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Magnesium and its alloys are the most investigated materials for solid-state hydrogen storage in the form of metal hydrides, but there are still unresolved problems with the kinetics and thermodynamics of hydrogenation and dehydrogenation of this group of materials. Severe plastic deformation (SPD) methods, such as equal-channel angular pressing (ECAP), high-pressure torsion (HPT), intensive rolling and fast forging, have been widely used to enhance the activation, air resistance, and hydrogenation/dehydrogenation kinetics of Mg-based hydrogen storage materials by introducing ultrafine/nanoscale grains and crystal lattice defects. These severely deformed materials, particularly in the presence of alloying additives or second-phase nanoparticles, can show not only fast hydrogen absorption/desorption kinetics but also good cycling stability. It was shown that some materials that are apparently inert to hydrogen can absorb hydrogen after SPD processing. Moreover, the SPD methods were effectively used for hydrogen binding-energy engineering and synthesizing new magnesium alloys with low thermodynamic stability for reversible low/room-temperature hydrogen storage, such as nanoglasses, high-entropy alloys, and metastable phases including the high-pressure {\gamma}-MgH2 polymorph. This article reviews recent advances in the development of Mg-based hydrogen storage materials by SPD processing and discusses their potential in future applications.

RESUMEN El Alprazolam pertenece a las benzodiazepinas. Sus efectos se atribuyen a que actúa sobre receptores de membrana específicos, lo cual facilita la acción inhibitoria presináptica y postsináptica del ácido γ-aminobutírico (GABA), especialmente en la formación reticular ascendente. Se utiliza para el tratamiento de los estados de ansiedad, crisis de angustia, ataques de pánico y estrés intenso. Este estudio se realizó para analizar los parámetros comparativos de control de calidad in vitro mediante la evaluación de la variación de peso, friabilidad, dureza, tiempo de desintegración, perfil y eficiencia de disolución entre el medicamento innovador (Xanax®) y multifuentes que son comercializados en el mercado peruano. Para realizarlo, se seleccionaron tabletas de Alprazolam 0,5 mg multifuente de diferentes laboratorios comparándolos con el medicamento innovador y se evaluaron las características fisicoquímicas y biofarmacéuticas. Los ensayos farmacopeicos se evaluaron según lo establecido en la USP 42. Los resultados de las pruebas fisicoquímicas indicaron que las muestras analizadas no tenían diferencia significativa y estaban dentro de lo establecido en la farmacopea, así mismo el perfil y eficiencia de disolución permitieron establecer que el comportamiento biofarmacéutico de las mismas era muy similar para ambos tipos de molécula. Se estableció que las tabletas multifuentes de Alprazolam 0,5 mg de esta investigación son bioequivalentes con el innovador, por lo que permite proponer a la comunidad científica la determinación de la equivalencia biofarmacéutica como elemento de apoyo en la toma de decisiones de compra en el servicio farmacéutico. ABSTRACT Alprazolam belongs to benzodiazepines. Its effects are attributed to the fact that it acts on specific membrane receptors, which facilitates the presynaptic and postsynaptic inhibitory action of γ-aminobutyric acid (GABA), especially in the ascending reticular formation. It is used to treat anxiety states, panic attacks, and intense stress. This study was carried out to analyze comparative parameters of in vitro quality control by evaluating the variation in weight, friability, hardness, disintegration time, profile and dissolution efficiency between the innovative drug (Xanax®) and multi-sources tablets that are marketed in the Peruvian market. To perform this, Alprazolam 0.5 mg multi-source tablets were selected from different laboratories comparing them with the innovative medicine and the physicochemical and biopharmaceutical characteristics were evaluated. Pharmacopoeial trials were evaluated as established in USP 42. The results of physicochemical tests indicated that analyzed samples did not have a significant difference and were within the established in the pharmacopoeia, as well as the profile and dissolution efficiency allowed to establish that their biopharmaceutical behavior was very similar for both types of molecules. It was established that Alprazolam 0.5 mg multi-source tablets from this research are bioequivalent with innovator, which makes it possible to propose to scientific community determination of biopharmaceutical equivalency as a support element in decision-making process for purchasing services pharmacist.

