Rare Metals

A detailed investigation on Pb-Ca-Sn alloys was made in order to choose suitable grid alloys materials for thin plate lead-acid batteries. The electrochemical performances of alloys were investigated by electrochemical corrosion experiment, scanning electron microscope (SEM) , and cyclic voltammetly (CV) test. The results indicate that Pb-Ca-Sn-Bi-Cu alloys can be used to make the grids used for thin grid leadacid batteries, the content of bismuth has primary effects on the corrosion resistance of grid alloys, the composition of alloys plays an important role on batteries performance, and appropriate scale of elements can be choosed to obtain optimal electrochemical performance. The lead-acid batteries using this kind of grid show good performance by cycle life test.

În societatea contemporană, economiile moderne sunt dependente, nu doar de resursele energetice, ci i de pământurile rare, considerate drept vitale pentru procesul dezvoltării economico-sociale, ș respectiv elementele "cheie" în vederea îndeplinirii diverselor obiective strategice 6 . Geopolitica

A rheo-diecasting process (RDC) was investigated for semisolid processing of an AZ91D magnesium alloy. The results of the RDC samples in as-cast state indicate that the microstructure of primary α-Mg particles has a fine size, nearly spherical morphology, and uniform distribution throughout the components. Due to the advanced microstructure and reduced level of defects, the RDC AZ91D Mg alloy exhibits an apparent improvement in mechanical properties. The quantitative metallographic investigations reveal that increasing the intensity of forced convection during the slurry preparation results in a promoted nucleation and reduced volume fraction of the primary phase solidified in the slurry maker.

nc-TiC/a-C:H nanocomposite films were prepared by filtered cathodic arc technique. The influence of C 2 H 2 /Ar flow ratio on the composition, structure, and mechanical properties of films was investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, nanoindentation, and ball-on-disc tribometry. The films show a nanocomposite structure in which TiC crystallites are embedded in the amorphous matrix of a-C:H phase. C content in films increases with the flow ratio of C 2 H 2 /Ar, simultaneously, the crystallite size of TiC decreases. Contrary to the nc-TiC/a-C:H films deposited by magnetron sputtering in which the sp3 C content increases with C 2 H 2 flow rate, the increase of C 2 H 2 flow rate leads to the increase of sp2 C content in films deposited by filtered cathodic arc technique. The nc-TiC/a-C:H films deposited by cathodic arc technique have a pronounced hardness maximum of 30 GPa under the C 2 H 2 /Ar flow ratio of 12. Tribological performance of films is controlled by the sp2 content in films. Higher sp2 content promotes the formation of graphite-like transfer layer during sliding, and results in lower wear rate and friction coefficient.

Leaching from silver sulfide using a copper-thiosulfate solution in the absence of ammonia was investigated. It is found that silver sulfide could be effectively dissolved in the copper-thiosulfate system without ammonia. The effects of thiosulfate concentration, copper-to-thiosulfate ratio, agitation vigorousness, pH values, and dissolved gases on the leaching of silver sulfide with the copper-thiosulfate solution were studied. A maximum extraction of 95.1% was achieved with the 0.12 mol/L thiosulfate and the 0.048 mol/L copper sulfate. It is shown that copper-to-thiosulfate ratio is an important factor in silver sulfide dissolution and oxygen is not needed to leach silver sulfide, which leads to the instability of the leaching system at high copper-to-thiosulfate ratio. On the other hand, the silver extraction is not affected by the pulp pH values.

Two compounds, Dy 2 (WO 4 ) 3 and GdY(WO 4 ) 3 , were synthesized by using the standard solid state reaction technique. The crystal structure was determined by powder X-ray diffraction and Rietveld refinement method. It is found that both compounds have Eu 2 (WO 4 ) 3 -type monoclinic structure, with space group C 2/c, Z = 4. The unit cell parameters of Dy 2 (WO 4 ) 3 are a = 0.75981(1) nm, b = 1.13220(1) nm, c = 1.13254(1) nm, and β = 109.8001(3)º, and those of GdY(WO 4 ) 3 are a = 0.76175(1) nm, b = 1.13543(1) nm, c = 1.13496(2) nm, and β = 109.8015(13)º. Each W atom has four oxygen nearest neighbors, while each rare-earth atom is surrounded by eight oxygen atoms. WO 4 tetrahedra share their four vertices with REO 8 (RE = Dy, Gd, or Y) trigondodecahedra and some REO 8 trigondodecahedra share an edge with each other. The phase transition and the magnetic properties were investigated by differential thermal analysis (DTA) and dc superconducting quantum interference device (SQUID) magnetometer.

