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Ma, Hongqiang, Kun Lin, Longlong Fan, Yangchun Rong, Jun Chen, Jinxia Deng, Laijun Liu, Shogo Kawaguchi, Kenichi Kato i Xianran Xing. "Structure and oxide ion conductivity in tetragonal tungsten bronze BaBiNb5O15". RSC Advances 5, nr 88 (2015): 71890–95. http://dx.doi.org/10.1039/c5ra10635d.
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Tetragonal tungsten bronze compound, BaBiNb5O15, is found to be a new type of oxide ion conductor with a total electrical conductivity of 3 × 10−4 S cm−1 at 600 °C.
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Jouffret, Laurent, Jerome Lhoste, Annie Hemon-Ribaud, Marc Leblanc i Vincent Maisonneuve. "(H3O)2NaAl3F12, isostructural with A 2NaAl3F12 (A = K+, Rb+, Cs+) fluorides having HTB-type sheets". Acta Crystallographica Section C Structural Chemistry 70, nr 5 (30.04.2014): 512–16. http://dx.doi.org/10.1107/s205322961400919x.
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The title compound, (H3O)2NaAl3F12 [dihydronium sodium trialuminum(III) dodecafluoride], was obtained by solvothermal synthesis from the reaction of aluminium hydroxide, sodium hydroxide, 1,2,4-triazole and aqueous HF in ethanol at 463 K for 48 h. The structure consists of AlF6 octahedra organized in [AlF4 −] n HTB-type sheets (HTB is hexagonal tungsten bronze) separated by H3O+ and Na+ cations.
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Guyot, H., H. Balaska i J. Marcus. "Electronic structure of the Peierls compound K0.9Mo6O17". Journal de Physique IV 12, nr 9 (listopad 2002): 95–96. http://dx.doi.org/10.1051/jp4:20020368.
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The purple potassium bronze of molybdenum is a quasi two-dimensional compound showing a Peierls transition at 120 K. This transition is driven by the properties of the conduction electrons. In order to confirm the nature of the transition, we have investigated at room temperature the electronic structure of this oxide and established its band structure in the ΓK direction. A weak conduction band is detected, well separated from the valence band by a depleted region. The valence band shows several structures attributed to oxygen-type states and to the K3p shallow core level. The structures of the conduction band reveal the presence of at least two bands crossing the Fermi level, in relatively good agreement with the calculated band structure.
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Roussel, P., G. Mather, B. Domengès, D. Groult i P. Labbé. "Structural Investigation of P4W24O80: A New Monophosphate Tungsten Bronze". Acta Crystallographica Section B Structural Science 54, nr 4 (1.08.1998): 365–75. http://dx.doi.org/10.1107/s0108768197013785.
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The crystallographic study of the tungsten phosphate bronze P4W24O80 was performed from three-dimensional single-crystal X-ray diffraction data and electron microscopy. This compound crystallizes in the orthorhombic system with unit-cell dimensions a = 5.312 (1), b = 6.5557 (8), c = 42.196 (8) Å and space group P212121. The crystal structure was solved by direct methods and Fourier techniques, and refined to the reliability factor R = 0.0284 (wR = 0.0272). Its determination confirms that it belongs to the monophosphate tungsten bronze family of the general formula (PO2)4(WO3)2m with the value m = 12. Large empty cages surrounded by 18 O atoms are built up of eight WO6 octahedra and four PO4 tetrahedra sharing corners. They are located between two WO3-type slabs forming pentagonal-shaped tunnels running in the a direction. Electron microscopy investigations confirm that the studied crystal does not imply modulation phenomena when other crystals of the same composition exhibit satellite reflections with a modulation vector q* involving a doubling of a. The observations also reveal the existence of a monoclinic form of the m = 12 compound, which is a regular intergrowth of m = 11 and m = 13 members in a similar way to the m = 5 member of the series where the same feature has already been observed. On each edge of a WO3-type slab, a large variation (from 1.73 to 2.09 Å) of the six W—O distances within the WO6 octahedron is noted, which yields an oxidation state of W near 6, whereas for the WO6 octahedra located in the middle part of the slab the six W—O distances are gathered about their mean value (1.92 Å), which involves a more important electronic delocalization. The thermal motion of the W atoms is described. The absolute structural configuration is tested on the basis of some calculated structure factors, which are more sensitive to the x, y, z → −x, −y, −z change of atomic positions.
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SAHOO, P. S., S. K. PATRI, R. N. P. CHOUDHARY i A. PANIGRAHI. "STRUCTURAL AND DIELECTRIC PROPERTIES OF Ba2Sr3SmTi3V7O30". Modern Physics Letters B 22, nr 30 (10.12.2008): 2999–3005. http://dx.doi.org/10.1142/s0217984908017448.
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The polycrystalline sample of Ba 2 Sr 3 SmTi 3 V 7 O 30, a member of the tungsten bronze structural family, was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction analysis suggests the formation of a single-phase compound with orthorhombic structure. Detailed studies of the dielectric constant and tangent loss as a function of frequency (100 Hz to 1 MHz) and temperature (32°–500°C) show that this compound has a diffused-type of ferroelectric phase transition at 230°C. Study of the surface morphology by SEM showed uniform grain distribution on the surface of the sample with less porosity. The activation energy, calculated from the plot of temperature dependence of AC conductivity, of the compound was found to be 0.11 eV and 0.14 eV at 500 kHz and 1 MHz respectively. The nature of the variation of conductivity and value of activation energy suggest that the conduction process is of a mixed-type.
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Babaryk, A. A., I. V. Odynets, S. Khainakov i N. S. Slobodyanik. "Synthesis and X-ray powder diffraction data of Ba2.64Ta11.25O30.81". Powder Diffraction 29, nr 4 (15.10.2014): 385–88. http://dx.doi.org/10.1017/s0885715614000748.
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The Ba2.64Ta11.25O30.81was prepared by conventional solid-state reaction technique as a single phase. It was found that the compound crystallizes in the tetragonal system, space group P4/mbm (No. 127) and unit-cell parameters are a = 12.508 59(8) Å, c = 3.912 81(2) Å, V = 612.218(7) Å3, and Z = 1. The crystal structure of the Ba2.64Ta11.25O30.81 phase is found to be closely related to the tetragonal tungsten bronze structure type, comprising interstitial (TaO)+ inclusions. Reference data were derived from the Rietveld analysis and reported here.
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Chebabe, Driss, Ahmed Dermaj, Hamid Erramli i Najat Hajjaji. "Corrosion inhibition of bronze alloy B66 by 4-amino-3-methyl-1,2,4-triazole-5-thione in 3 per cent NaCl solution". Anti-Corrosion Methods and Materials 61, nr 5 (26.08.2014): 281–86. http://dx.doi.org/10.1108/acmm-05-2013-1265.