The hydrogen storage properties of the novel equiatomic TiZrNbFeNi and non-equiatomic Ti20Zr20Nb5Fe40Ni15 high entropy alloys (HEAs) were studied. These alloys were designed with the aid of thermodynamic calculations using the CALPHAD method due to their tendency to form single C14 Laves phase, a phase desirable for room-temperature hydrogen storage. The alloys, which were synthesized by arc melting, showed a dominant presence of C14 Laves phases with the (Zr, Ti)1(Fe, Ni, Nb, Ti)2 constitution and small amounts of cubic phases (

Despite potential of hydride-forming alloys for hydrogen storage, there have been few alloys which can reversibly store hydrogen without heating or activation treatment. In this study, a high-entropy alloy is designed for room temperature hydrogen storage based on three criteria: total valence electron concentration (VEC) of 6.4, single-phase thermodynamic stability (examined by CALPHAD calculations) and AB2H3 hydride formation (A: hydride-forming elements, B: elements without affinity to hydrogen, H: hydrogen). The designated alloy, TiZrCrMnFeNi containing 95 wt% C14 Laves phase, absorbs and desorbs 1.7 wt% of hydrogen (hydrogen-to-metal ratio: 1) at room temperature with a fast kinetics and without activation treatment.

High-pressure torsion (HPT) is widely used not only as a severe plastic deformation (SPD) method to produce ultrafine-grained metals but also as a mechanical alloying technique to synthesize different alloys. In recent years, there have been several attempts to synthesize functional high-entropy alloys using the HPT method. In this paper, the application of HPT to synthesize high-entropy materials including metallic alloys, hydrides, oxides and oxynitrides for enhanced mechanical and hydrogen storage properties, photocatalytic hydrogen production and high light absorbance is reviewed.

Crystal structure and hydrogen storage properties of a novel equiatomic TiZrNbCrFe high-entropy alloy (HEA) were studied. The selected alloy, which had a A3B2-type configuration (A: elements forming hydride, B: elements with low chemical affinity with hydrogen) was designed to produce a hydride with a hydrogen-to-metal atomic ratio (H/M) higher than those for the AB2- and AB-type alloys. The phase stability of alloy was investigated through thermodynamic calculations by the CALPHAD method. The alloy after arc melting showed the dominant presence of a solid solution C14 Laves phase (98.4%) with a minor proportion of a disordered BCC phase (1.6%). Hydrogen storage properties investigated at different temperatures revealed that the alloy was able to reversibly absorb and fully desorb 1.9 wt% of hydrogen at 473 K. During the hydrogenation, the initial C14 and BCC crystal structures were fully converted into the C14 and FCC hydrides, respectively. The H/M value was 1.32 which is higher than the value of 1 reported for the AB2- and AB-type HEAs. The present results show that good hydrogen storage capacity and reversibility at moderate temperatures can be attained in HEAs with new configurations such as A3B2/A3B2H7.

