence properties. The lattice constant and luminescence properties improved as x increased from 0.4 to 1.2 in Ca x Si 12 − (m+n) Al m+n O n N 16−n :Eu 0.06 . The optimum value was x = 1.2. Scanning transmission electron microscopy combined with energy dispersive X-ray analysis detected segregation of Ca and Eu at grain boundaries, which decreased luminescence behavior in the x = 1.4 sample. The influence of Si and Si 3 N 4 diluents was investigated by varying the diluent ratio φ = (CaO + Eu 2 O 3 + α-Si 3 N 4 )/(CaO + Eu 2 O 3 + α-Si 3 N 4 + Al + Si). Changes in temperature and flame propagation speed were measured during combustion synthesis using two thermocouples. When φ was less than 0.5, the combustion temperature exceeded 1600 °C and the synthesized material contained an amount of the high-temperature β-SiAlON phase. At φ > 0.7, the reaction temperature fell below 1200 °C, and unreacted raw materials remained. The optimum value of φ was 0.6. The internal quantum efficiency of the product synthesized at x = 1.2 and φ = 0.6 was approximately 35% under 450-nm excitation. According to electron probe X-ray microanalysis, composition varied within individual synthesized particles, which may explain the decrease in emission behavior relative to a commercial product.

This study investigates the combustion synthesis of AlN fibers using an NH4Cl additive and reports the effects of Al particle size (3, 30, and 180 µm) and N2 pressure (0.10, 0.25, and 0.50 MPa) on the purity and morphology of AlN fibers. The combustion temperature was directly measured during the synthesis to elucidate the formation mechanism of the AlN fibers. The phase purity and morphology of the products were studied using X-ray diffraction and scanning electron microscopy, respectively. When the particle size of Al was reduced from 180 to 3 µm, the purity of the AlN product increased significantly owing to the large reaction area, which increased the combustion temperature. Furthermore, lower N2 pressures enhanced the formation of AlN nanofibers due to the accelerated gasification of Al. The optimum values of the particle size of Al and the N2 pressure for the formation of high-purity AlN nanofibers were found to be 3 µm and 0.10 MPa, respectively.

Three-dimensional (3D) distributional analysis of individual dopant atoms in materials is important to development of optical, electronic, and magnetic materials. In this study, we adopted through-focus high-angle annular dark-field (HAADF) imaging for 3D distributional analysis of Eu dopant atoms in Ca-α-SiAlON phosphors. In this context, the effects of convergence semi-angle and Eu z-position on the HAADF image contrast were investigated. Multi-slice image simulation revealed that the contrast of the dopant site was sensitive to change of the defocus level. When the defocus level matched the depth position of a Eu atom, the contrast intensity was significantly increased. The large convergence semi-angle greatly increased the depth resolution because the electron beam tends spread instead of channeling along the atomic columns. Through-focus HAADF-STEM imaging was used to analyze the Eu atom distribution surrounding 10nm cubes with defocus steps of 0.68nm each. The contrast depth profile recorded with a narrow step width clearly analyzed the possible depth positions of Eu atoms. The radial distribution function obtained for the Eu dopants was analyzed using an atomic distribution model that was based on the assumption of random distribution. The result suggested that the Ca concentration did not affect the Eu distribution. The decreased fraction of neighboring Eu atoms along z-direction might be caused by the enhanced short-range Coulomb-like repulsive forces along the z-direction.

Latent heat storage (LHS) technology employing phase change materials (PCMs) has received great attention as an alternative to conventional solid sensible heat storage (SHS) for future high-temperature energy utilisation systems. In this study, we report the synthesis of a core-shell type microencapsulated PCM (MEPCM) consisting of Al-25 wt% Si microspheres (mean diameter of 36.3 μm and melting temperature of 577 °C) as the core (PCM) and Al2O3 as the shell. The MEPCM was prepared in two steps involving (1) the formation of an AlOOH precursor shell on the PCM microspheres by a hydroxide precipitation process in hot water and (2) heat-oxidation treatment in an O2 atmosphere to form a stable Al2O3 shell. In particular, the effects of heat-oxidation temperature on the shell morphology, shell crystal structure, mechanical strength, heat capacity, and cyclic durability of the prepared MEPCMs were examined. The resultant MEPCM is composed of a stable α-Al2O3 shell and Al-25 wt% Si core with an effective void inside the core to allow for volume expansion of the PCMs during solid-liquid phase transitions. The heat capacity measured for this material is five times higher than that of conventional solid SHS materials. Additionally, the MEPCM exhibits excellent durability up to 300 heating and cooling cycles under oxygen atmosphere. Consequently, it can potentially be used in the next-generation LHS-based high-temperature thermal energy storage and transportation systems.

