Thematische Bibliographien / Synthesis in molten salts

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Auswahl der wissenschaftlichen Literatur zum Thema „Synthesis in molten salts“

Autor: Grafiati

Veröffentlicht am 25. Mai 2024

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Zeitschriftenartikel zum Thema "Synthesis in molten salts"

Yang, Rui Song, Li Shan Cui, Yan Jun Zheng und Jin Long Zhao. „Synthesis of TiNi Particles in High Temperature Molten Salts“. Materials Science Forum 475-479 (Januar 2005): 1941–44. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.1941.

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. NiTi particles were prepared by the reaction between Ti and Ni powders in high temperature molten salts. Results of differential scanning calorimetry (DSC) confirmed the martensitic transformation of the prepared NiTi particles. Backscatter electron image of scanning electron microscopy (SEM) showed that the synthesized NiTi particles were captured by the molten salts, which revealed the mechanism of the chemical synthesis method in molten salts.

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Zhang, Jin Hua, Si Xiong, Chang Ming Ke, Hong Dan Wu und Xin Rong Lei. „Synthesis and Reaction Mechanism of Ti₃SiC₂ by Molten Salt Method from Ti-Si-Fe Alloy“. Key Engineering Materials 768 (April 2018): 159–66. http://dx.doi.org/10.4028/www.scientific.net/kem.768.159.

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Titanium silicon carbide (Ti3SiC2) were obtained by molten salt synthesis method using the Ti-Si-Fe alloy extracted from high titania blast furnace slag and natural graphite as the raw materials. The phase composition, microscopic structure of the products were characterized by powder X-ray diffraction, scanning electron microscope and transmission electron microscope. The influence of firing temperature and chloride salts species on the phase and morphology of the products were investigated. The results indicated that the synthetic temperature of Ti3SiC2 by molten salt synthesis method was about 100 °C, which was lower than that without molten salts. The “dissolution-precipitation” mechanism governed the overall molten salt synthesis process. The lamellar Ti3(Si,Al)C2 crystal growth obeyed by a two-dimensional ledge growth mechanism.

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Grabis, Jānis, Gundega Heidemane und Aija Krūmiņa. „Synthesis of NiO Nanoparticles by Microwave Assisted and Molten Salts Methods“. Key Engineering Materials 721 (Dezember 2016): 71–75. http://dx.doi.org/10.4028/www.scientific.net/kem.721.71.

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Nickel oxide nanoparticles were prepared via molten salts and microwave assisted synthesis from nickel nitrate and the parameters of obtained nanopowders were compared. NiO nanoparticles with crystallite size in the range of 6-8 nm have been prepared by combining microwave assisted treatment of Ni (NO3)2 and urea solution with calcination at 300-320 °C. Molten salts (NaNO2-NaCl) ensured direct formation of NiO from Ni (NO3)2.6H2O and salts mixture at 350 °C but crystallite size of the particles reached 51-69 nm.

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Yolshina, V. A., und L. A. Yolshina. „Electrochemical Synthesis of Graphene in Molten Salts“. Russian Metallurgy (Metally) 2021, Nr. 2 (Februar 2021): 206–12. http://dx.doi.org/10.1134/s0036029521020051.

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Kuznetsov, S. A. „Electrochemical Synthesis of Nanomaterials in Molten Salts“. Journal of The Electrochemical Society 164, Nr. 8 (2017): H5145—H5149. http://dx.doi.org/10.1149/2.0261708jes.

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Kuznetsov, S. A. „Electrochemical Synthesis of Nanomaterials in Molten Salts“. ECS Transactions 75, Nr. 15 (23.09.2016): 333–39. http://dx.doi.org/10.1149/07515.0333ecst.

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Yang, Jiarong, Wei Weng und Wei Xiao. „Electrochemical synthesis of ammonia in molten salts“. Journal of Energy Chemistry 43 (April 2020): 195–207. http://dx.doi.org/10.1016/j.jechem.2019.09.006.

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Devyatkin, S. V., O. I. Boiko, N. N. Uskova und G. Kaptay. „Electrochemical Synthesis of Titanium Silicides from Molten Salts“. Zeitschrift für Naturforschung A 56, Nr. 11 (01.11.2001): 739–40. http://dx.doi.org/10.1515/zna-2001-1107.