Made available in DSpace on 2020-12-12T01:19:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01 Ministry of Education, Culture, Sports, Science and Technology Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Instituto Serrapilheira Despite significant studies on mechanical properties of high-entropy alloys (HEAs), there have been limited attempts to examine the biocompatibility of these alloys. In this study, a lattice-softened high-entropy alloy TiAlFeCoNi with ultrahigh hardness (examined by Vickers method), low elastic modulus (examined by nanoindentation) and superior activity for cell proliferation/viability/cytotoxicity (examined by MTT assay) was developed by employing imperial data and thermodynamic calculations. The designated alloy after casting was processed further by high-pressure torsion (HPT) to improve its hardness via the introduction of nanograins, dislocations and order-disorder transformation. The TiAlFeCoNi alloy with the L21-BCC crystal structure exhibited 170–580% higher hardness and 260–1020% better cellular metabolic activity compared to titanium and Ti-6Al-7Nb biomaterials, suggesting the high potential of HEAs for future biomedical applications. WPI International Institute for Carbon-Neutral Energy Research (WPI-I2CNER) Kyushu University School of Applied Sciences University of Campinas (UNICAMP) Institute of Biosciences São Paulo State University (UNESP) Institute of Biosciences São Paulo State University (UNESP) Ministry of Education, Culture, Sports, Science and Technology: 19H05176 FAPESP: 2013/23620-4 FAPESP: 2018/15968-4 Instituto Serrapilheira: Serra-1709-17362

In this study, a commercial Mg-based ZK60 alloy was modified with 2.5 wt% mischmetal (ZK60-2.5 wt%Mm) and further processed by cold rolling followed by manual filing. The chips obtained by manual filing process were collected from the as cast (AC) and the cold rolled (CR) materials. The hydrogen storage properties were evaluated by kinetics measurements at 350 °C. A full microstructural characterization including optical, scanning and transmission electron microscopy (MO, MEV and TEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) was performed in the samples. For the first absorption of both filed samples the H storage capacity showed a value around 6.0 wt% after 1 h while for the CR sample it was close to 1.25 wt% after the same time. The manual filing produced samples with higher hydrogenation kinetics compared with that of the CR sample. Besides, their hydrogen storage capacity was maintained close to the theoretical value (6.75 wt%). The breakage and pulverization of the intermetallic phases gave the chips from the CR alloy the faster hydrogenation kinetics, especially for H-desorption.

High-entropy alloys are potential candidates for various applications including hydrogen storage in the hydride form and energy storage in batteries. This study employs HEAs as new anode materials for nickel - metal hydride (Ni-MH) batteries. The TixZr2-xCrMnFeNi alloys with different Ti/Zr ratios, having the C14 Laves structure, are used. These alloys are selected because they show room-temperature hydriding/dehydriding capability. The HEAs successfully act as negative electrode of Ni-MH batteries with good charge/discharge cyclability, while there are optimum Ti/Zr ratios for the highest storage capacity and the fastest activity. These findings introduce HEAs as potential anode materials for Ni-MH battery application.

Mg-AB5 composites are promising systems for hydrogen storage applications, due to their possibility of hydrogen cycling at relatively low temperatures. Traditionally, these composites are mainly processed by high-energy ball milling (HEBM) techniques employing longer processing times. In this study, cold rolling was applied to prepare MgH2 LaNi5 composites and the hydrogen storage properties were investigated. The materials were processed using a vertical rolling mill under argon atmosphere, leading to a good homogeneity and no contamination at shorter processing times. The mixture of MgH2-1.50 mol.% LaNi5 showed the best hydrogen storage properties at 200 °C and 100 °C and the lowest desorption temperature even when compared to cold rolled MgH2. The results indicate that the composite MgH2 LaNi5 is transformed into a mixture of three phases MgH2, Mg2NiH4 and LaH3 upon hydrogen absorption/desorption cycles. The synergetic effect among these phases when in appropriate proportion in the sample seems to play a crucial role in the acceleration of hydrogen absorption/desorption kinetics at lower temperatures in comparison to MgH2.

This article aims to build possible relationships between psychoanalysis and some of the most puzzling works of René Magritte (1898 - 1967), keeping consistent with the curating of an exhibition called "Magritte: The Mystery of the Ordinary". Thus, we dedicated to reading materials of commentators and critics of the painter's work, we also investigated the texts produced by Magritte himself, in which the painter introduces some key-concepts for the understanding of his artistic thinking: aesthetic emotion, poetics, mysteries of the ordinary, uncanny (resounding the Freudian’s Umheimlich). Thereby, we were careful to not produce superficial and reductionist interpretations, which only implement psychoanalysis to the art. Therefore, we aimed to produce a critical interpretation, attentive to details of art works, demonstrating the implications present there and showing possible links between the work of Magritte and psychoanalytic theory.