Ti/AlTiN/Ti-diamondlike carbon (DLC) composite coatings were deposited by midfrequency magnetron sputtering and Hall ion source-assisted deposition on high-speed steel W 18 Cr 4 V substrates. The coating microstructure and mechanical properties, including hardness, elastic modulus, coefficient of friction, and wear properties were investigated by scanning electron microscopy, Raman spectroscopy, scratch and ball-ondisk friction tests, respectively. Fairly smooth composite coating with strong interfacial adhesion and good mechanical properties was produced. The substrate bias increases sp 3 bonds contents in the DLC layer, thus coating hardness increased from 14 to 24 GPa and elastic modulus from 190 to 230 GPa with the increased substrate bias. Adhesion of interfaces between Ti-DLC and AlTiN layer, AlTiN and the steel substrate decreased with the substrate bias. The coefficient of friction is between 0.10 and 0.15, except when the substrate bias is 500 V, it is 0.2. Composite coating wear resistance increased with the substrate bias.

Methylene blue dye (MB) was degraded photocatalytically in aqueous solution using Ag+ doped TiO2 under UV irradiation. The degradations of the dye using untreated TiO2 and Ag+ doped TiO2 were compared. Ag+ doped TiO2 was found to be more efficient. Using Ag+ doped TiO2 the filtration process was eliminated, as the particles became more settleable. The effect of various parameters such as catalyst loading, initial dye concentration, depth of solution, degree of adsorption, pH and O2 on dye degradation was studied. The extent of mineralization was studied by observing the COD removal at different time intervals. The effects of various interfering ions such as Cl−, NO3 −, CO3 2−, SO4 2−, Ca2+ and Fe3+ and electron acceptors such as H2O2, KBrO3 and (NH4)2S2O8 on the dye degradation was also studied. The degradation kinetics fitted well to Langmuir-Hinshelwood pseudo first order rate law. An aqueous solution of MB (20ppm) degraded by more than 99% after UV irradiation for 180 min with Ag+ doped TiO2 (2 g/L) and by more than 95% with untreated TiO2 (2 g/L). The COD removal was more than 91% with Ag+doped TiO2 and more than 86% with untreated TiO2 after 240 min. The degradation and COD removal of 5 times diluted textile wastewater was more than 98% and 79% respectively with 1 g/L Ag+ doped TiO2 after UV irradiation for 420 min.

The microstructure of Fe 30 Ni 20 Mn 20 Al 30 in both the as-cast condition and after annealing at 823 K for various times up to 72 h was characterized using transmission electron microscopy, scanning transmission electron microscopy, synchrotron-based X-ray diffraction, and atom probe tomography. The microstructure exhibited a basketweave morphology of (Mn, Fe)-rich B2-ordered (ordered b.c.c.) and (Ni, Al)-rich L2 1 -ordered (Heusler type) phases with a lattice misfit of only 0.85 % and interfaces aligned along h100i. The phase width increased from 5 nm for the as-cast alloy to 25 nm for 72 h annealed material, with no change in the elemental partitioning between the phases, with a time exponent for the coarsening kinetics of 0.19. Surprisingly, it was found that the room temperature hardness was largely independent of the phase width.

