NaCl Flux Research Articles

Flux synthesis and growth mechanism of Na 0.5MnO 2 whiskers

We report here the preparation of Na 0.5MnO 2 whiskers from Mn 2O 3 and Na 2CO 3 in NaCl flux, where NaCl also acted as a reactant along with Na 2CO 3. As a result, the reaction system became more homogeneous, and meanwhile Mn 2O 3 reacted with NaCl more slowly than Na 2CO 3, finally leading to the crystals of high crystallinity and purity. Moreover, large Na 0.5MnO 2 whiskers (0.01×0.01×0.1 mm 3) can be obtained in absence of Na 2CO 3 due to the slow reaction rate. A detailed study of Na 0.5MnO 2 whisker growth process revealed that a layer-to-tunnel structure transformation occurred accompanying anisotropic growth and oriented aggregation.

Effects of Particle Surface Areas and Microstructures on Photocatalytic H2 and O2 Production over PbTiO3

The visible-light photocatalyst PbTiO3 was prepared in molten NaCl and PbO fluxes using 0.5:1–20:1 flux-to-reactant molar ratios by heating to 1000°C for a duration of 1 h. Yellow-colored powders were obtained in high purity, as confirmed by powder X-ray diffraction and exhibited a bandgap size of ∼2.75 eV as determined by UV–Vis diffuse reflectance measurements. Roughly spherical and cubic shaped particles with homogeneous microstructures were observed with sizes ranging from ∼100 to 6 000 nm, and surface areas ranging from 0.56 to 2.63 m2/g. The smallest particle-size distributions and highest surface areas were obtained for the 10:1 NaCl flux molar ratio. By comparison, solid-state preparations of PbTiO3 particles exhibit no well-controlled sizes or microstructures. The water-splitting photocatalytic activities of the PbTiO3 particles were evaluated in visible light (λ>420 nm), and yielded maximum rates of 27.4 μmol·H2·(g·h)−1 for the PbTiO3 prepared using a 1:1 PbO molar ratio and 183 μmol·O2·(g·h)−1 for the solid-state prepared sample. The rates were inversely correlated with the particle surface areas. The relationship between particle morphology and photocatalytic activity provides important insights into understanding the origins of photocatalysis in metal-oxides.

The Research of by Blend and Flux Method SrFe<sub>12</sub>O<sub>19</sub> Magnetic Particle Preparation and Magnetic Properties

According to the influence of sintering time, sintering temperature, different amount of flux and different molar ratio of Fe / Sr to the magnetic properties of prepared SrFe12O19 magnetic particles, the optimum SrFe12O19 conditions were concluded. They are: sintering time: 3 hours; sintering temperature: 1073.15 k; flux NaCl amount: 15% wt of the reaction raw materials; Fe / Sr molar ratio: 11.4; the sample magnetic properties: Ms = 63.39emu / g; Mr = 33.44emu / g; Hc = 5798Oe, Mr / Ms = 1 : 1.90 ≈ 1:2. The prepared SrFe12O19 should be single crystal particles and in the shape of flake, and the particle size should be generally about 80-90nm with uniform distribution.

Coagulant Prepared by Gangue and its Application in Treatment of Coal Washing Wastewater

For solving the question about PFASS production using gangue, the best conditions for withdrawing the alkali and the silicon from the gangue during producing PFASS were obtained by using orthogonal experimental method. That is, the best acid soak conditions are: acid soak time(A) 1.5h, ratio of NaCl flux to gangue quality (B) 0.05:1, solid to liquid ratio(C) 1:10; the best alkaline leaching conditions are: alkaline leaching time 2h, concentration of the lye 5mol/L, solid to liquid ratio(C) is 1:10. PFASS, a high molecular inorganic coagulant, was prepared by gangue that is a kind of waste solid in mine. Processing conditions of the coagulant preparation were studied. The coagulant was used to treat a coal washing wastewater. The experimental results show that effluent quality is good. SS and turbidity of coal washing wastewater decrease evidently. And huge amounts of coal can be recycled.