Mechanical properties of high-entropy alloys (HEAs) have received significant attention, while there are still attempts to find new strategies to further improve their properties. In this study, to produce an ultrahard HEA, an FCC carbide was introduced in a BCC-based AlTiFeCoNi alloy by the assistance of CALPHAD thermodynamic calculations. The alloy was synthesized by arc melting and processed by severe plastic deformation via the high-pressure torsion (HPT) method to generate defects. The material showed nanograin formation, dislocation accumulation, carbide fragmentation, L21 → BCC ordered-to-disordered phase transformation, and accordingly an ultrahigh hardness of 950 Hv after HPT processing.

The aim of this work is to investigate the influence of some processes variables on the microstructure and hydrogen absorption kinetics of MgH2 - X wt.% TiFe composites. Samples were synthesized by high-energy ball milling in a planetary (X = 40, 50, 60) and shaker mill (X = 40) under high-purity argon atmosphere. Commercial MgH2 instead of Mg powder was used in order to reduce adherence on the vial and balls. TiFe powder was previously produced by ball milling a mixture of TiH2 and Fe powders followed by a reaction synthesis at 600oC. Milled composites samples were characterized by XRD and SEM analysis. Milling time was preliminary investigated (X = 40) in the planetary ball mill (6 to 36h). TiFe particle size reduction was shown to be difficult since they are surrounded by MgH2 matrix. Strong particle reduction was obtained by using a shaker mill only for 2 hours and adding cyclohexane as process control agent. No reaction between MgH2 and TiFe compound was observed in any milled sample. Hydrogen absorption kinetics measurements of the as-milled samples were conducted on an Sieverts' type apparatus at room temperature after hydrogen desorption at 350oC under vacuum. The best hydrogen kinetics (3 wt% at the first hour) was attained by the planetary milled sample (36 h). Higher hydrogen capacity was observed for the sample milled in the shaker mill (4.0 wt.%), but only after 13h.

Mixtures of XMg–Co containing different amounts of Mg (X = 2, 3 and 7) were reactive milled under hydrogen atmosphere. 2Mg–Co only formed the Mg 2 CoH 5 complex hydride, while the mixtures 3Mg–Co and 7Mg–Co formed different contents of Mg 2 CoH 5 and MgH 2 . Their structural features and hydrogen storage properties were analyzed by different techniques. In-situ synchrotron X-ray diffraction, combined with thermal analysis techniques, (differential scanning calorimetry, thermal gravimetric analysis and quadrupole mass spectrometer) was carried out to observe the behavior of the MgH 2 –Mg 2 CoH 5 mixtures during the first H-desorption. It was found that the presence of the Mg 2 CoH 5 complex hydride has a beneficial effect on the first H-desorption of the MgH 2 . Additionally, after first desorption, conventional hydrogenation under high pressure and high temperature of 3Mg–Co and 7Mg–Co samples led to the formation of the Mg 6 Co 2 H 11 complex hydride. The presence of Mg 6 Co 2 H 11 considerably impaired the desorption properties of the nanocomposites.