A series of surface-doped LiMn2O4 samples modified by a Li2CuO2-Li2NiO2 solid solution were synthesized using a simple and facile sol-gel method to achieve the enhanced cycling performance, especially at elevated temperatures. The corresponding phase structure and morphology were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The modified layer on the surface of LiMn2O4 particles, featuring a LiNi delta Mn2-delta O4-like phase, together with a Li2CuO2-Li2NiO2 solid solution, as confirmed by XRD and transmission electron microscopy (TEM), plays a key role in alleviating the dissolution of manganese, thus enhancing the cycling performance and rate capability relative to bare LiMn2O4. The 0.5 wt.%-modified LiMn2O4 sample delivers a discharge capacity of 113 mAh g(-1), and a capacity retention of 93.2% following 300 cycles at 1C and 25 degrees C, which is higher than the values of 96 mAh g(-1) and 81.2% for bare LiMn2O4. In addition, at 55 degrees C, a capacity retention of 81.2% at 1C is obtained for the 0.5 wt.%-modified LiMn2O4 sample after 200 cycles, compared to 70.0% for bare LiMn2O4. Modifying the surface of the latter by a LiNi delta Mn2-delta O4-like phase mixed with a Li2CuO2Li2NiO2 solid solution, is an effective strategy for improving electrochemical properties.

In this paper, a novel method is proposed to produce MnO/carbon composites, in which the MnO nanoparticles were embedded into a porous carbon matrix, by a single-step nitrate-cellulose combustion synthesis. The composition, structure and morphology of the composites were characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and scanning/transmission electron microscopy. The composites were used as lithium ion battery anodes to evaluate their electrochemical properties. The MnO/carbon composite with a proper carbon content showed enhanced cycling performance and capacity retention, which delivered a reversible capacity of 561 mAh g −1 after 90 cycles at 0.2 A g −1 . The easy production and good electrochemical properties enables the composite to be a possible candidate as an anode alternative for high-performance lithium ion battery.

In order to investigate the influence of the difference in module structure on the degradation of the solar cell, two kinds of different solar modules were fabricated, and a high temperature and high humidity test was carried out and the degradation mode was compared by electrical characteristics and electroluminescence inspection. Although degradation of output occurred in both modules, different degradation modes were confirmed by electroluminescence images. It is assumed that the difference in degradation mode between these modular structures is due to the difference in concentration distribution inside the module of moisture intruded into the module and acetic acid generated from the encapsulant inside the module.

Because abnormal grain growth (AGG) degrades mechanical properties of industrial polycrystalline materials such as steel, understanding and controlling AGG are important. In this study, AGG of Al-Nb-microalloyed low-carbon steel was investigated at 1100°C using in-situ scanning electron microscopy-electron backscatter diffraction (SEM-EBSD). Owing to the pinning particles of AlN and Nb(C,N), fine austenite grains formed initially, and AGG appeared owing to the dissolution of the pinning particles at high temperatures. Relatively large grains invaded the surrounding smaller grains with a size ratio of approximately 0.3, resulting in AGG. We developed the in-situ observation method to investigate the AGG of the carburization process using a diffusion couple of high- and low-carbon steels. The carbon diffusion into the low-carbon steel from the high-carbon steel enhanced the grain growth of the low-carbon steel. Although the detailed mechanism is still unclear, we clearly showed that carburization can reduce the pinning force. When focusing on the misorientation of the grain boundary, grain boundaries with misorientation angles of 50–59° remained during AGG, which is explained by their lower mobility owing to their lower grain boundary energy. These results suggest that the difference in grain-boundary mobility can induce duplex grain growth with a bimodal distribution, resulting in AGG.