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Abstract Presented at the NATO Advanced Study Institute, Kas, Turkey, May 4 -14, 2001. Electrochemical synthesis of titanium silicides from chloro-fluoride melts has been investigated by thermodynamic calculation, voltammetry and electrolysis. The electrochemical synthesis of four titanium silicides (TiSi2, TiSi, Ti5Si4, Ti5Si3) was to be a one-step process, the stoichiometry of the deposited silicides being correlated with the concentration of Si and Ti ions in the melt.

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Wang, Wei, Gui Wu Liu, Guan Jun Qiao, Jian Feng Yang, Hong Wei Li und Ya Jie Guo. „Molten Salt Synthesis of Mullite Whiskers from Silicon Carbide Precursor“. Materials Science Forum 724 (Juni 2012): 299–302. http://dx.doi.org/10.4028/www.scientific.net/msf.724.299.

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Mullite whiskers were prepared from SiC powders in molten Al2(SO4)3-Na2SO4 mixture salts at different temperatures. The morphology and phase composition of resulting whiskers were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) techniques. Mullite tiny fiber clusters with diameter about 50 nanometers and lengths of over several microns were obtained in 900°C mixture molten salts system. A new oxidation-dissolution mechanism was proposed for explanation mullite whiskers growth.

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Zhao, Shi Xi, Qiang Li, Feng Bing Song, Chun Hong Li und De Zhong Shen. „Molten Salts Synthesis of Relaxor Ferroelectrics PMN-PT Powders“. Key Engineering Materials 336-338 (April 2007): 10–13. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.10.

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Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) solid solutions with composition near the morphotropic phase boundary (MPB) (33mol% PT) were successfully synthesized by the molten salt synthesis (MSS) method at 800°C for 30min using Li2SO4-Na2SO4 and NaCl-KCl molten salts as a medium of reaction, respectively. The influences of processing parameters, such as temperature, time, and type of salts, on the formation and the micrographs characteristics of the PMN-PT powders were discussion. It was found that the PMN-PT powder obtained by the MSS method has a relatively uniform size distribution and a better dispersivity of particle, and an average size of PMN-PT particles with smooth surface was around 0.3∼0.5 μm. With other conditions being kept same, chloride molten salt is more propitious to the formation of PMN- PT solid solutions, and improving the compositional homogeneity of PMN-PT powders.

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Dissertationen zum Thema "Synthesis in molten salts"

Bao, Ke. „Low temperature synthesis of boron-based materials in molten salts“. Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/30134.

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Compared with conventional synthesis techniques, the so-called molten salt synthesis (MSS) technique has attracted substantial interest and has been used extensively to synthesise a range of advanced materials because it offers several advantages: (1) the synthesis reaction can be completed at a relatively low temperature and within a short time; (2) the resultant product powders are generally well dispersed and have high surface reactivity; (3) the grain shapes (spheroidal, platelet-shaped or rod-like) and sizes (nanoscale to microscale) can be controlled; and (4) the process is easy to perform, scalable and cost effective. In this thesis, a molten-salt-mediated magnesiothermic reduction technique was used to synthesise high-quality boron-based fine powders, including titanium diboride (TiB2), hafnium diboride (HfB2), lanthanum hexaboride (LaB6), calcium hexaboride (CaB6), amorphous boron and alumina-titanium diboride (Al2O3-TiB2) nanocomposites, at relatively low temperatures, from relatively cheap oxide-based raw materials. The effects of the processing parameters, such as salt type, starting batch composition, and firing temperature and time, on the reaction extents were investigated, based on which, the synthesis conditions optimised and the responsible underlying mechanisms proposed. Among the three chloride salts (NaCl, KCl and MgCl2), MgCl2 showed the best accelerating effect on the MSS of amorphous boron, TiB2, HfB2 and LaB6.This finding could be explained by the higher solubility levels of Mg and MgO in molten MgCl2 than in the other two salts. When using appropriately excessive amounts of Mg and/or B2O3 to compensate for their evaporation losses at reaction temperatures, phase-pure TiB2, HfB2 and LaB6 fine powders of 100-200 nm were synthesised after 4-6 h firing in MgCl2 at 900-1000°C. In the MSS of amorphous boron, 15 mol% excessive Mg was used. High-purity amorphous boron fine powders with sizes of 100-200 nm were achieved after 6 h firing in MgCl2 at 900°C and further leaching with hot H2SO4 solution. In the MSS of CaB6, CaCl2 facilitated the overall synthesis more effectively than NaCl, KCl or MgCl2. Upon using 20 mol% excessive Mg, phase-pure CaB6 nanoparticles of ~50 nm were formed in CaCl2 after 6 h at 800°C. Unlike in the molten-salt-mediated magnesiothermic reduction technique, Al2O3-TiB2 nanocomposite powders were synthesised via the aluminothermic reduction in molten salt. In this case, NaCl was regarded as the most appropriate reaction medium. When using appropriately excessive amounts of Al and B2O3, phase-pure Al2O3-TiB2 nanocomposite powders were synthesised after 4 h at 1150°C or 5 h at 1050°C. These synthesis conditions were much milder than those required by many other techniques reported previously. The “dissolution-precipitation” mechanism was found to be more dominant in the overall MSS processes than the “template-growth” mechanism. The success of this work indicates that the MSS technique could be a promising alternative approach to low-temperature synthesis of a range of nanomaterials. In addition, the MSS route opens new possibilities for the synthesis of known materials as well as new materials with complex structures, such as new zeolitic materials, metal organic frameworks and polymer chemistry by utilising tailored salt systems.