In this study, powder mixtures of MgH 2 + 2 mol.% X, with X = Nb, Nb 2 O 5 , NbF 5 , Fe, Fe 2 O 3 , FeF 3 , were processed by mechanical milling at liquid nitrogen temperature (cryomilling). The effect of additives on crystalline structure, thermal properties and hydrogen storage properties of the mixtures were investigated. Morphological investigations indicated a heterogeneous particle size distribution of the powder mixtures and a fine dispersion of additive particles (FeF 3 ) in the MgH 2 matrix. High resolution synchrotron radiation X-ray diffraction (SR-XRD) data followed by Rietveld refinements showed a significant reduction on crystallite size for the samples containing fluorides (11 nm) in comparison with the pure MgH 2 sample (29 nm). This was related to the mechanical behavior of fluorides during milling with MgH 2 , which act as a lubricant, dispersing and/or cracking agent during milling, and thus helping to further reduce MgH 2 particle size. DSC analysis revealed that fluorides (NbF 5 , FeF 3 ) are much more effective than oxides (Nb 2 O 5 , Fe 2 O 3 ) and the transition metals (Nb and Fe), respectively, in reduction the desorption temperature. Furthermore, Nb 2 O 5 is more efficient than Fe 2 O 3 . Finally, the best results for desorption kinetics were observed for the fluorides: NbF 5 and FeF 3 (equivalent effect and consistent to the DSC analysis) followed by the oxides: Nb 2 O 5 , Fe 2 O 3 and Nb. The addition of Fe was not efficient in comparison with the pure cryomilled sample.

Cold rolling can significantly increase hydrogen storage properties of Mg and its alloys. Therefore in this paper, two important cold rolling processing parameters were investigated: the amount of passes and the roll rotation frequency, which directly influence particle and crystallite sizes and thus the interfaces for hydrogenation/dehydrogenation. Extensive cold rolling was conducted with MgH2 powder as starting material under an argon atmosphere to avoid contamination. The results indicate that the cold rolled MgH2 was free from oxides even after 50 cold rolling passes. Additionally, considerable improvements in the hydrogen storage properties were achieved with higher amounts of cold rolling passes. A similar effect could also be found for higher roll rotating frequency. This beneficial outcome originated from three important aspects: the decrease of the crystallite size reaching 88% reduction after 50 passes and 82% after 35 passes with rotating frequency of 50 rpm, the refinement of particle size, and a change in the morphology of the initial MgH2 powder from granules to flakes, and ultimately to small particles.

O desenvolvimento de tanques solidos para armazenagem de hidrogenio utilizando hidretos metalicos, como o MgH2 e uma alternativa interessante para uma matriz energetica sustentavel e renovavel. Este material apresenta pontos atrativos para diferentes escalas de aplicacoes, como uma alta densidade volumetrica de energia, alem de possuir um baixo custo como metal de partida. Por outro lado, seu processamento para a fabricacao de tanques, utiliza uma etapa de moagem de alta energia, sendo muito custoso e produzindo pos muito refinados, reduzindo sua resistencia a contaminacao pelo ar. Dessa forma, existe uma necessidade real de se buscar rotas alternativas de processamento para a fabricacao de ligas a base de Mg para armazenagem de hidrogenio. Esta pesquisa busca avaliar a viabilidade da preparacao de nanocompositos a base de Mg com a adicao de LaNi5, com microestrutura refinada e baixa area superficial especifica, por meio da consolidacao a frio seguida de laminacao a frio, combinada com uma etapa curta de moagem. Duas formas distintas do aditivo LaNi5 sera testada: o LaNi5 adquirido de baterias descartadas de Ni-HM em duas condicoes distintas: boa e pessima condicao eletroquimica. Tambem sera avaliado as propriedades de armazenagem de hidrogenio, nas etapas de absorcao/dessorcao pela rede, comparando com os diferentes tipos de materiais obtidos por laminacao a frio e estabelecendo novas correlacoes entre as condicoes de processamento, estrutura e propriedades dessas ligas.

Investiga-se nesta pesquisa a obtencao de nanocompositos a base de Magnesio-Niquel atraves da combinacao dos processos de Moagem de Alta Energia (MAE) e Laminacao a Frio (CR (Cold Rolling)), buscando-se atingir bons resultados atraves de um processamento mais rapido frente aos metodos atuais, tornando a tecnica mais viavel para a implementacao em escala industrial. Juntamente a esta acao, verificou-se o comportamento cinetico das amostras em relacao a variacao de proporcao do Ni dentro da liga.