The Early Jurassic (ca. 177 Ma) Bokan Mountain granitic complex, located on southern Prince of Wales Island,
southernmost Alaska, cross-cuts Paleozoic igneous and metasedimentary rocks of the Alexander terrane of the
North American Cordillera and was emplaced during a rifting event. The complex is a circular body (~3 km in diameter)
of peralkaline granitic composition that has a core of arfvedsonite granite surrounded by aegirine granite.
All the rock-forming minerals typically record a two-stage growth history and aegirine and arfvedsonitewere
the last major phases to crystallize from the magma. The Bokan granites and related dikes have SiO2 from 72 to
78 wt.%, high iron (FeO (tot) ~3–4.5 wt.%) and alkali (8–10 wt.%) concentrations with high FeO(tot)/(FeO(tot) +
MgO) ratios (typically > 0.95) and the molar Al2O3/(Na2O + K2O) ratio < 1. The granitic rocks are characterized
by elevated contents of rare earth elements (REE), Th, U and high field strength elements (HFSE) and low contents of Ca, Sr, Ba and Eu, typical of peralkaline granites. The granites have high positive εNd values which are indicative of a mantle signature. The parent magma is inferred to be derived from an earlier metasomatized lithospheric mantle by low degrees of partial melting and generated the Bokan granitic melt through extensive fractional crystallization. The Bokan complex hosts significant rare-metal (REE, Y, U, Th, Nb) mineralization
that is related to the late-stage crystallization history of the complexwhich involved the overlap of emplacement
of felsic dikes, including pegmatite bodies, and generation of orthomagmatic fluids. The abundances of REE, HFSE,
U and Th as well as Pb and Nd isotopic values of the pluton and dikes were modified by orthomagmatic hydrothermal fluids highly enriched in the strongly incompatible trace elements, which also escaped along zones of structural weakness to generate rare-metal mineralization. The latter was deposited in two stages: the first relates to the latest stage of magma emplacement and is associated with felsic dikes that intruded
along the faults and shear deformations, whereas the second stage involved ingress of hydrothermal fluids that both remobilized and enriched the initial magmatic mineralization. Mineralization is mostly composed of “new” minerals. Fluorine complexing played a role during the transportation of REE and HFSE in hydrothermal fluids and oxygen isotopes in the granites and quartz veins negate the significant incursion of an external fluid and support a dominantly orthomagmatic hydrothermal system. Many other REE–HFSE deposits hosted by peralkaline felsic rocks (nepheline syenites, peralkaline granites and peralkaline trachytes) were formed by a similar two stage process.

The Early Jurassic (ca. 177 Ma) Bokan Mountain granitic complex, located on southern Prince of Wales Island, southernmost Alaska, cross-cuts Paleozoic igneous and metasedimentary rocks of the Alexander terrane of the North American Cordillera and was emplaced during a rifting event. The complex is a circular body (~3 km in diameter) of peralkaline granitic composition that has a core of arfvedsonite granite surrounded by aegirine granite. All the rock-forming minerals typically record a two-stage growth history and aegirine and arfvedsonite were the last major phases to crystallize from the magma. The Bokan granites and related dikes have SiO 2 from 72 to 78 wt.%, high iron (FeO (tot)~3 -4.5 wt.%) and alkali (8-10 wt.%) concentrations with high FeO (tot) /(FeO (tot) + MgO) ratios (typically N 0.95) and the molar Al 2 O 3 /(Na 2 O + K 2 O) ratio b 1. The granitic rocks are characterized by elevated contents of rare earth elements (REE), Th, U and high field strength elements (HFSE) and low contents of Ca, Sr, Ba and Eu, typical of peralkaline granites. The granites have high positive ε Nd values which are indicative of a mantle signature. The parent magma is inferred to be derived from an earlier metasomatized lithospheric mantle by low degrees of partial melting and generated the Bokan granitic melt through extensive fractional crystallization. The Bokan complex hosts significant rare-metal (REE, Y, U, Th, Nb) mineralization that is related to the late-stage crystallization history of the complex which involved the overlap of emplacement of felsic dikes, including pegmatite bodies, and generation of orthomagmatic fluids. The abundances of REE, HFSE, U and Th as well as Pb and Nd isotopic values of the pluton and dikes were modified by orthomagmatic hydrothermal fluids highly enriched in the strongly incompatible trace elements, which also escaped along zones of structural weakness to generate rare-metal mineralization. The latter was deposited in two stages: the first relates to the latest stage of magma emplacement and is associated with felsic dikes that intruded along the faults and shear deformations, whereas the second stage involved ingress of hydrothermal fluids that both remobilized and enriched the initial magmatic mineralization. Mineralization is mostly composed of "new" minerals. Fluorine complexing played a role during the transportation of REE and HFSE in hydrothermal fluids and oxygen isotopes in the granites and quartz veins negate the significant incursion of an external fluid and support a dominantly orthomagmatic hydrothermal system. Many other REE-HFSE deposits hosted by peralkaline felsic rocks (nepheline syenites, peralkaline granites and peralkaline trachytes) were formed by a similar two stage process.