Single crystal growth of the metallic triangular-lattice antiferromagnet PdCrO 2

We report details of single crystal growth of the metallic triangular-lattice antiferromagnet PdCrO 2 consisting of layers of Pd triangles and Cr triangles stacking along the c-axis. We used the NaCl flux method and obtained the crystals with the size as large as 2×3.5×0.3 mm 3. We confirmed that single crystals have the delafossite structure with the R 3 ¯ m symmetry. The electrical resistivity along the c-axis and that in the ab plane exhibit metallic temperature dependence with the anisotropic ratio ρ c / ρ ab of over 300 at low temperatures. The residual resistivity of as small as ρ 0 , ab = 45 n Ω cm and the residual resistivity ratio of over 100 indicate high quality of the crystals investigated. Nevertheless, there is no sign of superconductivity down to 0.3 K. These crystals are useful for the investigation of anisotropic magnetic and transport properties including the unconventional anomalous Hall effect (AHE).

Environmentally Friendly Growth of Well-Developed LiCoO2 Crystals for Lithium-Ion Rechargeable Batteries Using a NaCl Flux

High quality LiCoO2 crystals, useful as cathode material for lithium-ion rechargeable batteries, were successfully grown at a holding temperature of 800−1000 °C using the NaCl flux cooling method. The morphology, structure, size uniformity, and crystallinity of the obtained LiCoO2 crystals were obviously dependent on the growth conditions, such as the holding temperature and the starting composition. Well-developed, highly crystalline LiCoO2 crystals were first grown at a holding temperature of 900 °C from a NaCl flux. The grown LiCoO2 crystals had a hexagonal barrel-shaped structure with well-developed {001}, {104}, {101}, and {102} faces. On the basis of the powder X-ray diffraction data, the lattice parameters of the crystals were determined as a = 2.816 and c = 14.077 A. These values agree approximately with those from the literature (a = 2.816 and c = 14.052 A). The average crystal size was about 1.4 μm, which is a relatively small size when compared to previous reports. Transmission electron microsc...

ChemInform Abstract: A New Example of the Structure Type A2[{Z2R4}X9]: Synthesis and Crystal Structure of Na2[{(ON)Ce4}Cl9

AbstractSingle crystals of the new title compound are prepared by reaction of Ce, CeCl3, and NaN3 in a reactive NaCl flux (850 °C, 7 d).

Highly Crystalline, Idiomorphic Na2Ti6O13 Whiskers Grown from a NaCl Flux at a Relatively Low Temperature

AbstractWell‐developed, highly crystalline Na2Ti6O13 whiskers were successfully grown by cooling a NaCl flux at a relatively low temperature of 700 °C. The obtained Na2Ti6O13 whiskers were colorless and transparent. The whiskers grown at 700 °C were single phase and exhibit the lowest sizes of up to about 3.5 μm × 0.1 μm. From the results of SEM, XRD, and TEM, it was confirmed that the Na2Ti6O13 whiskers have very good crystallinity and elongated in the [lang]010[rang] directions. Furthermore, the whiskers exhibited good photocatalytic activity under ultraviolet light irradiation. It is reasonable to suppose that NaCl can be adequately used to synthesize high quality and well‐developed titanate whiskers in an environmentally friendly process of crystal growth.