Submitted by Alan Ricardo Floriano Bigeli (alan.rfb@gmail.com) on 2019-12-16T02:47:50Z No. of bitstreams: 1 bigeli_dissertação_magritte.pdf: 4045467 bytes, checksum: bd3360b36646905e7deba7dd9949240a (MD5) Approved for entry into archive by Maria Luiza Carpi Semeghini (luiza@assis.unesp.br) on 2019-12-16T13:06:07Z (GMT) No. of bitstreams: 1 bigeli_arf_me_assis.pdf: 4045467 bytes, checksum: bd3360b36646905e7deba7dd9949240a (MD5) Made available in DSpace on 2019-12-16T13:06:07Z (GMT). No. of bitstreams: 1 bigeli_arf_me_assis.pdf: 4045467 bytes, checksum: bd3360b36646905e7deba7dd9949240a (MD5) Previous issue date: 2019-11-14 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) O pintor belga René Magritte provoca nossa subjetividade com uma série de inquietações amparadas na realidade cotidiana. Ele se dedica a encontrar sua resolução pictórica para problemáticas das relações aparentemente banais, mas que apresentam aspectos estranhamente misteriosos. Aqui propomos aproximações entre a obra de Magritte e a Psicanálise, compreendendo as singularidades poéticas e subjetivas do pintor, introduzidas pelo termo emoção estética. Primeiramente, mostramos as diferentes perspectivas do Surrealismo na França e na Bélgica, fazendo uma incursão na vida e obra de Magritte. A seguir, estruturamos uma discussão metodológica para delimitar nosso campo de trabalho. Propomos, desse modo, análises críticas entre as obras de Magritte e as temáticas do Olhar, do Estranhamento e da Representação, adensadas pelo campo da psicanálise em consonância com as reflexões estéticas, com toque da fenomenologia. Por fim, concluímos com uma convergência entre primazia afetiva, na teoria psicanalítica, com as emoções estéticas, propostas por Magritte, constituindo aberturas sensíveis para além do estado de suspensão provocado entre a Arte e os processos de subjetivação. The Belgian painter René Magritte provokes our subjectivity with a series of concerns based on everyday reality. He is dedicated to finding his pictorial resolution to problems of apparently trivial relations, but which have strangely mysterious aspects. Here we propose approximations between Magritte's work and Psychoanalysis, understanding the painter's poetic and subjective singularities, introduced by the term aesthetic emotion. We designed a methodological discussion to deepen the field of aesthetic reflections with psychoanalysis. Then we show the different perspectives of Surrealism in France and Belgium. We also propose critical analyzes between Magritte's works and the themes of Gaze, Strangeness and Representation, deepened by the field of psychoanalysis in line with aesthetic reflections, with a touch of phenomenology. Finally, we propose a convergence between Affection, in psychoanalytic theory, with the Aesthetic Emotions proposed by Magritte, constituting sensible openings beyond the state of suspension caused between Art and the processes of subjectivation. FAPESP: 2016/25452-0

MAX phases are a class of ternary compounds, known to exhibit combined properties of ceramics and metals. In this study, we have used the microwave (MW) and conventional (CV) heat treatments in order to synthesize the Nb 2 GeC phase starting from the mixtures of raw materials (Nb, Ge and C). The results of a detailed microstructural characterization that includes X-ray diffraction (XRD) with Rietveld refinement and scanning electron microscopy (SEM) of MW and CV treated samples are reported. The XRD patterns followed by Rietveld analysis revealed that the MW sample presents 93 vol% of Nb 2 GeC phase after 48 h of processing while the CV sample has taken 240 h to attain similar results. Rietveld analysis confirmed that the Nb 2 GeC phase has a hexagonal structure with P6 3 /mmc space group and lattice parameters of a =0.323±0.005 nm and c =1.256±0.005 nm. The crystallite size was estimated by using the Williansom-Hall method being about 75 nm and 62.5 nm for the processed samples after 240 h to CV and MW sample, respectively. SEM analysis showed the presence of a more refined microstructure and relatively lowers porosity for MW sample in comparison with CV sample. These results have indicated the high potential of microwave heating to produce MAX phases in a shorter processing time when comparing with conventional processing routes.