The lack of experimental data and / or limited experimental information concerning both surface and transport properties of liquid alloys often require the prediction of these quantities. An attempt has been made to link the thermophysical properties of a ternary Cu-Sn-Ti system and its binary Cu-Sn, Cu-Ti and Sn-Ti subsystems with the bulk through the study of the concentration dependence of various thermodynamic, structural, surface and dynamic properties in the frame of the statistical mechanical theory in conjunction with the quasi-lattice theory (QLT). This formalism provides valuable qualitative insight into mixing processes that occur in molten alloys.

Intermacromolecular complexation between chitosan and sodium caseinate in aqueous solutions was studied as a function of pH (3-6.5), using absorbance measurements (at 600 nm), dynamic light scattering (DLS), and transmission electron microscopy (TEM). The chitosan-caseinate complexes formed were stable and soluble in the pH range 4.8-6.0. In this pH range, the biopolymers had opposite charges. At higher concentrations of chitosan (0.15 wt%), the soluble complexes associated to form larger particles. DLS data showed that, between pH 4.8 and 6.0, the particles formed by the complexation of chitosan and caseinate had sizes between 250 and 350 nm and these nanoparticles were visualized using negative staining TEM. Above pH 6.0, the nanoparticles associated to form larger particles, causing phase separation. Addition of NaCl increased the particle size. The pH dependence of the zeta potential of the mixture solutions was appreciably different from that of the pure protein and pure chitosan solutions.

The effects of the modification of electrode/ceramic interfaces through a chemical solution deposition-derived PbO buffer layer on the fatigue endurance of lead zirconate titanate (PZT) thin films were investigated. The grain size and the surface roughness of the PZT films increased through PbO interfacial modification. Moreover, the PZT films with PbO interfacial modification had a better crystallographic structure and no evident secondary phases were observed. While the remanent polarization and dielectric constant were reduced, the fatigue endurance was improved. Based on the results, the mechanism for the fatigue endurance improvement was discussed.

Photocatalytic degradation reactions of methylene blue on nanocrystalline TiO2 (nc-TiO2) films were studied in situ by surface mass spectrometric techniques including secondary ion mass spectrometry, laser desorption direct ion mass spectrometry, and laser desorption/laser photoion mass spectrometry. The parent ion of methylene blue and/or its reduced form leucomethylene blue was observed with little fragmentation by all methods prior to ultraviolet

In order to improve the cycling stability of AB 5 type alloy electrodes, rapid quenching technology and new alloy composition design were employed. A hydrogen storage alloy with nominal composition La 0.6 Ce 0.4 Ni 3.6 Co 0.65 Mn 0.4 Al 0.2 Ti 0.05 (FeB) 0.1 was prepared by vacuum magnetic levitation melting under high purity argon atmosphere, followed by rapid quenching at different cooling rates. XRD results show that all alloys exhibit the single-phase CaCu 5-type structure. Electrochemical tests indicate that rapid quenching can slightly improve the cycling life of the alloy. Nevertheless, the high-rate dischargeability of the quenched alloys is lower than that of the as-cast alloy.

Polycrystalline La1-xNaxFeO3 (0.0≤x≤0.3) solid solutions were synthesized by a solution combustion method using glycine as a fuel. The combustion synthesized compounds were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), diffused reflectance (DR) in the UV-vis, and magnetic measurements. The crystal structure examined by X-ray powder diffraction indicated that the samples were single phase and crystallized in an orthorhombic (space group, Pbnm no.62) structure. The parent and sodium-substituted compounds showed canted anti-ferromagnetic behavior associated with an increase in magnetic moment as Na content increased. The changes in magnetic properties of the materials were correlated to the changes in structural features, as shown by Rietveld structural refinement of the materials.

Anode material Li 4 Ti 5 O 12 was prepared at 800 C by a solid-state reaction, followed by heat-treatment at 600 C for different times (0, 2, 8, and 12 h). The effects of heat-treatment time on the particle morphology, rate-capability, and electrode kinetic process of the Li 4 Ti 5 O 12 electrode, and on the lithium ion diffusion coefficient inside the Li 4 Ti 5 O 12 electrode were investigated. Proper heat treatment could smoothen the particle surface of Li 4 Ti 5 O 12 particles and increase the rate-capability of the electrode. Overlong heat treatment might cause particle aggregation and hence result in a poor electrode kinetic process. A sample with 8 h of heat treatment showed the best rate-capability and the lowest electrode reaction resistance. Heat treatment for 2-8 h does not significantly change the lithium ion diffusion coefficient inside the Li 4 Ti 5 O 12 electrode, whereas, 12-h treatment results in a lower lithium ion diffusion coefficient.