Brownmillerite-structured Ca2AlMnO5 is inexpensive and capable of rapid oxygen storage and release. This study focused on improving the oxygen storage/release rate of Ca2AlMnO5, which is essential for its application in practical oxygen production systems. Two approaches were investigated for improving the oxygen-trapping ability of Ca2AlMnO5: heat treatment for 2 h and 24 h after solution combustion synthesis (SCS) and the addition of Pt nanoparticles as a catalyst. Noticeably, crystalline Ca2AlMnO5 was formed after heat treatment at 1250 °C for at least 2 h. For the 2-h heat treatment, the average particle size of Ca2AlMnO5 was 11.4 μm, while that for the 24-h treatment was 18.9 μm. This reduction in the particle size increases the oxygen storage/release rate because of the relatively short diffusion distance within the particles. The oxygen storage rate increased with the addition of Pt nanoparticles because the nanoparticles were distributed across the surface and acted as catalyst. This catalyst accelerated the oxygen-evolution reaction by activating the surface reactions between oxygen ions and the Ca2AlMnO5 particles. The short 2-h heat treatment prevented the Pt nanoparticles from aggregating. When the Pt nanoparticle addition was implemented in combination with the 2-h heat treatment, the storage and release rates were drastically improved, i.e., by 2.5 and 6.1 times, respectively, compared with the sample after 24-h heat treatment without Pt nanoparticles. The oxygen storage/release rate remained constant even after repeated use at 550 °C, for over 25 cycles. Furthermore, Ca2AlMnO5 suffered no surface damage, and none of the Pt nanoparticles re-agglomerated after this test, further indicating the durability of the treated material.

In this study, Ca-α-SiAlON:Eu2+ yellow phosphors for white light-emitting diodes (LEDs) were synthesized via a facile combustion synthesis method by using CaO, Eu2O3, Si, and Al as raw materials, while NaCl and Si3N4 were utilized as diluents to contain the combustion temperature. The concentration of Eu was varied, and the resulting changes in phase purity, photoluminescence properties, and thermal quenching were investigated. We observed that the increase in lattice constant depended on the amount of Al, while the Ca sites were partially substituted by Eu ions. The synthesized Ca-α-SiAlON:Eu2+ powders exhibited emission wavelength at 556–560 nm and high thermal stability, revealing high potential for application in white LEDs.

This study optimizes the dehydration temperature of goethite to control pore morphology. The pore morphology was characterized by using transmission electron microscopy and the nitrogen adsorption method. When the goethite was dehydrated at 200–250°C, slit-like pores with a width lesser than 2 nm were formed along the [010] direction. These slit-like pores changed to spherical micropores (300–500°C), and eventually disappeared (600–800°C). Compared to the synthetic goethite, natural goethite has a lower crystallinity and smaller primary particle size of under 100 nm. The natural goethite before dehydration contained 4 nm pores as cracks that remained even after heating to 800°C. In the case of natural goethite, the optimum dehydration temperature for higher surface area and pore volume was 350°C, which was higher than that of 250°C for the synthetic goethite.

The surface of spinel LiMn2O4 is modified with different quantities of a Mn4+-rich phase prepared by a facile sol-gel method to improve electrochemical properties at elevated temperatures. Impurity-free and uniform morphologies for the LiMn2O4 particles are demonstrated from the X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The Mn4+-rich phase modified on the surface of the LiMn2O4 alleviates the dissolution of manganese in the electrolyte, thus improving the cycling performance and rate capability relative to the bare LiMn2O4. 1 wt.%-modified LiMn2O4 delivers a capacity retention of 92.7% and a discharge capacity of 113.5 mAh g−1 after 200 cycles at 1C and 25 °C, compared with that of 83.1%, and 100.8 mAh g−1 for the bare LiMn2O4. In addition, after 100 cycles, a capacity retention of 88.6% at 1C is achieved for 1 wt.%-modified LiMn2O4 at 55 °C, which is higher than the 76.0% for the bare LiMn2O4. Furthermore, this sample shows the best rate capability among all samples. The Mn4+-rich phase is an appropriate candidate for modifying surfaces to suppress dissolution of manganese, thereby improving the electrochemical properties of LiMn2O4.