In this paper we report the use of a novel processing route to produce samples for use as a hydrogen carrier. ZK60 alloy was produced by induction melting and sheets taken from the melt ingot were submitted to Friction Stir Processing (FSP) and subsequent manual filing with a rasp under ambient conditions. Samples from the Base Metal As-Cast (AC) and Stir Zone (SZ) were microstructurally investigated before and after filing including the alloy in as-cast state. The results showed that before filing SZ and AC samples presented equiaxial grains with the SZ sample having a much finer microstructure compared to AC. The values of grain sizes are around 150 μm and 1–2 μm for the AC and SZ samples, respectively. After filing, both samples presented similar grain sizes of only 60 nm. Although they attained similar grain sizes, the filings from SZ were more homogeneous and presented thinner innerlayers compared to its AC counterpart. The filings taken out from the SZ presented much faster kinetics for hydrogen absorption mainly due to its thinner innerlayers and its finer second-phase particle distribution, reaching up to 4.5 wt% of hydrogen uptake against only 1.0 wt% for AC sample after 10 h of absorption in the first cycle. Both samples presented similar behavior for full discharge time. These results show the possibility of using FSP with subsequent filing as a mean to obtain materials with suitable properties for use as energy carriers with enhanced kinetics and better oxidation resistance in shorter processing times.

The purpose of this study is to evaluate the efficacy of yttria-stabilized zirconia (3Y-TZP) as an inert phase to prevent the decomposition of Bi2 V0.9 Cu0.1 O5.5 -δ (BICUVOX.1) electrolyte under reducing atmosphere. A post-mortem scanning electron microscopy (SEM) study was performed after chemical stability tests under hydrogen-rich atmosphere using a Sieverts-type apparatus. SEM results showed that BICUVOX.1 decomposition starts under a hydrogen pressure of 19.7 atm at 300°C, even in the case of the composite containing 3Y-TZP. The microstructure of BICUVOX.1 after decomposition was observed to be composed of microspheres ranging from 10 to 100 µm formed primarily of metallic bismuth. In the composite, in addition to microspheres, the microstructure contained bismuth fibers growth from the grain area of the BICUVOX.1 matrix. Despite significant surface morphological modifications, the grain-boundary-arranged 3Y-TZP particles in a BICUVOX.1-matrix composite did not result in enhanced chemical stability.

Magnesium complex hydrides are attractive for hydrogen storage applications, mainly due to their high volumetric capacities and to their relatively low cost. In this work, nanocrystalline Mg2CoH5 was synthesized with very high yields (97%) by reactive milling cobalt and magnesium under relatively mild processing conditions (30 bar of H2 pressure and 12 h of milling). The behavior of the milled Mg2CoH5 during heating was studied by a combination of several techniques including DSC, QMS, TGA and in-situ synchrotron XRD. It is shown for the first time that two different mechanisms of hydrogen desorption take place. At low temperatures (up to 325°C), some hydrogen is released by a diffusional mechanism with no change in the crystalline structure of the high temperature γ-Mg2CoH5 phase. At higher temperatures, above 325°C, the γ-Mg2CoH5 phase becomes unstable and the complex hydride decomposes into Mg, Co and H2. This is the first work to report the diffusional hydrogen desorption mechanism for the Mg2CoH5 or any other complex hydride. Furthermore, a complete description of the allotropic β-Mg2CoH5 to γ-Mg2CoH5 phase transition is provided. Fil: Zepon, G.. Universidade Federal do São Carlos; Brasil Fil: Leiva, D. R.. Universidade Federal do São Carlos; Brasil Fil: Kaufman, M. J.. Colorado School of Mines; Estados Unidos Fil: Figueroa, Santiago Jose Alejandro. Centro Nacional de Pesquisa em Energia e Materiais Rua Giuseppe Máximo Scolfaro; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Floriano, R.. Universidade Estadual de Campinas; Brasil Fil: Lamas, Diego Germán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Asselli, A. A. C.. Universidade Federal do São Carlos; Brasil Fil: Botta, W. J.. Universidade Federal do São Carlos; Brasil