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Khangkhamano, Matthana. „Novel molten salt synthesis of ZrB2 and ZrC powders and molten salt synthesis of novel TiC“. Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/16562.

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Pure submicron-sized zirconium diboride (ZrB2) powder was synthesised via a molten salt mediated reduction route using ZrO2, Na2B4O7, and Mg powders as the starting raw materials and MgCl2 as the reaction medium. By using appropriately excessive amounts of Mg and Na2B4O7 to compensate for their evaporation losses, ZrO2 can be completely converted into ZrB2 after 3 h of firing at 1200 °C. This synthesis temperature is 100-500 °C lower than that of other conventional synthesis techniques. In addition, the formation of undesirable Mg3B2O6 can be effectively suppressed. To a large extent, the prepared ZrB2 particles preserved the shapes and sizes of the original ZrO2 particles, indicating a template growth mechanism for their formation in which ZrO2 functions as the reaction template. Using this developed synthesis method, submicron-sized and nanosized zirconium carbide (ZrC) powders were synthesised in the reaction system of ZrO2-Mg-carbon black using NaCl-KCl as the reaction medium. The synthesis temperatures were 950 and 850 °C for the former and the latter powder size, respectively, which are much lower temperatures than those used in most of the reported methods. Compared with the submicron-sized ZrO2 powders, the finer ZrO2 particles considerably enhanced the reaction rate and thus the completion of the reaction at a lower temperature. The resulting ZrC particles exhibited two different morphologies: one retained the shapes and sizes of the original ZrO2, and the other retained those of the starting carbon black, suggesting that both ZrO2 and carbon black had acted as reaction templates. In addition, the 2D-nanostructure of a non-layered structure material, titanium carbide (TiC), was fabricated. The novel TiC nanosheets (TNS) and TiC-coated graphite nanosheets (TCNS) were produced at 950 °C for 8 h and 900 °C for 5 h, respectively, in KCl molten salt using graphite nanosheets (GNS) as both a carbon source and reaction templates. The produced TNS and TCNS retained the shapes, sizes and thickness of the original GNS to a high degree, indicating that the GNS had acted as the reaction template. For TCNS, a lower molar ratio of Ti/C required a lower synthesis temperature and/or a shorter holding time. This effective processing technique was also employed to produce TiC foams at 1050 °C for 4 h using carbon foam as the reaction template. This synthesis temperature is significantly lower than that (>1450 °C) used in most of the other techniques. The resultant pores were clear of any undesired phases such as impurities and/or membranes, and the cell-networks were free of surface cracks and holes. The cell-networks, pore sizes, and cell sizes of the synthesised foams were well defined by those of the original carbon foam, suggesting a template growth mechanism of the formation of the TiC foam.

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Chung, In. „Exploratory synthesis in molten salts characterization, nonlinear optical and phase-change properties of new chalcophosphate compounds /“. Diss., Connect to online resource - MSU authorized users, 2008.

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Song, Yang. „Design of metal silicide nanoparticles in molten salts : electrocatalytic and magnetic properties“. Electronic Thesis or Diss., Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS498.pdf.