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Purpose – The purpose of this study is to study corrosion inhibition of Bronze alloy B66 by 4-amino-3-methyl-1,2,4-triazole-5-thione (MTSNH) in 3 per cent NaCl solution. Archaeological bronze artefacts often are stored or displayed in uncontrolled conditions and may suffer from dangerous active corrosion processes that can lead to their destruction. The most dangerous form of archaeological bronze degradation is due to a cyclic reaction that involves copper from the pure alloy and chlorine as a pathogenic agent. A protection treatment can be used to protect them from the corrosion environment and stabilise them to avoid further degradation during exhibition or storage. Starting from its initial assessment as a corrosion inhibitor for pure copper, nowadays benzotriazole (BTA) is in widespread use for the conservation of copper-based artefacts, but unfortunately, BTA is toxic and a suspected carcinogen. The development of new and safe protection systems would offer a choice of alternative products to conservation-restoration professionals for the effective and safe stabilization and protection of metal artefacts. In this investigation, a new organic compound, namely, MTSNH, was synthesized, characterized and tested as a corrosion inhibitor for Bronze B66 (similar to archaeological bronze) in 3 per cent NaCl solution using potentiodynamic polarization studies and electrochemical impedance spectroscopy (EIS) at room temperature. It has been observed from the corrosion rate that the inhibition efficiency increased with increasing concentration of MTSNH. Potentiodynamic polarisation results revealed that the compound acted as a mixed-type inhibitor. Impedance studies indicated that protection occurs through adsorption of the inhibitor on the metal surface, with important modification to the mechanism of corrosion. Surface analysis was carried out using scanning electron microscopy scanning electron microscopy (SEM)/energy dispersive spectrometry (EDX) techniques to verify the electrochemical results. Design/methodology/approach – The inhibition efficiency of MTSNH is investigated by potentiodynamic polarization, EIS and surface analysis. Findings – The synthesized MTSNH act a good inhibitor in 3 per cent NaCl and inhibition efficiency increases with inhibitor concentration. Polarisation curves showed that the inhibitor is mixed. The EIS measurements showed that the inhibitor acted throughout the formation of film at the bronze surface. The surface analysis confirms this result. Originality/value – The adsorption of the MTSNH on the metal surface can markedly change the corrosion resisting property of metal. Therefore, the study of the relation between adsorption and corrosion inhibiting is of a great importance.
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BEHERA, BANARJI, P. NAYAK i R. N. P. CHOUDHARY. "IMPEDANCE SPECTROSCOPY STUDY OF NaCa2Nb5O15 CERAMICS". Modern Physics Letters B 23, nr 01 (10.01.2009): 97–109. http://dx.doi.org/10.1142/s0217984909017765.
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Polycrystalline sample of NaCa 2 Nb 5 O 15 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray structural analysis exhibits the orthorhombic crystal structure of the compound at room temperature. Detailed dielectric studies of NaCa 2 Nb 5 O 15 over a wide range of temperature (31–500°C) and frequency (102–106 Hz) did not show any dielectric anomaly (or ferroelectric phase transition) as observed in other members of the tungsten bronze structural family. However, the low loss tangent and dielectric constant increase with increasing temperature. Complex impedance and modulus plots (at different temperature and frequency) show the existence of non-Debye type of relaxation process in the compound. Complex modulus spectrum shows only grain contribution in the compound. Electric modulus analysis suggests that a possible hopping mechanism is evident for electrical transport processes in the system. Studies of AC conductivity with frequency suggest that the material obeys Jonscher's universal power law.
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Jin, Xingxing, Lijie Luo, Yongjun Chen, Jianbao Li i Chunfu Lin. "BiNb5.4O15: A new Li+-storage material with a tetragonal tungsten bronze crystal structure". Functional Materials Letters 14, nr 02 (luty 2021): 2150005. http://dx.doi.org/10.1142/s1793604721500053.
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Niobates with tungsten bronze crystal structures are regarded as prospective Li[Formula: see text]-storage anode candidates due to the rich chemistry of niobium and structural openness. However, the exploration of this type of materials is still insufficient. Here, BiNb[Formula: see text]O[Formula: see text] with a tetragonal tungsten bronze crystal structure (Cmmm space group) is explored. Abundant large-sized tunnels and a large interlayer spacing of [Formula: see text]3.97 Å are found in this open structure, enabling fast Li[Formula: see text] diffusivity (3.25 × 10[Formula: see text]/1.68 × 10[Formula: see text] cm2 ⋅ s[Formula: see text] during lithiation/delithiation). Additionally, this structure is very stable after the first lithiation process, resulting in excellent cyclability (95.4%/[Formula: see text]100% capacity retention after 100/1000 cycles at 1C/10C). BiNb[Formula: see text]O[Formula: see text] further exhibits a safe Li[Formula: see text]-storage potential ([Formula: see text]1.55 V) and a large reversible capacity (309.7 mAh ⋅ g[Formula: see text]@ 0.1C). Therefore, BiNb[Formula: see text]O[Formula: see text] can be a practical Li[Formula: see text]-stora ge anode compound for large-scale energy-storage applications.
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Islak, S., D. Kir i H. Çelik. "Investigation of the Usability of Cubic Boron Nitride Cutting Tools as an Alternative to Diamond Cutting Tools for the Aircraft Industry". Archives of Metallurgy and Materials 58, nr 4 (1.12.2013): 1119–23. http://dx.doi.org/10.2478/amm-2013-0135.
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Abstract Diamond and cubic boron nitride (cBN) cutting segments were produced using hot pressing technique for this study to be used in cutting natural stone. cBN grains were added to bronze powder, the chosen matrix, at a rate of 0%, 20%, 40%, 60%, 80%, and 100% (according to percentage by weight). Segments were produced under a pressure of 35 MPa, at a sintering temperature of 600°C, over a sintering time of 3 minutes. The cutting properties of the produced segments were determined by cutting Ankara andesite. A Scanning Electron Microscope (SEM) and an X-Ray Diffractometer (XRD) were used to analyse the microstructure, phase compound, and wear surfaces of each segment type.
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LaBrecque, Douglas, i William Daily. "Assessment of measurement errors for galvanic-resistivity electrodes of different composition". GEOPHYSICS 73, nr 2 (marzec 2008): F55—F64. http://dx.doi.org/10.1190/1.2823457.
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This research provides an empirical study of electrodes used to measure galvanic resistivity. The central element of this work is an estimation of errors in resistivity measurements that arise because of the type of electrode material used. Fourteen types of electrodes were tested including metal electrodes, metal-salt-compound (nonpolarizing) electrodes, and one nonmetal electrode, under conditions that are typical of those encountered during geophysical surveys. Measurement errors for resistance and chargeability were estimated using the reciprocity of data from an array of electrodes such as might be used for electric-resistance tomography. The same error analysis was applied to data from a network of high-precision resistors to separate instrument errors from electrode errors. Significant differences were observed in errors produced by different electrode materials. We conclude that the choice of electrode is very important for resistivity or chargeability surveys. Iron, steel (including rebar), lead, and phosphor bronze produced the smallest errors in resistance and chargeability. Aluminum, magnesium, titanium, copper, and zinc produced the largest errors. Stainless steel (alloy 316), tin, and brass performed reasonably well, as did carbon, which was the only nonmetal tested.
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Fukada, Shigeo, Kentaro Nishimura i Tomoaki Matsuda. "Modelling and Control of Flexure Mechanism Driven by Electromagnetic Linear Motors for Ultraprecise Continuous Path Positioning over a One-Millimetre Stroke". International Journal of Automation Technology 5, nr 6 (5.11.2011): 809–22. http://dx.doi.org/10.20965/ijat.2011.p0809.