In this study, a Sn–C composite material as anode material for lithium ion batteries was fabricated via MgO template-assisted solution combustion synthesis, in which the starting material was a gel containing Sn(NO 3 ) 2 , glycine (C 2 H 5 O 2 N) as the carbon source, and Mg(NO 3 ) 2 ·6H 2 O for the template. After the combustion reaction, the generated MgO was removed from the carbon, and the Sn nanoparticles were dispersed into a porous carbon structure during the carbon reduction of SnO 2 under calcination in N 2 . The effects of ratios of glycine ( n ) and MgO ( m ) on the material phase, morphology, carbon content, and electrochemical properties were mainly investigated. At glycine ( n ) ratios of 2 and 3, the SnO 2 phase was not fully reduced to Sn. With n > 3, a composite material of metallic Sn nanoparticles and carbon was synthesized, in which the ratio of carbon increased with increasing n . With increasing m , the porosity of the particles increased, resulting in enhanced cyclic stability owing to the buffer space provided by the porous structure of carbon. The composite material obtained at n = 4 and m = 4 exhibited the highest reversible capacity of 588 mA h/g after 100 discharge/charge cycles at a current rate of 0.5 A/g as compared to the 269 mA h/g observed for n = 4 and m = 2.

In this study, MnO nanocrystals incorporated in a N-containing carbon matrix were fabricated by the facile thermal decomposition of manganese nitrate-glycine gels. MnO/C composites with different carbon contents were prepared by controlling the initial ratio of manganese to glycine. The composition, phase structure and morphology of the composites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning and transmission electron microscopy, and thermogravimetric analysis. The results indicated that MnO nanocrystals were uniformly embedded in the N-doped carbon matrix. The carbon matrix could effectively enhance the electrical conductivity of MnO and alleviate the strain arising from the discharge/charge cycling. The composite materials exhibited high discharge/charge capacities, superior cycling performance, and excellent rate capability. A high reversible capacity of 556 mA h g(-1) was obtained after 110 cycles of discharging and charging at a current rate of 0.5 A g(-1). Even at a high current rate of 3 A g(-1), the sample still delivered a capacity of around 286 mA h g(-1). The easy production and superior electrochemical properties enables the composites to be a promising candidate as an anode alternative for high-performance lithium-ion batteries.

In this paper, we describe the glycine–nitrate-based solution combustion synthesis of SrTiO3 nanoparticles. The effects of the fuel ratio, φ, and washing treatment by HNO3 on the size, morphology, and crystalline structure of the synthesized particles were investigated. The photocatalytic activity of the final samples was also evaluated by measuring the photodegradation of methylene blue. The samples, which were calcined at 1000 °C for 10 h after combustion synthesis, were mainly SrTiO3. When φ was increased, the number of pores in the sample was increased because of the increase in volume of ejected gas. Additionally, the initial particle size decreased with increasing φ because glycine functioned not only as a fuel but also as a dispersant and stabilizer. After washing in a HNO3 solution, the porous structure decomposed to particles with high crystalline structure. The photocatalytic activity of SrTiO3 was significantly improved by HNO3 washing owing to the elimination of impurities, the increase in surface area, and the uncovering of the surface that consisted of (100) planes.

Urchin-like CoO and Co 3 O 4 hollow structures with potential use as anodes in lithium ion batteries were synthesized via the facile thermal decomposition of precipitated amorphous cobalt carbonate hydroxide under either Ar or air. The morphology and, consequently, electrochemical properties of the samples were highly dependent on the precipitation temperature. The cobalt oxides, as derived from precursors that were obtained at room temperature, exhibited superior activity to those obtained at 50 °C and 80 °C because of their unique nanosized architecture. Meanwhile, CoO samples demonstrated much better cyclability and rate capability than Co 3 O 4 samples, as they exhibited much higher coulombic efficiency and lower hysteresis for lithium insertion/extration. The curved, short, and closely entangled nanowires of CoO sample, which was derived from room temperature precursor, yielded excellent electrochemical performance. The sample displayed a high reversible capacity of about 850 mAh g −1 at a current density of 500 mA g −1 , a good stability through 50 cycles with a high coulombic efficiency of about 98%, and a high rate capability of 610 mAh g −1 even at a rate of 3000 mA g −1 .

An amorphous iron oxide–carbon composite has been fabricated through an effective, inexpensive, and scalable method employing solution combustion synthesis. Amorphous iron oxide nanoparticles with diameters of about 5 nm were synthesized and uniformly embedded in a dense carbon matrix. The synthesized composite exhibits enhanced cyclability and rate capability, showing a high reversible capacity of 687 mA h g − 1 after 200 discharge/charge cycles at a current rate of 0.5 A g − 1 , compared to the 400 mA h g − 1 observed for Fe 2 O 3 nanoparticles. This enhanced performance was retained despite more demanding conditions, delivering a high capacity of about 525 mA h g − 1 and a nearly perfect coulombic efficiency even after 400 cycles at 1 A g − 1 . The easy production and superior electrochemical properties of this composite suggest that it is a promising material for use as an anode material in high performance lithium ion batteries.