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Les siliciures de métaux de transition sont une famille de composés intermétalliques, qui ont été largement étudiés en tant que matériaux fonctionnels dans les circuits intégrés, la thermoélectricité, la supraconductivité, le magnétisme et la catalyse hétérogène. La nanostructuration offre la possibilité repousser les frontières de la science de ces matériaux avec de nouvelles phases et des propriétés diverses. Cependant, l'énergie de liaison relativement élevée des siliciures de métaux de transition nécessite généralement une température élevée pour leur formation, ce qui n'est pas propice à la conception de nanomatériaux et n'est pas compatible avec les méthodes de synthèse colloïdales traditionnelles. Dans cette thèse, des synthèses en sels fondus basées sur l'insertion d'éléments dans des nanoparticules sont développées. Des nanoparticules de siliciure de métal de transition (M-Si, M=Ni, Fe, NiFe, Co) et un silicophosphure de nickel ternaire sont cristallisés dans des solvants inorganiques à haute température, où un environnement dilué et sans carbone est fourni. Les nanoparticules de siliciures obtenues sont étudiées en électrocatalyse de l'oxydation de l'eau alcaline et du magnétisme. Les siliciures de NiFe démontrent une activité et une stabilité exceptionnelles résultant d'une structure originale cœur-coquille-coquille générée in situ, tandis que les nanoparticules de CoSi riches en défauts présentent un ferromagnétisme inhabituel. De plus, l'étude des nanoparticules de silicophosphure donne un aperçu de la conception de matériaux multinaires dans les sels fondus et du rôle des éléments non métalliques dans l’électrocatalyse de l’électrolyse de l’eau
Transition metal silicides are a family of intermetallic compounds, which have been widely studied as functional materials in integrated circuits, thermoelectricity, superconductivity, magnetism and heterogeneous catalysis. Nanostructuration offers the opportunity to extend the frontier of silicon-based materials science with novel phases and diverse properties. However, building transition metal silicides encompassing relatively high energy bonds usually requires high temperatures, which are not conducive for nanomaterial design and not compatible with the traditional colloidal synthesis methods. In this thesis, molten salts syntheses based on element insertion into nanoparticles are developed. Transition metal silicide nanoparticles (M-Si, M=Ni, Fe, NiFe, Co) and a ternary nickel silicophosphide are crystallized in high temperature inorganic solvents, where a diluted and carbon-free environment is provided. The obtained silicide nanoparticles are investigated in electrocatalysis of alkaline water oxidation and magnetism. NiFe silicides demonstrate outstanding activity and stability arising from an original in situ generated core-shell-shell structure, while defect-rich CoSi nanoparticles show an unusual surface related ferromagnetism. Moreover, the study of silicophosphide nanoparticles provides an insight in multinary material design in molten salts and the role of nonmetal elements in overall alkaline water splitting electrocatalysis

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Du, Yuansheng. „Synthesis of ceramic powders by a molten salt method“. Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/7411.

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Xie, Wei. „Molten salt synthesis and characterisation of novel carbide materials“. Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.544179.

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Murakami, Tsuyoshi. „Electrochemical reactions in molten salts for new energy conversion systems : novel ammonia synthesis processes and MH-type thermogalvanic cells“. Kyoto University, 2005. http://hdl.handle.net/2433/144687.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(エネルギー科学)
甲第11699号
エネ博第115号
新制||エネ||29(附属図書館)
23342
UT51-2005-D448
京都大学大学院ｴﾈﾙｷﾞｰ科学研究科ｴﾈﾙｷﾞｰ基礎科学専攻
(主査)教授尾形幸生, 教授片桐晃, 助教授萩原理加
学位規則第4条第1項該当

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Rørvik, Per Martin. „Synthesis of ferroelectric nanostructures“. Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5136.