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The topic discussed is the Continuous-Path (CP) control performance of a planar positioning mechanism with three degrees of freedom using flexure guides and electromagnetic linear motors. A stage of cube configuration with 60 mm sides is supported by leaf springs made of phosphor bronze, which form double compound rectilinear springs with three degrees of freedom. Three pairs of VCM-type linear motors are set around the stage, and laser interferometers with a resolution of 0.6 nm measures the stage motion in the X-Y-θ directions. To achieve ultraprecise CP positioning, a dynamic model is derived from the equations of motion of the mechanism, and a simulation system is constructed to demonstrate the dynamic performance of the developed positioning system. Some experiments are performed to evaluate the performance of the control methods to obtain high-precision circular motion. The simulation system reproduces the performance in single-axis positioning. The multiaxis control is affected by interference among the axes X-Y-θ. To eliminate the interference, the input-output property of the mechanismconsidered as a Multiple-Input Multiple-Output (MIMO) system is measured in quasi-static and dynamic domains, and a static inverse model of the MIMO system is adopted for a FeedForward (FF) controller. Fine circularmotion with a roundness of 66 nm and a tracking deviation of 20 nm is achieved over a 1-mm stroke, and thus, the potential of the mechanism is demonstrated.
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Jiménez Ávila, Javier. "Un conjunto de arreos de bronce de la colección Juan Cabré: aportaciones al estudio del atalaje ecuestre en la Protohistoria Ibérica = A Set of Bronze Horse Bits in the Juan Cabré Museum: A Contribution to the Study of Equestrian Harness in Iberian Iron Age". Espacio Tiempo y Forma. Serie I, Prehistoria y Arqueología, nr 11 (11.12.2018): 49. http://dx.doi.org/10.5944/etfi.11.2018.21188.
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Se estudia un conjunto de objetos formado por dos embocaduras de caballo y dos camas laterales de bronce conservados en el Museo Juan Cabré de Calaceite (Teruel). Corresponden a la colección que reunió D. Juan Cabré Aguiló y que, a su muerte, fue dividida entre sus dos hijos. No se conocen datos acerca de su procedencia ni sobre el modo en que llegaron los objetos a la colección, pero la calidad del material y la escasez de este tipo de productos en la arqueología peninsular elevan su interés. De su estudio se deriva su relación con un conjunto de arreos que se producen y se usan en la península ibérica a finales de la I Edad del Hierro y que cuenta con buenas representaciones en la Extremadura post-orientalizante y en la Alta Andalucía ibérica, particularmente en la zona de Jaén.An equestrian set composed by two bronze horse bits and two bit guards, also made in bronze, is studied. They are preserved in the Juan Cabré Museum (Calaceite, Spain) corresponding to the collection gathered by the Spanish archaeologist Juan Cabré Aguiló (1882-1947). Data about origin or the way that such objects came to the Cabré Collection are unknown, but their quality and the shortage of this type of objects in the Iberian archaeology underline their interest. The study shows a near relationship with a kind of bronze harnesses that were produced and used in Iberian Peninsula at the end of the Early Iron Age. This kind of bits have good references in the post-Orientalizing Extremadura and in the Iberian high Andalusia, particularly in the Jaén area.
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Whittle, Thomas, i Siegbert Schmid. "Diffraction Studies of Tungsten Bronze Type Relaxor Ferroelectrics". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C78. http://dx.doi.org/10.1107/s2053273314099215.
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Ferroelectric materials are essential for modern electronic applications, from consumer electronics to sophisticated technical instruments. Relaxor ferroelectric materials provide the advantage of high dielectric constants over broad temperature ranges not seen in traditional ferroelectrics. Tungsten bronze type compounds have been shown to display a variety of industrially relevant optical and electronic properties amongst others. There is a fundamental relationship between the physical properties displayed by ferroelectrics and the crystal structures in which they form. Of particular interest are compositions and temperatures near phase transition. These are import because near phase transitions, particularly morphotropic phase transitions, electromechanical properties are often dramatically enhanced. [1,2] This work focuses on the structural investigation of the tungsten bronze type relaxor ferroelectric materials in the BaxSr3-xTi1-yZryNb4O15 (0 ≤ x ≤ 3; 0 ≤ y ≤ 1) system. A combination of X-ray, neutron (ToF and constant wavelength) and electron diffraction were employed to map the entire room temperature phase space. In addition, morphotropic phase boundary compositions were determined accurately. Variable temperature synchrotron X-ray diffraction studies were utilised to further explore the phase diagram for non-ambient conditions. Temperature dependent phase transitions were determined and the relationship between composition and transition temperature analysed. Structural models used in this work resulted from Rietveld refinements against powder diffraction data. [3] This work will shed light on new lead free relaxor ferroelectric materials.
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Ciurdas, Mariana, Ioana Arina Gherghescu, Sorin Ciuca, Alina Daniela Necsulescu, Cosmin Cotrut i Ruxandra Elena Dumitrescu. "Heat Treatment Influence on the Corrosion Resistance of a Cu-Al-Fe-Mn Bronze". Revista de Chimie 69, nr 5 (15.06.2018): 1055–59. http://dx.doi.org/10.37358/rc.18.5.6260.
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Aluminium bronzes are exhibiting good corrosion resistance in saline environments combined with high mechanical properties. Their corrosion resistance is obviously confered by the alloy chemical composition, but it can also be improved by heat treatment structural changes. In the present paper, five Cu-Al-Fe-Mn bronze samples were subjected to annealing heat treatments with furnace cooling, water quenching and water quenching followed by tempering at three different temperatures: 200, 400 and 550�C. The heating temperature on annealing and quenching was 900�C. The structure of the heat treated samples was studied by optical and scanning electron microscopy. Subsequently, the five samples were submitted to corrosion tests. The best resistance to galvanic corrosion was showed by the quenched sample, but it can be said that all samples are characterized by close values of open-circuit potentials and corrosion potentials. Concerning the susceptibility to other types of corrosion (selective leaching, pitting, crevice corrosion), the best corrosion resistant structure consists of a solid solution, g2 and k compounds, corresponding to the quenched and 550�C tempered sample.
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Bouziane, M., M. Taibi i A. Boukhari. "Synthesis and ferroelectric properties of rare earth compounds with tungsten bronze-type structure". Materials Chemistry and Physics 129, nr 3 (październik 2011): 673–77. http://dx.doi.org/10.1016/j.matchemphys.2011.06.009.
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KLIMOVA, I. P., V. I. VORONKOVA i V. K. YANOVSKII. "ChemInform Abstract: Novel Compounds ABnW3-nO9 with a Hexagonal Tungsten Bronze Type Structure". ChemInform 26, nr 32 (17.08.2010): no. http://dx.doi.org/10.1002/chin.199532021.
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Whittle, Thomas A., i Siegbert Schmid. "Structural investigation of tungsten bronze-type relaxor ferroelectrics in the BaxSr3−xTiNb4O15 system". Powder Diffraction 29, S1 (10.11.2014): S15—S18. http://dx.doi.org/10.1017/s0885715614000980.