A Unique Three-Dimensional Photocatalytic Structure Consisting of Highly Crystalline Na2Ti3O7 Whiskers Grown from a NaCl Flux

Highly crystalline and oriented Na2Ti3O7 whiskers were successfully and directly grown on a metallic titanium mesh using a NaCl flux cooling method for application to semiconducting photocatalysis. Specifically, unique three-dimensional photocatalytic materials were fabricated by converting a titanium mesh into a Na2Ti3O7 tubular mesh consisting of highly oriented whiskers. The formation mechanism of the oriented Na2Ti3O7 whiskers was investigated using field emission scanning electron microscopy, energy-dispersive X-ray spectrometry, and X-ray diffraction. From these results, the following conclusions could be confirmed. First, a titanium oxide layer was formed on the Ti wire surface by thermal oxidation. Since this oxide layer acts as a protective layer to thermal energy, the wire shape was maintained during Na2Ti3O7 whisker growth. Next, highly oriented Na2Ti3O7 whiskers were directly grown on the titanium oxide layer. During whisker growth, Ti was radially supplied from the bulk of the Ti mesh to the inner surface of the TiO2 layer. Finally, the Ti wire structure transitioned into a tubular structure consisting of Na2Ti3O7 whiskers. During the fabrication process, the Ti wire was dissolved by the NaCl flux, and the dissolved Ti ions reacted with O and Na ions to form TiO2 and Na2Ti3O7 layers. As a result, oriented and highly crystalline Na2Ti3O7 whiskers were directly grown on the TiO2 layer. The Ti wire was completely dissolved in this reaction system. Furthermore, the photocatalytic activities of the tubular mesh consisting of Na2Ti3O7 whiskers were confirmed by the photocatalytic degradation of a fluoroalkylsilane self-assembled monolayer and trichloroethylene under ultraviolet light irradiation. The whisker mesh developed herein exhibited good photocatalytic properties under ultraviolet light irradiation.

Microwave Absorption and Magnetic Studies of Strontium Hexaferrites Nanoparticles Synthesized by Modified Flux Method

M-type strontium hexaferrite nanocrystals of radar absorbing material (NRAM) i.e. SrFe12O19 were synthesized by modified flux method that combine the controlled chemical co-precipitation process for nucleation and complete uniform growth during annealing with NaCl flux. Uniform structural morphological transformation of nanocrystals from needle to hexagonal prism faces were noticed after annealing with increasing of heat treatment (HT) temperature from 800 to 1200°C for 4h. X-ray diffraction (XRD) results show the formation of various phases with increase in annealing temperature. The crystallinity and crystallite size are found to increase with increase in heat treatment temperature (15-40nm). The superparamagnetic behavior of strontium hexaferrite is confirmed by vibrating sample magnetometer (VSM) wherein it was noticed that magnetic field (10000 gauss max) did not have any effect on these materials. The transformation of magnetic properties i.e. from superparamagnetic to ferromagnetic behaviour after heating at various HT temperatures have been revealed by hysteresis loops under VSM study. The increase in saturation magnetization from 2.44 to 75.03 emu/gm is observed. Formation of ultrafine particles has been confirmed through field emission scanning electron microscope (FESEM). About 5 to10% of the needle like crystals in the ‘as synthesized’ condition were transformed to hexagonal pyramidal structure and most of the crystals are found to have plate like hexagonal structures with increase in heat treatment temperatures. The effect of such systematic morphological transformation of nanocrystals was observed in reflection loss properties in X band (8-12 GHz). The maximum reflection loss of -20.05, -24.31, -24.16, -25.22, -25.12, -24.01 dB at 8.1, 8.6, 9.2, 9.6, 10.7, and 12 GHz respectively are observed for the material heat treated at 1200°C. A significant increment from - 6.5 to -25.22 dB at 9.6 GHz in reflection loss (RL) is noticed due to symmetric morphological growth of RAM nanocrystal during annealing.