A convenient method for coating titanium dioxide (TiO 2 ) by Au nanoparticles (AuNPs) is demonstrated in solution plasma to improve the photocatalytic activity of TiO 2 . AuNPs from a metallic Au electrode were bonded to the surface of a commercial TiO 2 powder, which acted as a catalyst support, with the reaction taking place in an electrolyte solution. The effect of diverse plasma conditions on the size and productivity of the AuNPs was investigated initially to provide a reference in the absence of TiO 2 . At 290 V, “ partial plasma ” was attained, with only a weak light emission surrounding the Au electrode. Conditions then evolved to “ full plasma ”, with a strong orange emission at 330 V. Partial or full status was maintained for 1 h at 300 and 400 V, respectively. At the transition to full, the AuNP particle size increased from 3.72 to 6.09 nm and the productivity increased dramatically from 0.025 to 0.87 mg h − 1 mm − 2 . Stronger plasma very efficiently synthesized AuNPs, and therefore, it was adopted for further study. AuNP–TiO 2 combinations were formed by applying 400 V to a TiO 2 -dispersed solution. In these experiments, TiO 2 coated with AuNPs was synthesized; these combinations of AuNP–TiO 2 had 0.44 mol% of Au. The photocatalytic activity of AuNP–TiO 2 was investigated by measuring the degradation of Rhodamine B (RhB). Under UV irradiation, the AuNP–TiO 2 particles removed up to 95% of the dye in 70 min. Commercial TiO 2 achieves values closer to 85%. The results thus raise the possibility that solution plasma methods can be generalized as a means for achieving catalysis-enhancing coatings.

Single-phase, high-purity nanosized LiMn 2 O 4 powders, which are employed as cathode materials for lithium-ion batteries, were produced by solution combustion synthesis using glycine, sucrose, and nitrate, followed by calcination. Phase structure and morphology of the powders were characterized by X-ray diffraction and scanning electron microscopy. The electrochemical performance was measured by galvanostatic charge–discharge cycling in a voltage range of 3.2–4.4 V. The analysis of yield, morphology, and electrochemical performance mainly focused on the influence of different glycine/sucrose ratios. Compared to the sample obtained using 100% glycine, the yields of powders obtained by adding sucrose to the fuel were remarkably improved, from around 50% to over 90%. The highest discharge capacity at 1 C was obtained for the sample with 2% added sucrose, which retained a capacity of 116.6 mAh/g after 80 cycles.

A series of LiBixLaxMn2−2xO4 (x = 0, 0.002, 0.005, 0.010, 0.020) samples were synthesized by solution combustion synthesis in combination with calcination. The phase structure and morphology of the products were characterized by X-ray diffraction, scanning electron microscopy, and transition electron microscopy. The results demonstrated that a single-phase LiMn2O4 spinel structure was obtained for the LiBixLaxMn2−2xO4 (x = 0, 0.002, 0.005) samples, whereas impurities were observed for the LiBixLaxMn2−2xO4 (x = 0.010, 0.020) samples as a result of the doping limit. The electrochemical properties were investigated by galvanostatic charge–discharge cycling and cycling voltammetry in a voltage range of 3.2–4.4 V. The substitution of Mn3+ by equimolar Bi3+ and La3+ could significantly improve the structural stability and suppress the Jahn–Teller distortion, thereby resulting in improved electrochemical properties for the Bi and La co-doped samples in contrast with the pristine LiMn2O4 sample. In particular, the LiBi0.005La0.005Mn1.99O4 sample delivered a high initial discharge capacity of 130.2 mA h g−1 at 1C, and following 80 cycles, the capacity retention was as high as 95.0%. Moreover, it also presented the best rate capability among all the samples, in which a high discharge capacity of 98.3 mA h g−1 was still maintained at a high rate of 7C compared with that of 75.8 mA h g−1 for the pristine LiMn2O4 sample.