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Compounds in the BaxSr3−xTiNb4O15 series with x = 0.0–3.0 were synthesised. Synchrotron X-ray diffraction data were collected for each member synthesised. Rietveld refinements were performed for all compositions. A composition-dependent phase transition between orthorhombic and tetragonal symmetries was found. Cation ordering was observed between barium and strontium atoms in the two distinct A site cavities
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Ishida, Kohdai, Yuya Ikeuchi, Cédric Tassel, Hiroshi Takatsu, Craig M. Brown i Hiroshi Kageyama. "High-Pressure Synthesis of Non-Stoichiometric LixWO3 (0.5 ≤ x ≤ 1.0) with LiNbO3 Structure". Inorganics 7, nr 5 (12.05.2019): 63. http://dx.doi.org/10.3390/inorganics7050063.
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Compounds with the LiNbO3-type structure are important for a variety of applications, such as piezoelectric sensors, while recent attention has been paid to magnetic and electronic properties. However, all the materials reported are stoichiometric. This work reports on the high-pressure synthesis of lithium tungsten bronze LixWO3 with the LiNbO3-type structure, with a substantial non-stoichiometry (0.5 ≤ x ≤ 1). Li0.8WO3 exhibit a metallic conductivity. This phase is related to an ambient-pressure perovskite phase (0 ≤ x ≤ 0.5) by the octahedral tilting switching between a−a−a− and a+a+a+.
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Jaksic, Jelena, Diamantoula Labou i Georgos Papakonstantinou. "Phenomena and significance of intermediate spillover in electrocatalysis of oxygen and hydrogen electrode reactions". Chemical Industry 66, nr 4 (2012): 425–53. http://dx.doi.org/10.2298/hemind110826005j.
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Altervalent hypo-d-oxides of transition metal series impose spontaneous dissociative adsorption of water molecules and pronounced membrane spillover transferring properties instantaneously resulting with corresponding bronze type (Pt/HxWO3) under cathodic, and/or its hydrated state (Pt/W(OH)6) responsible for the primary oxide (Pt-OH) effusion, under anodic polarization, this way establishing instantaneous reversibly revertible alterpolar bronze features (Pt/H0.35WO3 Pt/W(OH)6), and substantially advanced electrocatalytic properties of these composite interactive electrocatalysts. As the consequence, the new striking and unpredictable prospects both in law and medium temperature proton exchange membrane fuell cell (L&MT PEMFC) and water electrolysis (WE) have been opened by the interactive supported individual (Pt, Pd, Ni) or prevailing hyper-d-electronic nanostructured intermetallic phase clusters (WPt3, NbPt3, HfPd3, ZrNi3), grafted upon and within high altervalent capacity hypo-d-oxides (WO3, Nb2O5, Ta2O5, TiO2) and their proper mixed valence compounds, to create a novel type of alterpolar interchangeable composite electrocatalysts for hydrogen and oxygen electrode reactions. Whereas in aqueous media Pt (Pt/C) features either chemisorbed catalytic surface properties of H-adatoms (Pt-H), or surface oxide (Pt=O), missing any effusion of other interacting species, new generation and selection of composite and interactive strong metal-support interaction (SMSI) electrocatalysts in condensed wet state primarily characterizes interchangeable extremely fast reversible spillover of either H-adatoms, or the primary oxides (Pt-OH, Au-OH), or the invertible bronze type behavior of these significant interactive electrocatalytic ingredients. Such nanostructured type electrocatalysts, even of mixed hypo-d-oxide structure (Pt/H0.35WO3/TiO2/C, Pt/HxNbO3/TiO2/C), have for the first time been synthesized by the sol-gel methods and shown rather high stability, electron conductivity and non-exchanged initial pure mono-bronze spillover and catalytic properties. The underpotential spillover double layer (DL) charging and discharging properties of the primary oxide (M-OH), interrelated with the interactive self-catalytic effect of dipole-oriented water molecules, has also been proved and pointed out as the phenomenological appearance and aspect of the interactive spillover featuring intermediates. In fact, phenomenological aspects of spillover for the main reacting intermediate species in oxygen and hydrogen electrode reactions along with earned and withdrawn theoretical knowledge represent the basic concepts and aims of the present study.
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Shakil, Md Mahbubur R., Tapas Debnath, Claus H. Ruscher i Altaf Hussain. "Study of Tantalum Substituted Potassium Tungsten Bronzes". Journal of the Bangladesh Chemical Society 25, nr 1 (3.09.2012): 38–45. http://dx.doi.org/10.3329/jbcs.v25i1.11770.
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A series of compounds KxTayW1-yO3 with x = 0.30, 0.00 ? y ? 0.30 and x = 0.55, 0.00 ? y ? 0.10 were synthesized by conventional solid-state method. The samples were characterized using XRD and FTIR spectroscopy. X-ray powder patterns reveal that the samples with compositions x = 0.30, y ? 0.30 show hexagonal tungsten bronze (HTB) type phase and the samples with x = 0.55, 0.02 ? y ? 0.10 show a mixture of two phases (K-HTB and tetragonal potassium tungsten bronze, K-TTB). The samples of the system, K0.30TayW1-yO3 with 0.00 ? y ? 0.15 shows no significant change in the cell parameters. However, for the composition y > 0.15, the cell parameter a decreases and c increases with increasing Ta content, which may be explained by the ordering of Ta for y > 0.15 suggesting the transformation to another space group. The appearance of absorption peak in the infrared absorption spectra of K0.3TayW1-yO3, y > 0.10 samples indicate the transition to non-metallic phase. DOI: http://dx.doi.org/10.3329/jbcs.v25i1.11770 Journal of Bangladesh Chemical Society, Vol. 25(1), 38-45, 2012
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WANG, Jui-Kai, Naoki WAKIYA, Kazuo SHINOZAKI i Nobuyasu MIZUTANI. "Morphotropic Phase Boundary (MPB) of Tungsten Bronze Type New Compounds (Pb1-xLa2x/3)5Nb10O30 (X=0.0-0.50)." Journal of the Ceramic Society of Japan 108, nr 1261 (2000): 785–89. http://dx.doi.org/10.2109/jcersj.108.1261_785.
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Roussel, P., O. Pérez i Ph Labbé. "Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors". Acta Crystallographica Section B Structural Science 57, nr 5 (29.09.2001): 603–32. http://dx.doi.org/10.1107/s0108768101009685.
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Phosphate tungsten bronzes have been shown to be conductors of low dimensionality. A review of the crystallographic and structural properties of this huge series of compounds is given here, corresponding to the present knowledge of the different X-ray studies and electron microscopy investigations. Three main families are described, monophosphate tungsten bronzes, Ax (PO2)4(WO3)2m , either with pentagonal tunnels (MPTBp) or with hexagonal tunnels (MPTBh), and diphosphate tungsten bronzes, Ax (P2O4)2(WO3)2m , mainly with hexagonal tunnels (DPTBh). The general aspect of these crystal structures may be described as a building of polyhedra sharing oxygen corners made of regular stacking of WO3-type slabs with a thickness function of m, joined by slices of tetrahedral PO4 phosphate or P2O7 diphosphate groups. The relations of the different slabs with respect to the basic perovskite structure are mentioned. The structural description is focused on the tilt phenomenon of the WO6 octahedra inside a slab of WO3-type. In this respect, a comparison with the different phases of the WO3 crystal structures is established. The various modes of tilting and the different possible connections between two adjacent WO3-type slabs involve a great variety of structures with different symmetries, as well as the existence of numerous twins in MPTBp's. Several phase transitions, with the appearance of diffuse scattering and modulation phenomena, were analysed by X-ray scattering measurements and through the temperature dependence of various physical properties for the MPTBp's. The role of the W displacements within the WO3-type slabs, in two modulated structures (m = 4 and m = 10), already solved, is discussed. Finally, the complexity of the structural aspects of DPTBh's is explained on the basis of the average structures which are the only ones solved.