Changing the performance and morphology of polyethersulfone/polyimide blend nanofiltration membranes using trimethylamine

In this study, a few nanofiltration membranes were prepared by dissolving the blend of polyethersulfone/polyimide in dimethylformamide (DMF). Then, the prepared membranes were modified using new synthesized modifiers. We used methanol solution comprising 10 wt.% ethylenediamine (EDA) as a cross-linker to open imide group rings. PEG-triazine as a new modifier material, which was produced in the laboratory, was used in different concentrations (0.3 and 0.7 wt.%). Finally, trimethylamine (TMA) was added to complete the modification. This modification involves the formation of a covalence –C–N– bond between PEG-triazine and amine groups (according to addition-elimination reactions) at different temperatures. SEM, AFM, FTIR-ATR and contact angle measurements were used for membrane characterization. Rejection capability and flux of the obtained membranes were investigated by NaCl solution as feed using nanofiltration set-up. The hydrophilicity of PES/PI membranes was changed by modification. By adding the EDA and PEG-triazine, a decrease in NaCl flux (to 75 kg/m 2 h) and an increase in NaCl rejection (to 20%) were observed. By introducing TMA into the membrane recipe, the membrane flux increased from 75 until about 100 kg/m 2 h. The flux measurement of PEG 600 solution demonstrates that TMA-modified membrane has lower flux decline during the filtration process.

Sulfonated poly(arylene ether sulfone) thin-film composite reverse osmosis membrane containing SiO2 nano-particles

Novel thin-film nano-composite membranes containing SiO2 nano-particles are successfully fabricated via interfacial polymerization with trimesoyl chloride (TMC), sulfonated poly(arylene ether sulfone) copolymers and silica (SiO2) nano-particles on a polysulfone (PS) support membrane. Sulfonated poly(arylene ether sulfone) copolymers containing carboxylic and amino groups (cPES) are successfully prepared via direct polymerization as novel thin-film composite (TFC) reverse osmosis (RO) membrane material. Mesoporous SiO2 nano-particles are also successfully synthesized. The synthesized cPES copolymers, SiO2 nano-particles and fabricated cPES membranes are characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The incorporation of SiO2 nanoparticles were confirmed by energy dispersive X-ray spectroscopy (EDX). Moreover, the effects of different fabrication conditions on performance are investigated. The cPES membrane with 1% (w/w) SiO2, which is cured at 70°C, exhibited the high salt rejection value (96.8%) with respect to NaCl and good water flux value (32 L/m2h).

NaCl flux between apical and basolateral side recruits claudin-1 to tight junction strands and regulates paracellular transport

In multicellular organisms, epithelia separate and divide the internal environment maintaining appropriate conditions in each compartment. To maintain homeostasis in these compartments, claudins, major cell adhesion molecules in tight junctions (TJs), regulate movements of several substances through the paracellular pathway (barrier function). In this study, we investigated effects of the flux of several substances between apical and basolateral side on paracellular transport and TJ protein localization. NaCl flux from apical to basolateral side increased paracellular conductance (Gp) and recruited claudin-1 from lateral cell membrane to the apical end with the colocalization with occludin, one of the TJ proteins concentrated at TJ strands. Oppositely-directed flux of sucrose against NaCl flux inhibited these reactions and same directional flux of sucrose with NaCl enhanced the increase of Gp, whereas 10-kDa dextran inhibited these reactions regardless of the side of administration. Our present findings indicated that TJ protein localization and barrier function are regulated depending on the environmental differences between apical and basolateral side.

Growth of well-developed sodium tantalate crystals from a sodium chloride flux

Well-developed cubic crystals of NaTaO3 and NaTaO3 : La were successfully grown by cooling an NaCl flux at 650–1000 °C. Colourless and transparent NaTaO3 and NaTaO3 : La crystals were obtained from relatively low-temperature solutions containing 20 mol% solute, with a smallest average size of 0.18 μm. The crystal sizes and forms were highly dependent on the holding temperature, cooling rate, and starting composition. In particular, when La2O3 powders were added to the starting compositions, NaTaO3 : La crystals with a very unique surface morphology were grown from the NaCl flux. Additionally, the average size of the NaTaO3 : La crystals decreased dramatically when compared with that of the NaTaO3 crystals prepared under the same conditions. Furthermore, the NaTaO3 and NaTaO3 : La crystals exhibited high dye photodegradation activity. These results demonstrate that NaCl is adequate for synthesizing high quality and well-developed tantalate crystals.