The Gerakario Cu-Au porphyry deposit in the Kilkis ore district, northern Greece, contains epithermal quartz-stibnite veins on the eastern side of the deposit, which crosscut a two-mica gneiss. Metallic mineralization in these veins consists of stibnite + berthierite + native antimony + pyrite + arsenopyrite, and minor marcasite, pyrrhotite, chalcopyrite, löllingite, and native gold. Bulk geochemical analyses of the ore reveal an enrichment in critical and rare metals, including Ag, Au, Bi, Ce, Co, Ga, La, and Sb. Analysis of stibnite with LA-ICP-MS showed an enrichment in base metals (As, Cu, Pb), as well as weak to moderate contents of critical and rare metals (Ag, Bi, Ce, La, Re, Sm, Th, Ti, Tl). A statistical analysis of the trace elements show a positive correlation for the elemental pairs Ce-La, Ce-Sb, and La-Sb, and a negative correlation for the pair Bi-Sb. Fluid inclusions in the A-type veins of the porphyry-style mineralization show the presence of fluid boiling, resulting in a highly saline aqueous fluid phase (35.7 to 45.6 wt.% NaCl equiv.) and a moderately saline gas phase (14 to 22 wt.% NaCl equiv.) in the system H2O-NaCl-KCl at temperatures varying between 380o and 460 oC and pressures from 100 to 580 bar. Mixing of the moderate saline fluid with meteoric water produced less saline fluids (8 to 10 wt.% NaCl equiv.), which are associated with the epithermal quartz-stibnite vein mineralization. This process took place under hydrostatic pressures ranging from 65 to 116 bar at a depth between 600 and 1000 m, and at temperatures mainly from 280o to 320 oC.

The powder space holder (PSH) and powder injection molding (PIM) methods have an industrial competitive advantage because they are capable of the net-shape production of micro-sized porous parts. In this study, micro-porous Ti6Al4V alloy (Ti64) parts were produced by the PSH-PIM process. Ti64 alloy powder and spherical polymethylmethacrylate (PMMA) particles were used as a space holder material. After molding, binder debinding was performed by thermal method under inert gas. Debinded samples were sintered at 1250ºC for 60 min in a vacuum (10 −4 Pa). Metallographic studies were conducted to determine densification and the corresponding microstructural changes. The surface of sintered samples was examined by SEM. The compressive stress and elastic modulus of the micro-porous Ti64 samples were determined. The effects of fraction of PMMA on the properties of sintered micro-porous Ti64 alloy samples were investigated. It was shown that the fraction of PMMA could be controlled to affect the properties of the Ti alloy.

TiN/Si3N4 nanocomposites were fabricated from β-Si3N4 and TiN nano powders by powder processing routes. The specimens were consolidated at 1600 °C for 3 min by spark plasma sintering, and nearly full densification was obtained in the resulting sintered bulk composites. The TiN phase grows rapidly and a typical twin structure of TiN can be observed in the composites. The grain size and distribution for TiN may affect the electrical resistivity, leading to a pulse current through the sintering compact. The resulting microstructure for the composite containing 10 wt% TiN reveals that grain coarsening behavior for β-Si3N4 based grains is accelerated, and the composite has the highest toughness of 4.9 MPa m1/2 among all these composites. The other composites show nanosized β-Si3N4 based grains with a fracture toughness of nearly 4.2 MPa m1/2.▶ By utilizing spark plasma sintering technique, the microstructural development of Si3N4 based nanocomposites with varying amount of nano TiN addition was demonstrated, and the relationship between microstructure and performance, such as mechanical properties and electrical conductivity, of these TiN/Si3N4 based composites was discussed. ▶ These results enable us to understand the effects of a pulse direct current during sintering and make it possible to control the resulting microstructure and properties of Si3N4 based nanocomposites in spark plasma sintering.

The dissolution of silver with thiosulfate and copper ions was studied in a batch-stirred reactor at 25°C in the absence and presence of various ammonium ions and oxygen concentrations in the aqueous solution. Leaching silver with 4 mgÁL -1 oxygen in the aqueous solution requires high concentration of ammonium and thiosulfate ions. High silver dissolution is achieved at pH of high cupric tetraamine concentration, around pH 9.8, but a high degradation of thiosulfate ions is resulted from their oxidation by the presence of oxygen. When the oxygen concentration is below 1 mgÁL -1 , dissolved silver thiosulfate species are fairly stable and the degradation of thiosulfate ions in the aqueous solution is low. Under these conditions, high silver dissolution is attained using low thiosulfate concentration. At the oxygen concentration of 4 mgÁL -1 , dissolved silver thiosulfate species precipitate out of the aqueous solution significantly affecting silver dissolution. Precipitation of dissolved silver thiosulfate species occurs because of oxidation of the thiosulfate bonding to the silver.