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Arakcheeva, A. V., G. Chapuis, V. V. Grinevich i V. F. Shamrai. "Structure type of hexagonal tantalum bronzes with variable composition K6Ta6 + Z O15F6(F, O)y: Ta(5 − δ)+ bronzes and Ta5+ compounds". Crystallography Reports 49, nr 1 (styczeń 2004): 70–85. http://dx.doi.org/10.1134/1.1643966.
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Whittle, Thomas A., Teng Lu, Peter Blanchard, James R. Hester, Qinfen Gu, Yun Liu i Siegbert Schmid. "Synthesis, structure and dielectric properties of the Sr3Ti1−xZrxNb4O15, (0 ≤ x ≤ 1), series of tungsten bronze type compounds". CrystEngComm 22, nr 30 (2020): 4994–5001. http://dx.doi.org/10.1039/d0ce00425a.
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Goudjil, Meriem, Enrique Gutiérrez-Puebla, Paola Bonazzi, Eugenio Lunedei, Djillali Mezaoui i Luca Bindi. "Synthesis and crystal structure of a series of stoichiometric (n)-ITB molybdenum-bronze oxides containing trivalent arsenic". Zeitschrift für Kristallographie - Crystalline Materials 234, nr 9 (25.09.2019): 569–79. http://dx.doi.org/10.1515/zkri-2019-0018.
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Abstract A series of six new single crystals of fully stoichiometric As3+-bearing Mo-oxides and partially W-substituted Mo-oxides with formula AsmO(Mo1−xWxO3)p (m = 1, 2; p = 5, 7, 9, 10 and 11 and 0 ≤ x ≤ 0.6) was successfully grown using vapor-phase transport in vacuo. The crystal structures were determined using single-crystal X-ray diffraction data. All these compounds exhibit acentric orthorhombic symmetry with Z = 2, and belong to the so-called (n)-ITB (intergrowth tungsten bronzes) family, with n = 2, 3, 4 and 5. The six (n)-ITB phases have the following formulae: (2)-AsMo5O16 (Pm 2a), (2)-As2Mo10O31 (Pma 2), (3)-AsMo7O22 (Pmn 21), (3)-As(Mo5.53W1.47)O22 (Pmn 21), (4)-As(Mo4.33W4.67)O28 (Pm 2a) and (5)-As(W6.63Mo4.37)O34 (Pmn 21). Their structures consist of vertex-sharing MO6 octahedral units (with M either Mo or Mo/W) connected so as to form three-dimensional frameworks. Such frameworks consist of perovskite tungsten bronzes (PTB) type slabs, from 2- to 5-octahedra wide, intergrown with single hexagonal tungsten bronzes (HTB) type slabs, stacked up to form pseudo-hexagonal tunnels along the a-axis. As3+ and additional oxygen atoms are located in off-center positions inside the tunnels, forming As–O bonds with peculiar arrangements. In particular, we obtained the first examples of structures where, besides the usual AsO3E distorted pyramidal geometry, As3+ adopts AsO4E coordination with a seesaw configuration.
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Zhang, H. X., C. H. Kam, Y. Zhou, X. Q. Han, S. D. Cheng, C. Y. Chan i Y. L. Lam. "Preparation and characterization of nanocrystalline potassium lithium niobate powders and films". Journal of Materials Research 16, nr 12 (grudzień 2001): 3609–13. http://dx.doi.org/10.1557/jmr.2001.0494.
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Potassium lithium niobate (KLN) powders and thin films were prepared from metalorganic compounds through the sol-gel process. A homogeneous and stable KLN precursor was synthesized by mixing the metal ethoxides. Powder gels were obtained through the hydrolysis of the solution by exposing it to the ambient atmosphere. Thin films were deposited on Si, SiO2/Si, and fused quartz by a spin coating technique. The pyrolysis and crystallization of KLN powders and films were investigated through the methods of differential thermal analysis, thermogravimetric analysis, x-ray diffraction, and Raman scattering spectroscopy. The results revealed that both KLN powders and films could crystallize into a tetragonal tungsten–bronze-type phase with appropriate annealing. Optical studies indicated that the films were highly transparent in the visible–near-infrared wavelength range and could support optical modes.
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Ohsato, Hitoshi, Toshiyuki Ohhashi, Susumu Nishigaki, Takashi Okuda, Kazuhiko Sumiya i Shinya Suzuki. "Formation of Solid Solutions of New Tungsten Bronze-Type Microwave Dielectric Compounds Ba6-3xR8+2xTi18O54(R=Nd and Sm, 0≤x≤1)". Japanese Journal of Applied Physics 32, Part 1, No. 9B (30.09.1993): 4323–26. http://dx.doi.org/10.1143/jjap.32.4323.
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Figueiredo, E., R. J. C. Silva, M. F. Araújo i R. Vilaça. "Microstructural characterisation of a collection of Protohistoric bronzes". Microscopy and Microanalysis 19, S4 (sierpień 2013): 109–10. http://dx.doi.org/10.1017/s1431927613001165.
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Microstructural characterisation of an archaeological collection of Protohistoric bronze artefacts attributed to around the VIII century B.C. and has been carried out using optical microscopy (OM) and scanning electron microscopy combined with energy dispersive spectroscopy (SEM-EDS). The collection was found in Medronhal cave (Condeixa-a-Nova, Portugal) and is composed by 1 fibula, 5 bracelets and 31 rings.Small areas on the surfaces of the artefacts were cleaned from corrosion and were metallographically prepared by a manual polishing with several diamond suspensions in a cotton swab until 1 micron diamond size. OM observations were performed in bright field (BF) illumination and under polarized light (Pol), in unetched and etched conditions. SEM-EDS was performed without a conductive coating for a minimum external elemental interference.OM observations allowed the study of the method and sequence of manufacture involved in the production of the various types of artefacts. Results show that the fibula and the bracelets have equiaxed (recrystallised) grain structures resulting from cyclic thermo-mechanical treatments performed to a pre-form cast bar until requested shape and surface finishing was attained. The rings, which are of diverse sizes, have various types of microstructures as a result of diverse manufacturing techniques. Some show a dendritic structure that resulted from the casting, and others show recrystallised structures that resulted from cycles of deformation and annealing procedures posterior to their casting (Figure 1).SEM-EDS analysis allowed the study of the presence of inclusions in the metallic matrix and the study of corrosion in some artefacts (Figure 2). Different types of inclusions were identified, namely copper sulphides, tin oxide, and lead rich inclusions. Both copper sulphides and lead inclusions are commonly found in archaeological bronzes, and can be a result of copper ores impurities. Tin oxide, on the other hand, is not so common, and its presence can be understood as a result of preferential oxidation of tin regarding copper during a melting or alloying operation. The study of the interface alloy/corrosion showed the presence of chlorides in internal corrosion layers, which can probably be related to an aggressiveness of the burial environment.This research work has been financed by the Portuguese Science Foundation (FCT) through the EarlyMetal project (PTDC/HIS-ARQ/110442/2008), the grant SFRH/BPD/73245/2010 (to EF) and the Strategic Project-LA25-2011-2012 (PEst-C/CTM/LA0025/2011) (to CENIMAT/I3N).