Minimal Effects of VEGF and Anti-VEGF Drugs on the Permeability or Selectivity of RPE Tight Junctions

Bevacizumab and ranibizumab are currently used to treat age-related macular degeneration by neutralizing vascular endothelial growth factor (VEGF). In this study, the potential side effects on the outer blood-retinal barrier were examined. Human fetal RPE (hfRPE) cells were used because they are highly differentiated in culture. The claudin composition of RPE tight junctions was determined by RT-PCR, immunoblot analysis, and immunofluorescence. ELISA assays monitored the secretion and trafficking of VEGF and a fluid-phase marker, methylpolyethylene glycol (mPEG). Tight junction functions were assessed by the conductance of K(+) and Na(+) (derived from the transepithelial electrical resistance, TER) and the flux of NaCl and mPEG. Claudin-3, claudin-10, and claudin-19 were detected in RPE tight junctions. VEGF was secreted in equal amounts across the apical and basolateral membranes, but the apical membrane was more active in endocytosing and degrading VEGF. Exogenous VEGF and mPEG crossed the RPE monolayer by transcytosis, predominantly in the apical-to-basal direction. RPE tight junctions were selective for K(+), but did not discriminate between Na(+) and Cl(-). VEGF, bevacizumab, and ranibizumab had minimal effects on TER, permeation of mPEG, and selectivity for K(+), Na(+), and Cl(-). They had minimal effects on the expression and distribution of the claudins. RPE has mechanisms for maintaining low concentrations of VEGF in the subretinal space that include endocytosis and degradation and fluid-phase transcytosis in the apical-to-basal direction. RPE tight junctions are selective for K(+) over Na(+) and Cl(-). Permeability and selectivity of the junctions are not affected by VEGF, bevacizumab, or ranibizumab.

High-pressure crystal growth and magnetic and electrical properties of the quasi-one dimensional osmium oxide Na 2OsO 4

Na 2OsO 4 crystals were grown by a NaCl flux method under high pressure. It crystallizes in the Ca 2IrO 4-type structure without having additional elements or metal vacancies, which are usually accommodated. It appears that Na 2OsO 4 is a metal-stoichiometric Ca 2IrO 4-type compound never been synthesized to date. Na 2OsO 4 has the octahedral environment of Os 6+O 6 so that the electronic configuration is 5 d 2, suggesting the magnetic S=1 ground state. However, magnetization, electrical resistivity, and specific heat measurements indicated that the non-magnetic S=0 state is much likely for Na 2OsO 4 than the S=1 state. Band structure calculations and the structure analysis found that the disagreement is probably due to the statically uniaxial compression of the OsO 6 octahedra, resulting in splitting of the t 2 g band.

Spectral and kinetic characterization of CaS:Pr3+ phosphor synthesized through chemical co-precipitation route and post annealing process

Synthesis of Pr3+ doped CaS phosphor has been reported through chemical co-precipitation route and post annealing in the presence of NaCl, KCl and NH4Cl flux. Good crystallinity and cubic CaS phase is achieved after post-precipitation calcinations of powder at 900 °C for 1 h duration. Pseudo-spherical morphostructural features of micron-size particles are observed for phosphor prepared via chemical route. Phosphor samples are also prepared via solid-state carbothermal reduction technique for comparative studies and exhibit dendrite like structures. Prominent excitation bands at 276, 320 nm are observed for the present phosphor samples. The emission spectra show a duo-band feature at 495 and 580 nm where a spectral overlap of host lattice emission due to intrinsic defects and characteristic spectral features of Pr ion due to 3P0–1H4, 3P1–1H5, 1D2–3H4 and 3P0–3F2 transitions can be observed. The carbothermal route synthesized CaS:Pr shows spectral features of Pr ion due to 3P0–1H4 and 3P0–3Fj transitions. Electron spin resonance investigations reveal the presence of unintentional Mn2+ through a sextet signature. F+ electron trapping center is detected having g = 2.0034. Thermoluminescence glow curves possess a broad duo-band feature between room temperature −100 °C and >125 °C under host UV irradiation. Kinetic characterization using glow curve deconvolution reveals quasicontinuous distribution of traps having energy between 0.56 and 1.15 eV and frequency factors between 107 and 1011/sec.