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The increasing miniaturization of electric and mechanical components makes the synthesis and assembly of nanoscale structures an important step in modern technology. Functional materials, such as the ferroelectric perovskites, are vital to the integration and utility value of nanotechnology in the future. In the present work, chemical methods to synthesize one-dimensional (1D) nanostructures of ferroelectric perovskites have been studied. To successfully and controllably make 1D nanostructures by chemical methods it is very important to understand the growth mechanism of these nanostructures, in order to design the structures for use in various applications. For the integration of 1D nanostructures into devices it is also very important to be able to make arrays and large-area designed structures from the building blocks that single nanostructures constitute. As functional materials, it is of course also vital to study the properties of the nanostructures. The characterization of properties of single nanostructures is challenging, but essential to the use of such structures. The aim of this work has been to synthesize high quality single-crystalline 1D nanostructures of ferroelectric perovskites with emphasis on PbTiO3 , to make arrays or hierarchical nanostructures of 1D nanostructures on substrates, to understand the growth mechanisms of the 1D nanostructures, and to investigate the ferroelectric and piezoelectric properties of the 1D nanostructures. In Paper I, a molten salt synthesis route, previously reported to yield BaTiO3 , PbTiO3 and Na2Ti6O13 nanorods, was re-examined in order to elucidate the role of volatile chlorides. A precursor mixture containing barium (or lead) and titaniumwas annealed in the presence of NaCl at 760 °C or 820 °C. The main products were respectively isometric nanocrystalline BaTiO3 and PbTiO3. Nanorods were also detected, but electron diffraction revealed that the composition of the nanorods was respectively BaTi2O5/BaTi5O11 and Na2Ti6O13 for the two different systems, in contradiction to the previous studies. It was shown that NaCl reacted with BaO(PbO) resulting in loss of volatile BaCl2 (PbCl2 ) and formation and preferential growth of titanium oxide-rich nanorods instead of the target phase BaTiO3 (or PbTiO3 ). The molten salt synthesis route may therefore not necessarily yield nanorods of the target ternary oxide as reported previously. In addition, the importance of NaCl(g) for the growth of nanorods below the melting point of NaCl was demonstrated in a special experimental setup, where NaCl and the precursors were physically separated. In Paper II and III, a hydrothermal synthesis method to grow arrays and hierarchical nanostructures of PbTiO3 nanorods and platelets on substrates is presented. Hydrothermal treatment of an amorphous PbTiO3 precursor in the presence of a surfactant and PbTiO3 or SrTiO3 substrates resulted in the growth of PbTiO3 nanorods and platelets aligned in the crystallographic <100> orientations of the SrTiO3 substrates. PbTiO3 nanorods oriented perpendicular to the substrate surface could also be grown directly on the substrate by a modified synthesis method. The hydrothermal method described in Paper II and III was developed on the basis of the method described in Appendices I and II. In Paper IV, a template-assisted method to make PbTiO3 nanotubes is presented. An equimolar Pb-Ti sol was dropped onto porous alumina membranes and penetrated into the channels of the template. Single-phase PbTiO3 perovskite nanotubes were obtained by annealing at 700 °C for 6 h. The nanotubes haddiameters of 200 - 400 nm with a wall thickness of approximately 20 nm. Excess PbO or annealing in a Pb-containing atmosphere was not necessary in order to achieve single phase PbTiO3 nanotubes. The influence of the heating procedure and the sol concentration is discussed. In Paper V, a piezoresponse force microscopy study of single PbTiO3 nanorods is presented. The piezoelectric properties were studied in both vertical and lateral mode. Piezoelectric activity and polarization switching was observed in the vertical mode, demonstrating the ferroelectric nature of the nanorods. The nanorods decomposed after repeated cycling of the dc bias at one spot on the nanorod, which resulted in parts of the nanorod disappearing and/or accumulation of particles on the surface of the nanorod. In Paper VI, a method to contact single nanorods by electron beam induced deposition of platinum is presented. An organometallic compound, (trimethyl)-methylcyclopentadienylplatinum(IV), was used as precursor. A home-made apparatus was constructed for the purpose and was mounted onto a scanning electron microscope. Calculations based on apparatus geometry and molecular flow were used to estimate the deposition time and the height of the deposits. The location and height of the deposits were controlled so that single nanorods could be successfully contacted at the ends of the nanorods. Fabrication of a sample device for piezoresponse force microscopy studies of single nanorods using an axial dc bias setup is described in Appendix IV. A proposed experimental setup for such studies is also presented.

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Igoa, Saldaña Fernando. „Templated syntheses towards new boron-based nanomaterials“. Electronic Thesis or Diss., Sorbonne université, 2022. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2022SORUS459.pdf.