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Graetsch, Heribert A., Chandra Shekhar Pandey, Jürgen Schreuer, Manfred Burianek i Manfred Mühlberg. "Incommensurate modulation of calcium barium niobate (CBN28 and Ce:CBN28)". Acta Crystallographica Section B Structural Science 68, nr 2 (25.02.2012): 101–6. http://dx.doi.org/10.1107/s0108768111054863.
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The incommensurately modulated crystal structures of Ca0.28Ba0.72Nb2O6 (CBN28) and Ce0.02Ca0.25Ba0.72Nb2O6 (Ce:CBN28) were refined in the supercentred setting X4bm(AA0,−AA0) of the 3 + 2-dimensional superspace group P4bm(aa½,−aa½). Both compounds are isostructural with a tetragonal tungsten bronze-type structure. The modulation of CBN28 consists of a wavy distribution of Ba and Ca atoms as well as vacancies on the incompletely occupied Me2 site with 15-fold oxygen coordination. The occupational modulation is coupled with a modulation of the atomic displacement parameters and a very weak modulation of the positional parameters of Me2. The surrounding O atoms show strong displacive modulations with amplitudes up to ca 0.2 Å owing to the cooperative tilting of the rigid NbO6 octahedra. The Me1 site with 12-fold coordination and Nb atoms are hardly affected by the modulations. Only first-order satellites were observed and the modulations are described by first-order harmonics. In Ce:CBN28 cerium appears to be located on both the Me2 and Me1 sites. Wavevectors and structural modulations are only weakly modified upon substitutional incorporation of 0.02 cerium per formula unit of calcium.
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Papakonstantinou, Georgios D., Jelena M. Jaksic, Diamantoula Labou, Angeliki Siokou i Milan M. Jaksic. "Spillover Phenomena and Its Striking Impacts in Electrocatalysis for Hydrogen and Oxygen Electrode Reactions". Advances in Physical Chemistry 2011 (19.01.2011): 1–22. http://dx.doi.org/10.1155/2011/412165.
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The core subject of the present paper represents the interrelated spillover (effusion) phenomena both of the primary oxide and the H-adatoms, their theory and practice, causes, appearances and consequences, and evidences of existence, their specific properties, and their alterpolar equilibria and kinetic behavior, structural, and resulting catalytic, and double layer charging features. The aim is to introduce electron conductive and d-d interactive individual and composite (mixed valence) hypo-d-oxide compounds, of increased altervalent capacity, or their suboxides (Magnéli phases), as the interactive catalytic supports and therefrom provide (i) the strong metal-support interaction (SMSI) catalytic effect and (ii) dynamic spillover interactive transfer of primary oxides (M-OH) and free effusional H-adatoms for further electrode reactions and thereby advance the overall electrocatalytic activity. Since hypo-d-oxides feature the exchange membrane properties, the higher the altervalent capacity, the higher the spillover effect. In fact, altervalent hypo-d-oxides impose spontaneous dissociative adsorption of water molecules and then spontaneously pronounced membrane spillover transferring properties instantaneously resulting with corresponding bronze type (Pt/HxWO3) under cathodic and/or its hydrated state (Pt/W(OH)6), responsible for Pt-OH effusion, under anodic polarization, this way establishing instantaneous reversibly revertible alterpolar bronze features (Pt/H0.35WO3 Pt/W(OH)6) and substantially advanced electrocatalytic properties of these composite interactive electrocatalysts. Such nanostructured-type electrocatalysts, even of mixed-valence hypo-d-oxide structures (Pt/H0.35WO3/TiO2/C, Pt/HxNbO3/TiO2/C), have for the first time been synthesized by the sol-gel methods and shown rather high stability, electron conductivity, and nonexchanged initial pure monobronze spillover and catalytic properties. Such a unique electrocatalytic system, as the striking target issue of the present paper, has been shown to be the superior for substantiation of the revertible cell assembly for spontaneous reversible alterpolar interchanges between PEMFC and WE. The main target of the present thorough review study has been to throw some specific insight light on the overall spillover phenomena and their effects in electrocatalysis of oxygen and hydrogen electrode reactions from diverse angles of view and broad contemporary experimental methods and approaches (XPS, FTIR, DRIFT, XRD, potentiodynamic spectra, UHRTEM).
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Filipovic, Vojislav. "Early iron age burial complex from the Svrljig area". Starinar, nr 63 (2013): 209–18. http://dx.doi.org/10.2298/sta1363209f.
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In 2005, a group of objects was ploughed up, comprising a bronze openwork belt, bronze belt parts in the form of a four-spoked wheel, a bronze bell-shaped pendant, the arc of a bimetal fibula, fragment(s) of an iron sword, and part(s) of a horse's iron bit, at the Kalnica site in the village of Nisevac. According to the finder, while ploughing a field, his plough dug up several larger slab-shaped stones, beneath which were found the above objects, as well as fragments of human bones. The most important finds from the Kalnica grave are three parts of a bronze openwork belt (fig. 3a-c) and three bronze belt parts in the form of a four-spoked wheel. According to the finder, the belt was composed of three more belt links, two or three parts in the form of a wheel, and a final segment with a larger round buckle. The links of the belt were cast, with dimensions of 4.2-4.3 cm (length), 2-2.1 cm (height) and 0.6-0.7 cm (width). All three links were made in the same mold, after which they were decorated with perforations, incisions, and points in an identical manner. The circular bronze parts of the belt in the shape of a four-spoked wheel (fig. 3d-f) were cast, with a diametar of 2-2.1 cm, and their height precisely matches the links of the belt. All three circular parts were made in the same mold and then decorated with perforations, incisions, and points. One more item from this group of finds that probably belongs to the belt collection, is a bronze bell-shaped pendant (fig. 4/a), with a height of 4 cm and a diameter of 1.7-1.8 cm. A larger arc of a bimetal fibula was discovered in the grave, with its foot in the shape of an hourglass. The arc is 5.5 cm in width, decorated with dense small ribs. Part of a damaged horse's iron bit 11 x 4.3 cm in dimension was also found in the grave (fig. 4/c). The last find in this collection comprises part of a bent single-bladed iron sword, 11.9 x 4.4 cm (fig. 4/d). In this kind of bent sword, a so-called T end is usually found at the end of the handle/hilt, so we suppose that this sword had such an end. Bearing in mind the chronological classification of all finds from this destroyed grave (fig. 5), the openwork belt from Kalnica could be dated to the end of the VII or the very beginning of the VI centuries BC at the earliest. Such dating in principle agrees with the Ha C2/D1 central-European period, i.e. horizontal 2 according to R. Vasic, since other finds of openwork belts were dated to this period by the same author. Nevertheless, the type II iron bit does raise a slight doubt regarding the dating of the Kalnica belt, since according to M. Werner such belts were dominant in the Ha D2/3 period, i.e. at the end of the first half of the Vth century BC. The find of the composite belt from Kalnica raises several interesting observations. Firstly, the belt differs from most examples previously discovered on the territory of south-eastern Europe in that most belt link sets were formed in the shape of a square, with less frequent deviation regarding link dimensions, while those of the belt from Kalnica are relatively elongated. Links similar to the Kalnica elongated links have only be discovered in north Macedonia and in grave 5 of tumulus I in the Kenete site in Albania. The difference in the decoration of the belt from Kalnica compared with other belts is interesting. They are decorated with pierced triangles and perforated concentric circles, with a central point, repeated in countless combinations. Half-elliptical perforations appear for the first time on the belt from Kalnica, to some extent inexpertly carried out. Openwork belts have been discovered throughout the territory between the Timok river in Serbia and the Isker in Bulgaria, although according to recently published finds from the Trojan region in Bulgaria, that area could be extended eastward to the Rosica river. Outside these territories, more significant groupings are visible in the Vardar valley in Macedonia, as well as in an early Iron Age necropolis in the Donja dolina in northern Bosnia. The production center of these belts is connected with the Zlot group (Zlot-Sofronijevo), or with the Triballi tribe, but it could be said that in the VII and VI centuries BC such belts were also worn among their neighbors.