This work investigates the optimum experimental conditions required for the synthesis of Sn nanoparticles (Sn-NPs) via surfactant-free direct-current electrolysis using KCl as the electrolyte. Metallic Sn wire was used as a cathode, which was melted by the local concentration of current upon the application of a direct-current voltage. The effect of electrolyte concentration was analyzed by varying the concentration from 0.01 to 1.0 M, under constant electric power of 40 W. Results indicated that the applied voltage required for plasma generation increased with a decrease in the electrolyte concentration and the particle size decreased at high applied voltage with low electrolyte concentration; particles with a mean diameter of 258.5 nm formed at 0.05 M. However, coarse Sn 6 O 4 (OH) 4 crystals were precipitated at a concentration of 0.01 M. Therefore, the optimum concentration required for the formation of smaller particles was determined to be 0.05 M. Subsequently, the effect of voltage was analyzed by varying the applied voltage from 70 to 190 V. As a result, the effective production energy of 45 W h/g was obtained at voltages ranging from 110 to 130 V.

Carbon deposited by tar decomposition within pores of iron ore exhibited a high reactivity during the reduction reaction. The structure of porous low-grade ore was investigated in detail using transmission electron microscopy (TEM); a layered structure with 3 nm diameter pores was observed after dehydration, because of the removal of the hydroxide (OH) group from FeOOH. This pore size was deemed to be appropriate for tar decomposition and resultant carbon deposition. However, it was found that not all pores were filled with carbon. The TEM image showed that some of the deposited carbon partially blocks the pores, which negatively affects the carbon deposition process. In addition to the ore structure, the type of carbon deposited was also successfully evaluated using Raman spectroscopy and found to consist of two main peaks, G and D. The position of the G peak was found to shift slightly, indicating that the sp3 content was reduced at elevated temperatures because of a greater degree of graphitization. Th...

We have adopted a solution plasma synthesis for preparing Sn nanoparticles (Sn-NPs) directly from metallic Sn electrode. The Sn-NPs were synthesized in the presence of the surfactant, cetyltrimethylammonium bromide (CTAB), and the effect of the concentration of CTAB on the Sn-NPs was investigated. Without CTAB addition, SnO plates were precipitated. Sn-NPs with less than 200 nm were synthesized at a high concentration of 200 × 10 −6 g ml −1 of CTAB. Electrochemical properties of SnO plates and Sn-NPs were analyzed for use as an anode material in Li-ion batteries. A composite of Sn-NPs and graphite enhanced the cyclic stability owing to the buffer space provided by the graphite for volume expansion. In the case of the 30 wt% loaded Sn-NPs, the capacity was measured to be 414 mA h g −1 after 20 cycles.

In this work, fine powders of spinel-type LiMn 2 O 4 as cathode materials for lithium ion batteries (LIBs) were produced by a facile solution combustion synthesis using glycine as fuel and metal nitrates as oxidizers. Single phase of LiMn 2 O 4 products were successfully prepared by SCS with a subsequent calcination treatment at 600–1000 °C. The structure and morphology of the powders were studied in detail by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The electrochemical properties were characterized by galvanostatic charge–discharge cycling and cyclic voltammetry. The crystallinity, morphology, and size of the products were greatly influenced by the calcination temperature. The sample calcined at 900 °C had good crystallinity and particle sizes between 500 and 1000 nm. It showed the best performance with an initial discharge capacity of 115.6 mAh g −1 and a capacity retention of 93% after 50 cycles at a 1 C rate. In comparison, the LiMn 2 O 4 sample prepared by the solid-state reaction showed a lower capacity of around 80 mAh g −1 .

The austenite (gamma) structure reversely transformed from martensite in Fe-0.55C mass% C alloy was investigated at high temperatures using in-situ an electron backscatter diffraction (EBSD) method. When the heating rate was varied, a rapidly heating produced fine gamma grains, in contrast, a slow heating induced coarse gamma grains having the same crystal orientations as those of the prior gamma grains; known as "gamma memory". The most likely mechanism for the gamma memory could be variant restrictions owing to cementite (theta). To investigate the effect of theta on the gamma memory, the sample was tempered at 700 degrees C for 24 h and theta was precipitated. The tempered sample exhibited the gamma memory irrespective of the heating rate. To clarify the origin of the gamma memory, we focused on the reversely transformed gamma formed adjacent to the theta and directly observed the orientation relationships (ORs) using the in-situ EBSD. A crystallographic analysis on the between neighboring ferrites (alpha), theta, and gamma revealed the existence of Kurdjumov-Sachs OR between gamma and two alpha (alpha 1 and alpha 2), Isaichev OR between alpha and theta, and Pitsch OR between theta and gamma. In the all possible combinations, the reversely transformed gamma satisfying the K-S OR for two alpha variants was limited to four variants. The theta variant satisfying the Isaichev OR for alpha 1 and alpha 2 was limited to one variant, which was close to one of the four variants by Pitsch OR, which suggests the gamma memory is due to these variant restrictions among alpha-theta-gamma.