This study aimed to find an efficient way to recover Sb from the SbCl 5 acid solution obtained by the chloride leaching process of the tin-depleted residue. Sb was recovered in the form of hydrated antimony pentoxide through the hydrolysis process. The effects of hydrolysis ratio and aging time on the Sb recovery process were studied, and the corresponding trends were established. The experimental results show that the amount of the antimony free ions increases with the hydrolysis ratio and aging time. This decreases the concentration quotient of the hydrolysis reaction and thus facilitates the reaction. Product crystallinity is affected by the solution supersaturation, which varies at different stages with aging time. As a result, the optimal conditions of recovering Sb correspond to the hydrolysis ratio of 1.5 and aging time of 7 days with the recovery rate of 97 %.

The dispersion of multiwalled carbon nanotubes (CNTs) in an ethylene propylene rubber matrix was investigated using an internal mixer. Poly(ethylene-co-polyvinyl acetate) (EVA) statistic copolymer was used as a dispersing agent. The effects of the concentration of the dispersing agent and the matrix viscosity on the quality of the dispersion of 1 wt % of CNTs were studied by using microscopy and rheology in the melt state. It was demonstrated that the dispersion is governed principally by the viscosity of the matrix. As expected, better dispersion was observed when the matrix exhibited a lower viscosity.

Multiwalled carbon nanotubes (CNTs) were coated by a molybdenum layer using carbonyl thermal decomposition process with a precursor of molybdenum hexacarbonyl. The Mo-coated CNTs (Mo-CNTs) were added into copper powders to fabricate Mo-CNT/Cu composites by means of mechanical milling followed by spark plasma sintering. The Mo-CNTs were uniform dispersion in the Cu matrix when their contents were 2.5 vol.%-7.5 vol.%, while some Mo-CNT clusters were clearly observed at additions of 10.0 vol.%-15.0 vol.% Mo-CNTs in the mixture. The mechanical, electrical, and thermal properties of the Mo-CNT/Cu composites were characterized, and the results showed that the tensile strength and hardness were 2.0 and 2.2 times higher than those of CNT-free specimens, respectively. Moreover, the Mo-CNT/Cu composites exhibited an enhanced thermal conductivity but inferior electrical conductivity compared with sintered pure Cu. The uncoated CNT/Cu composites were fabricated by the similar processes, and the measured tensile strength, hardness, thermal conductivity, and electrical conductivity of the CNT/Cu composites were lower than those of the Mo-CNT/Cu composites.

This presentation was part of an invited conference  at the “ 2011 Invitational Seminar on Rare Metals ”, held in Seoul, Korea, October 5 , 2011, on behalf of KORES, and introduces the Brazilian general aspects on Geology and Mining , particularly for "rare metals" and rare earths possibilities.
As for the rare earths it presents the classification and location of known occurrences and deposits in Brazil and some adjacent South American countries.

The frst-principles calculation of the disordered Llo phase boundary for the Fe-Pd system is attempted by combining the FLAPW electronic structure total energy calculations and the cluster variation method via the cluster expansion method. The lattice vibration effects are taken into account based on the Debye-Gruneisen model within quasi-hannonic approximation. The transition temperature is reproduced with very high accuracy. However, the experimental congruent composition of disordered Llo phase that significantly deviates from 1:l stoichiometry is not reproduced. Further calculations are attempted based on the phenomenological Lennard-Jones type pair potential, which is capable of introducing both tetragonality of the Llo ordered phase and additional configurational freedom because of the magnetic spins. The preliminary calculations indicate that the tetragonality enhances the stability of the Llo ordered phase and the magnetic contributions also change the transition temperature. Despite these fmdings, the shift of the congruent composition still remains as a subject that needs further research. The electronic origin of the shifting of the congruent composition is briefly discussed.