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Juszczyk, B., J. Kulasa, W. Malec, Sz Malara, M. Czepelak i L. Ciura. "Microstructure and Tribological Properties of the Copper Matrix Composite Materials Containing Lubricating Phase Particles". Archives of Metallurgy and Materials 59, nr 1 (1.03.2014): 365–69. http://dx.doi.org/10.2478/amm-2014-0061.
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Abstract The paper presents results of the studies into influence of individual particles of lubricating phase on microstructure and tribological properties of copper based composite materials for slide bearings. The studied material was composed of copper alloys with lubricating phase particles, e.g. in a form of graphite and glassy carbon. The metallic matrix of composite materials consisted of Cu-Sn type alloys. Production of the examined materials included processes with complete or partial participation of liquid phase and was conducted in two ways. In production of composites both classical powder metallurgy technology was applied and a method of melting with simultaneous mechanical stirring in liquid state (stir casting). Particles of lubricating phases were heated up to the temperature of 200°C and introduced into a liquid metal and then stirring process at constant rate of 1500 rpm rotational speed was applied. To improve wettability of graphite and glassy carbon particles titanium was introduced into the metallic matrix. In production of the composites by powder metallurgy methods the process consisted of mixing of bronze powders and particles of non-metallic phases and then their consolidation. Both quantitative and qualitative structure analysis of the produced composites was performed. Also through evaluation of tribological properties (friction coefficient, wear) with CSM Instruments high temperature tribometer THT was conducted.
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Rudashevsky, N. S., A. M. McDonald, L. J. Cabri, T. F. D. Nielsen, C. J. Stanley, Yu L. Kretzer i V. N. Rudashevsky. "Skaergaardite, PdCu, a new platinum-group intermetallic mineral from the Skaergaard intrusion, Greenland". Mineralogical Magazine 68, nr 4 (sierpień 2004): 615–32. http://dx.doi.org/10.1180/0026461046840208.
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AbstractSkaergaardite, PdCu, is a new mineral discovered in the Skaergaard intrusion, Kangerdlugssuaq area, East Greenland. It occurs in a tholeitiic gabbro associated with plagioclase, clinopyroxene, orthopyroxene, ilmenite, titanian magnetite, fayalite and accessory chlorite-group minerals, ferrosaponite, a member of the annite–phlogopite series, hornblende, actinolite, epidote, calcite, ankerite, apatite and baddeleyite. The mineral is found in composite microglobules composed of bornite, chalcocite, digenite, chalcopyrite, with rare cobalt pentlandite, cobaltoan pentlandite, sphalerite, keithconnite, vasilite, zvyagintsevite, (Cu,Pd,Au) and Pt-Fe-Cu-Pd alloys, unnamed PdCu3, (Pd,Cu,Sn), Au3Cu and PdAuCu. Skaergaardite occurs as droplets, equant grains with rounded outlines, subhedral to euhedral crystals and as irregular grains that vary in size from 2 to 75 μm, averaging 22 μm. It is steel grey with a bronze tint, has a black streak, a metallic lustre and is sectile. Neither cleavage nor fracture was observed. The mineral has a micro-indentation hardness of VHN25 = 257. It is isotropic, non-pleochroic and exhibits neither discernible internal reflections nor evidence of twinning. Skaergaardite varies from bright creamy white (associated with bornite and chalcopyrite) to bright white (associated with digenite and chalcocite). Reflectance values in air (and in oil) are: 58.65 (47.4) at 470 nm, 62.6 (51.1) at 546 nm, 64.1 (52.8) at 589 nm and 65.25 (53.95) at 650 nm. The average of 311 electron-microprobe analyses gives: Pd 58.94, Pt 1.12, Au 2.23, Cu 29.84, Fe 3.85, Zn 1.46, Sn 1.08, Te 0.28 and Pb 0.39, total 99.19 wt.%, corresponding to (Pd0.967Au0.020Pt0.010)Σ0.997(Cu0.820Fe0.120 Zn0.039Sn0.016Te0.004Pb0.003)Σ1.002. The mineral is cubic, space group Pm3m, a = 3.0014(2) Å, V = 27.0378 Å3, Z = 1. Dcalc is 10.64 g/cm3. The six strongest lines in the X-ray powder-diffraction pattern [d in Å (I)(hkl)] are: 2.122(100)(110), 1.5000(20)(200), 1.2254(50)(211), 0.9491(20)(310), 0.8666(10)(222), 0.8021(70)(321). The mineral has the CsCl-type structure. It is believed to be isostructural with wairauite (CoFe), synthetic CuZn (β-brass) and is structurally related to hongshiite (PtCu). Skaergaardite developed from a disordered Pd-Cu-rich metal alloy melt that had exsolved from an earlier Cu-(Fe) sulphide melt. Ordering of Pd and Cu (beginning at T ≈ 600°C) results in development of the CsCl structure from a disordered face-centred cubic structure.
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Behera, Banarji, Pratibindhya Nayak i Ram Choudhary. "Structural and electrical properties of KCa2Nb5O15 ceramics". Open Physics 6, nr 2 (1.01.2008). http://dx.doi.org/10.2478/s11534-008-0030-4.
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AbstractA polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105°C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31–500°C) and frequency (102–106 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible ‘hopping’ mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.
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Sahoo, Priyadarshini, Anuradha Panigrahi, Sunanda Patri i Rasm Choudhary. "Dielectric properties of Ba3Sr2DyTi3V7O30 ceramics". Open Physics 8, nr 4 (1.01.2010). http://dx.doi.org/10.2478/s11534-009-0130-9.