Composite solid electrolytes were prepared varying the addition of yttria-stabilized zirconia (3Y-TZP) from 3 to 26 wt% using a matrix of copper-substituted bismuth vanadate (BICUVOX.1). The effects of stabilized zirconia concentration were added and their relation with the tensile strength, thermal expansion, phase transition and electrical conductivity were evaluated. When compared to pristine BICUVOX.1, the addition of 26 wt% of 3Y-TZP led to an increase of 144% in tensile strength and a reduction of the thermal expansion coefficient from 12.3×10 −6 °C −1 to 9.6×10 −6 °C −1 . Such improvements stems from grain growth inhibition due to the Zener pinning effect. Impedance measurements and thermal analyses showed that the addition of high zirconia concentrations is an effective way to prevent the γ′↔γ phase transition in the BICUVOX.1 matrix. Nevertheless, the total electrical conductivity has been continuously reduced with a progressive increase in the amount of zirconia.

In this paper the hydrogen storage properties of cold forged MgH2 were investigated. Magnesium hydride was processed in air by close-die drop forging at room temperature. The effects of processing parameters such as drop height of the hammer and number of forging passes were evaluated. The influence of final thickness of the forged samples was also studied. Cold forging of MgH2 resulted in pronounced grain refinement and enhanced hydrogen storage properties. Faster kinetics of hydrogen absorption and desorption were achieved by higher energy processing such as releasing the hammer from higher heights and increasing the number of applied forging passes. Results concerning sample thickness showed that MgO formation plays an important role to degrade both hydrogen capacity and kinetics. As a result of preferential surface oxidation of the forged MgH2, thicker samples showed better hydrogen storage properties.

A new processing route consisting of a short-time high energy ball milling (HEBM) stepfollowed by cold rolling (CR) to produce MgH 2 -based nanocomposites was investigated.Samples of pure MgH 2 and MgH 2 -mixtures containing 2 mol% of FeF 3 were processed underair atmosphere and their effects on the microstructure and the hydrogen storage proper-ties were studied in detail. X-ray Diffraction (XRD) analysis on all samples revealed crys-tallite sizes in the nanometer range for the beta-MgH 2 and FeF 3 phases (beta (beta): w8e13 nm and FeF 3 : w16e21 nm). No extra crystallite size reduction was observed for theHEBM þ CR samples in comparison with those only cold rolled. Scanning electron micro-scopy (SEM) evaluation together with elemental composition analysis indicated a finer sizedistribution of additive particles and also a more intimate level of mixing for theHEBM þ CR mixture than for the mixture obtained only by CR. These features were asso-ciated with the HEBM step applied before the CR. These characteristics led to a lowerhydrogen desorption temperatures and enhanced desorption kinetics behavior for theHEBM þ CR samples in comparison with the CR samples.Copyright a 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rightsreserved.

In the present work, we report results from a new processing route for Mg: cold rolling under inert atmosphere, followed by a short-time HEBM step (CR + HEBM). This processing route is presented as a powerful tool to reduce the activation time for Mg hydrogenation samples with no need to introduce any additives. Mg samples were extensively processed by CR and CR + HEBM and their effects on the microstructure and hydrogen storage properties were studied. The Mg samples processed by CR + HEBM presented refined microstructure (grain sizes around 4–7 nm), strong texture and are certainly free of oxide layer formation. These conditions lead to relatively fast activation kinetics and enhanced kinetics behavior that has not been reported in the literature so far.