Vanadium Redox Battery (VRB) is one of the promising electrical energy storage systems. The charge/discharge efficiency of VRB is affected by the permeability of vanadium ions, the water or acid uptake, and the ionic conductivity. In this study, a cellulose acetate/polypropylene (CA/PP) composite nano-porous membrane was prepared. The solvent/non-solvent method was used to form the CA membrane. It was supported on a PP fabric. The polyethylene glycol (PEG) was a pore-forming agent in the CA solution. This composite membrane had shown good ionic conductivity and low permeation to the vanadium ion as the commercial proton conducting membrane (Nafion). However, the membrane cost is expected to be one order of magnitude lower than the cost of Nafion.

Because of flexible design, long life, and low-cost maintenance, redox flow cell has been recognized as one of the reliable energy storage techniques in remote power systems. In redox flow cells, electrolyte circulation through carbon felt is necessary in order to produce effective ion exchange during the charge and discharge operations. Pumping power required for electrolyte circulation could be significant, especially for multi-stack cell, due to low permeability of the porous carbon felt. Moreover, effective method for transporting bubbles formed inside the electrode is necessary for increasing the effective area of reaction of the electrodes. To further improve the overall performance of the redox flow cells, we proposed several novel designs of electrolyte inlet/outlet port and flow passage in carbon felt intending to reduce the electrolyte pumping power and to increase the effective area. Based on our numerical modeling, it is found that pumping power can be reduced by appropriate inlet/outlet port design and carbon felt with flow channel. The non-uniform flow pattern may cause the bubbles to be carried away from the electrodes effectively. The proposed designs can be applied not only for the single-stack cell but also applicable for the multiple-stacked cells.

PtRu nanoparticles deposited on a carbon black substrate are catalysts commonly employed for the electrooxidation of methanol and carbon monoxide-containing hydrogen feeds [1,. However, improvement of effective electrocatalysts is an essential goal in the development of a practical DMFC. The use of carbon black as a support for noble metals is frequent in the electrodes of polymer membrane electrolyte fuel cells, but the impact of the chemical and physical properties of the carbon on electrocatalytic performance are not yet sufficiently understood. The presence of oxygen surface groups influences the surface behaviour of carbons to a considerable extent . As examples, the wettability and adsorptive behaviour of a carbon, as well as its catalytic and electrical properties, are influenced by the nature and extent of such surface groups. The varying role of oxygenated functionalities on the formation of the dispersed platinum has been established [5-8], but not with an additional metal such as ruthenium. In the present investigation we report how the performance in methanol electrooxidation of PtRu nanoparticles deposited on a carbon black substrate, previously functionalized with oxygen surface groups, is improved.

The microstructure and wear performance of Al2O3-13% TiO2 coatings prepared by plasma spraying of agglomerated nanoparticle powders were investigated. SEM analysis showed that the as-sprayed Al2O3-TiO2 coatings comprise of two kinds of typical region: fully melted region and unmelted/partially melted nanostructured region, which is different than the conventional coating with lamellar structure. It is shown that the microhardness of the nanostructured coatings was about 15%-30% higher than that of the conventional coating and the wear resistance is significantly improved, especially under a high wear load. The nanostructured coating sprayed at a lower power shows a lower wear resistance than the coatings produced at a higher power, because of the presence of pores and microstructural defects which are detrimental to the fracture toughness of the coatings.

In this study, neodymia doped poly(vinyl) alcohol/zirconium–cerium acetate (PVA/Zr-Ce) nanofibers were prepared using the electrospinning technique, and then calcined at 800°C for 2 hours. For this purpose, PVA/Zr-Ce polymer solutions doped with different concentrations of neodymia were prepared using electrospinning technique, and then calcined and sintered at 800°C for 2 hours. The effect of neodymia doping was investigated in terms of solution properties, morphological changes and thermal characteristics. The fibers were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and scanning electron microscope (SEM). The measurements showed that the conductivity, pH, viscosity, and surface tension of the hybrid polymer solutions have decreased with increasing Nd acetate content. The FT-IR spectra of the fibers were in good accordance with the literature. The average crystal size values for calcined and sintered samples which were obtained from precursor solutions were calculated. XRD analysis showed that the crystallite size was decreased with increasing Nd content. This result is verified by the calculation of the total areas of the peaks appeared in the XRD spectra. The very sharp and high intense peaks found in the diffraction patterns revealed the crystalline nature of the product. Moreover, the SEM micrograph of the fibers showed that the average fiber diameters decreased with increasing Nd content.