Synthesis and optical properties of high-purity CoO nanowires prepared by an environmentally friendly molten salt route

CoO nanowires with diameters of 50 _80 nm, and lengths of up to more than 5 μm have been successfully synthesized by a simple environmentally friendly molten salt route, in which the precursor CoCO 3 nanoparticles are decomposed to form high-purity CoO nanowires in NaCl flux. The structure features and morphology of the as-prepared CoO nanowires were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED). The chemical composition and oxidation state of the prepared nanowires were systemically studied by X-ray photoelectron spectra (XPS) and laser Raman spectroscopy. The results indicated that the as-prepared CoO nanowires were composed of pure cubic CoO phase. The growth mechanism of the synthesized nanowires was also discussed in detail based on the experimental results.

Molten Salt Synthesis, Characterization, and Luminescence Properties of Gd2MO6:Eu3+ (M=W, Mo) Phosphors

Large‐scale micro‐ and nano‐sized Eu3+‐doped gadolinium tungstate and molybdate Gd2MO6:Eu3+ (M=Mo, W) red phosphors with special morphologies have been successfully prepared via an efficient molten salt synthesis (MSS) method at 950°C for 6 h using NaCl and as the reaction medium. The results of X‐ray powder diffraction patterns indicate that Gd2MoO6 and Gd2WO6 have monoclinic structures. The scanning electronic microscope and transmission electron microscope studies revealed that the samples of Gd2WO6:Eu3+ and Gd2MoO6:Eu3+ phosphors obtained by the MSS method in NaCl medium have a sphere‐like morphology, and the corresponding samples obtained in KCl medium have rod‐like morphologies. For the Gd2MoO6:Eu3+ phosphor obtained in NaCl and KCl media, the sphere‐like particles had an average grain size of ∼100 nm, and the size of the rod‐like particles ranged from 200 to 400 nm in length, and ∼150 nm in width, respectively. Compared with the same products obtained by the solid‐state reaction we had reported, the luminescent properties of Gd2MO6:Eu3+ (M=Mo, W) are largely dependent on their morphology and crystal size prepared using different fluxes of NaCl and KCl. The reaction time and temperature also play an important role in the crystallization of the samples.

A Comparative Study on Process-Properties Correlation of Nano Radar Absorbing Heat Treated Materials

Single phase M-type barium hexaferrite nano radar absorbing material (NRAM) i.e., BaFe12O19 were synthesized by modified flux method that combines the controlled chemical co-precipitation process for nucleation and complete uniform growth during annealing with NaCl flux under microwave annealing (MWA) and vacuum annealing (VA). Uniform morphological transformation of nano crystals from spherical (~ 10 nm) to prism faces (~ 35 nm) were observed under TEM during annealing. The effect of such systematic nano morphological transformation of NRAM was observed on magnetic and reflection loss (RL) properties. Maximum reflection loss (RL) was improved to 37.15 dB at 16.00 GHz for MWA at 760 watt and 27.56 dB at 15.75 GHz for VA at 1200 oC with continuous increasing absorption range under −10 dB for 2 mm thick coating layer in the Ku Band (12.4-18.0 GHz).. Excellent microwave absorption properties are a consequence of accurate EM match in the nano morphological planes, a strong natural resonance, as well as multipolarization. This process of crystal growth, morphology evolution and RL enhancement with respect to the heat treatments were also explained in terms of Ostwald ripening and quantum size effect.