We investigated the dopant distribution in Ca-doped α-SiAlON by using high-angle annular dark-field scanning transmission electron microscopy and a multi-slice image simulation. Our results showed that the electron wave propagated by hopping to adjacent Si(Al) and N(O) columns. The image intensities of the Ca columns had wider dispersions than other columns. To estimate the Ca distribution in the bulk material, we performed a Monte Carlo atomic simulation of the α-SiAlON with Ca dopants. A model including a short-range Coulomb-like repulsive force between adjacent Ca atoms reproduced the dispersion of the intensity distribution of the Ca column in the experimental image.

Single-crystalline tin oxide (SnO) plates were synthesized by a solution plasma technique using an Sn wire. In the experiments, we applied a voltage of 400 V in a 0.001 M K2CO3 solution. The effects on the products of the solution temperature, the use of surfactants, and the cooling rate were investigated. A solution temperature above 95.0 °C was effective for producing single-crystal SnO plates. The addition of poly(vinyl alcohol) (PVA) significantly stabilized the Sn6O4(OH)4 octahedrons. In the case of cetyltrimethylammonium bromide (CTAB) addition, SnO and Sn crystals with plate crystal, particle, and rod morphologies were formed. Quenching the solution affected the product size. Faster cooling rates reduced the size of the SnO plates. SnO plates with (001) plane faces precipitated from Sn(OH)3 − ions to form plate-like crystals as a result of the difference in the growth rates at each plane.

We synthesized ZnO nanoflowers using a solution plasma. We examined the effects of the applied voltage and the concentration of the electrolyte on the morphology of the products. In the experiments, the zinc wire (cathode) was immersed in an electrolysis solution of K2CO3 (concentration: 0.01 to 5.00 M) and was electrically melted by a glow discharge at different voltages ranging from 42 to 200 V. The results revealed that the products were nanoflowers having many nanorods (size

Because of the easy massproduction, synthesis of metallic nanoparticles from a solution plasma is an attractive method. However, a solution plasma produces a highly inhomogeneous electric field via transition to full-plasma, and the products are partially oxidized and agglomerated, with a wide size-distribution. Here, we show a simple method of suppressing oxidation of products. An electrode tip was shield by a glass tube and a voltage of up to 180 V was applied with the electrolyte of 0.1 M NaOH solution. Significantly, the edge-shield was quite effective for maintaining partially glow discharge. The results were (1) surface temperature of the electrode less than 100°C, (2) main phase of metallic nickel evaluated by XRD, and (3) nanoparticles of an average size of 220 nm. These results showed the potential for an application to the production of nanoparticles.

Silicon anodes have attracted considerable attention for their use in lithium-ion batteries because of their extremely high theoretical capacity; however, they are prone to extensive volume expansion during lithiation, which causes disintegration and poor cycling stability. In this article, we use two approaches to address this issue, by reducing the size of the Si particles to nanoscale and incorporating them into a carbon composite to help modulate the volume expansion problems. We improve our previous work on the solution-plasma-mediated synthesis of Si nanoparticles (NPs) by adjusting the electrolyte medium to mild buffer solutions rather than strong acids, successfully generating Si-NPs with

Cu 2 ZnSnS 4 films were grown on Si (100) by vacuum evaporation using elemental Cu, Sn, S and binary ZnS as sources. X-ray diffraction patterns of films grown at different substrate temperatures indicated that polycrystalline growth was suppressed and the orientational growths were relatively induced in a film grown at higher temperatures. Tetragonal structure of Cu 2 ZnSnS 4 films was confirmed by studying RHEED patterns. The existence of c -axis ([001] direction) growth, two kinds of a -axis (〈100〉 direction) growth and four kinds of {112} twins which can be classified as two symmetrical pairs is proposed. Broad emissions at around 1.45 eV and 1.31 eV were observed in the photoluminescence spectrum measured at 13 K.