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AbstractA polycrystalline sample, Ba3Sr2DyTi3V7O30, with tungsten bronze structure was prepared by a mixed-oxide method at high temperature (950°C). Preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound was studied by scanning electron microscopy. The dielectric anomaly at 321°C may be attributed to the ferro-paraelectric phase transitions. This was also confirmed from the appearance of a hysteresis loop. The nature of variation of the ac conductivity and value of activation energy at different temperature regions, suggest that the conduction process is of mixed-type (i.e., ionic-polaronic and space charge generated from the oxygen ion vacancies).
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BRANDT, R., i HK MUELLER-BUSCHBAUM. "ChemInform Abstract: Ba4MgTa10O30 and Ba4NiTa10O30 Compounds Related to the Tetragonal Tungsten Bronze and the NaNb6O15F-Type." ChemInform 18, nr 52 (29.12.1987). http://dx.doi.org/10.1002/chin.198752035.
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Pezzotti, Giuseppe, Francesco Boschetto, Eriko Ohgitani, Yuki Fujita, Wenliang Zhu, Elia Marin, Bryan J. McEntire, B. Sonny Bal i Osam Mazda. "Silicon nitride: a potent solid-state bioceramic inactivator of ssRNA viruses". Scientific Reports 11, nr 1 (3.02.2021). http://dx.doi.org/10.1038/s41598-021-82608-3.
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AbstractSurface inactivation of human microbial pathogens has a long history. The Smith Papyrus (2600 ~ 2200 B.C.) described the use of copper surfaces to sterilize chest wounds and drinking water. Brass and bronze on doorknobs can discourage microbial spread in hospitals, and metal-base surface coatings are used in hygiene-sensitive environments, both as inactivators and modulators of cellular immunity. A limitation of these approaches is that the reactive oxygen radicals (ROS) generated at metal surfaces also damage human cells by oxidizing their proteins and lipids. Silicon nitride (Si3N4) is a non-oxide ceramic compound with known surface bacterial resistance. We show here that off-stoichiometric reactions at Si3N4 surfaces are also capable of inactivating different types of single-stranded RNA (ssRNA) viruses independent of whether their structure presents an envelop or not. The antiviral property of Si3N4 derives from a hydrolysis reaction at its surface and the subsequent formation of reactive nitrogen species (RNS) in doses that could be metabolized by mammalian cells but are lethal to pathogens. Real-time reverse transcription (RT)-polymerase chain reaction (PCR) tests of viral RNA and in situ Raman spectroscopy suggested that the products of Si3N4 hydrolysis directly react with viral proteins and RNA. Si3N4 may have a role in controlling human epidemics related to ssRNA mutant viruses.
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Broomhall-Dillard, Randy N. R., Roy G. Gordon i Valerie A. Wagner. "Volatile Liquid Precursors for the Chemical Vapor Deposition (CVD) of Thin Films Containing Alkali Metals". MRS Proceedings 606 (1999). http://dx.doi.org/10.1557/proc-606-139.
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AbstractThe first volatile, liquid compounds of alkali metals were synthesized and used for the CVD of materials containing alkali metals. Amides of the type MNR1(SiMe2R2) and MN(SiMe2R2)2 [M = Li, Na, K; R1 = t-butyl, t-amyl; R2= ethyl, n-propyl, i-propyl, n-butyl, i-butyl, n-hexyl, n-octyl] were made and characterized. The lithium amides were prepared via the deprotonation of the parent amine using butyl lithium. The sodium and potassium amides were formed by transamination of sodium amide and potassium bis(trimethylsilyl)amide with the parent amines. For example, lithium bis(ethyldimethylsilyl)amide was prepared from butyl lithium and bis(ethyldimethylsilyl)amine and was distilled as a clear, colorless liquid at 122 °C (0.2 Torr) having a viscosity of 37 cP at 40 °C. These alkali metal amides can be used as convenient liquid sources for CVD of mixed metal oxides containing alkali metals, such as the non-linear optical material lithium niobate, lithium-containing materials for battery electrodes, electrochromic tungsten bronzes, and the pyroelectric and ferroelectric material potassium tantalate.
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Jingzhou Municipal Museum. "The excavation of the Xiongjiazhong Graveyard in Jingzhou, Hubei in 2008". Chinese Archaeology 13, nr 1 (1.01.2013). http://dx.doi.org/10.1515/char-2013-0012.
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AbstractThe Xiongjiazhong Graveyard is situated on a low hill to the west of Zhangchang and Zongbei Villages in Chuandian Town, Jingzhou City, Hubei Province. It is 550m long from the north to the south and 200m wide from the west to the east and is composed of main tombs, auxiliary tombs, human victim burials, sacrificial pits and chariot-and-horse pits. From March to December 2008, the Jingzhou Municipal Museum excavated there six horse pits, three small chariot-and-horse pits, and a larger part of a large-sized chariot-and-horse pit (the “grand chariot-and-horse pit” which was numbered CHMK1 by the excavators), in which various types of chariots are orderly arranged in two rows. Judged by the unearthed bronzes and the date of the whole graveyard, the chariot-and-horse pits were probably built in the mid Warring-States Period. The grand chariot-and-horse pit at Xiongjiazhong is also the largest among those discovered so far throughout China. So its excavation is of great value to the study of the chariot system in the Warring- States Period.
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First, Grzegorz. "Polymorphic iconography common influences or individual features in the Near Eastern perspective". BAF-Online: Proceedings of the Berner Altorientalisches Forum 1 (16.01.2017). http://dx.doi.org/10.22012/baf.2016.17.
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Topic: polymorphic iconography in Egyptian religious iconography - special and separate types of mixed, theriomorphic and combined images / icons / forms, always with animal heads, double pairs of wings, phallus, and other magical symbols. Archaeological evidence: images appear on small size flat amulets, papyri fragments (also serving as amulets), bronze statuettes and magical healing statues. Textual evidence: lack of distinctive proper names Place: Egypt, without special area of provenance Date: Late Period (7th – 4th centuries BC), Ptolemaic and Roman Periods (from 4th century BC) Important terms:Pantheistic as an idea of all-embracing god (Pantheos)ba as an emanation / form / manifestation of a god, significantly associated with the image of the god. The animals were ba of gods.bau - strength, power, good and bad at the same time, affecting the whole world, and humans in particular. With the help of magic bau can be manipulated, to ensure people health and success. DeitesBes – Egyptian god – demon, present in magical context, protector of maternity, life, music, safety, with strong solar interpretation, often depicted as a dwarfTutu (Tithoes) – popular especially as Ptolemaic and Roman Egypt deity; main role was to repel negative powers and to protect people in danger; depicted as sphinx with mixed animal and magical attributesLamashtu – female Mesopotamian goddess / demon, who preys on mothers and children, depicted in magical context with animal elementsPazuzu – male Babylonian and Assyrian demonic god with rather beneficent, magical role, depicted with animal elementsNine–Shaped (Enneamorfos) – figure present in written Greek Magical Papyri, defined as composed of nine forms, especially of animal origin with magic function and Egyptian genesis Key problem: distribution of polymorphic iconography in other cultures, parallels, influences on the visual level (codification of symbols) and also on the ideological level (magical activity hidden / symbolised in a representation) Question of the talk: to define potential influences in the Near Eastern perspective - is the polymorphic idea specific to one culture or common to all ancient religious thinking about deities?