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Les composés contenant du bore présentent plusieurs propriétés physiques exploitables pour les besoins industriels actuels, à savoir l'activité catalytique, le magnétisme, la supercapacité, la capacité de stockage élevée du Li+ et d'excellentes propriétés mécaniques. La plupart de ces propriétés peuvent être adaptées et idéalement optimisées en façonnant le matériau en morphologies nanostructurées. Cependant, la nature fortement covalente des liaisons chimique impliquant le bore entrave la synthèse des nanostructures, car un apport d'énergie élevé est nécessaire pour former ces liaisons. Cela se traduit par des températures de synthèse élevées qui, en fin de compte, déclenchent également la croissance des grains. La synthèse de sels fondus a suscité un intérêt considérable en tant qu'outil de synthèse pour produire des nanostructures. Les sels fondus permettent d'effectuer des réactions chimiques dans un milieu liquide à des températures suffisamment élevées pour déclencher la cristallisation des borures, mais suffisamment douces pour limiter leur croissance. Malgré son succès, le contrôle de la morphologie du produit reste un défi important. Dans certains cas, ce problème peut être surmonté par des méthodes isomorphes, c'est-à-dire en utilisant des nanoparticules comme précurseurs, qui subissent une restructuration interne, de sorte qu'elles puissent également servir de nano-gabarits. Dans ce travail de thèse, l'utilisation de nano-gabarits couplée à la synthèse de nanomatériaux par sels fondus a été explorée pour deux systèmes difficiles à base de bore. Tout d'abord, des nanoparticles de carbure de bore ont été synthétisées à partir de gabarits de carbaborure de sodium, eux-mêmes synthétisés dans des sels fondus. L'intérêt de produire des nanostructures de carbure de bore a été largement reconnu dans la littérature comme un moyen d'améliorer sa dureté et son utilisation durable en tant que matériau de structure. La synthèse du gabarit a été réalisée grâce à la réaction entre une source de carbone polymère (polyéthylène) et NaBH4 dans du NaI fondu, ce qui a fourni des nanoparticules de ~ 5 nm. Ces nanoparticules ont alors pu être transformées avec succès en carbure de bore par décomposition thermique tout en conservant la morphologie nanométrique . En outre, la transformation du carbure de bore en monolithes denses a également été étudiée au moyen du frittage par plasma en courant pulsé. Une fois la densification et la consolidation réalisées, les propriétés mécaniques des nanostructures de carbure de bore ont été étudiées. Nous avons ainsi mis en évidence une dureté et une résistance à l'amorphisation significativement supérieures à celles de leur homologue massif. En parallèle, un système de borure métallique lamellaire a également été étudié avec des procédures analogues. Le système en question est Fe2AlB2, constitué de couches de Fe2B2 intercalées par des couches d'Al. Cette phase suscite un énorme intérêt en tant que précurseur possible vers le Fe2B2 bidimensionnel. La synthèse du Fe2AlB2 présente cependant plusieurs difficultés. Nous avons ici exploité l'approche du gabarit dans les sels fondus à partir d'un précurseur de FeB. Nous avons démontré que l'insertion d'Al en milieu LiCl/KCl fondu fourni bien Fe2AlB2. La délamination de la phase Fe2AlB2 vers 2D-Fe2B2 a été étudiée par oxydation sélective des atomes d'Al. Bien que la délamination n'ait pas été atteinte, nous avons mis en évidence un comportement thermique anormal dans Fe2AlB2. Lorsqu'il est traité thermiquement, Fe2AlB2 expulse des atomes de Fe et de B de la structure, générant ainsi des lacunes. Ce mécanisme a été démontré par diffraction des rayons X in situ et par des analyses post mortem
Boron-containing compounds exhibit several physical properties exploitable for current industrial needs, i.e. catalytic activity, magnetism, supercapacitance, high Li+ storage capacity and excellent mechanical properties. Most of these properties can be tailored and ideally optimized by shaping the material into nanostructured morphologies. However, the strong covalent nature of boron bonding hurdles the synthesis of nanostructures, as high input energy is needed to form such bonds. This translates in elevated synthesis temperatures, which ultimately also trigger grain growth. Molten-salts synthesis has gained considerable attention as a synthetic tool to yield nanostructures. Molten-salts permit to perform chemical reactions under a liquid media in a range of temperatures sufficiently large to trigger borides crystallization, but soft enough to limit their growth. Despite its success, the control over the product’s morphology remains a significant challenge. In some cases, this can be overcome by isomorphic methods, i.e., using nanoparticles as precursors, which undergo internal restructuration, so that they could also act as nanotemplates. In this thesis work, the use of nanotemplates coupled to molten salts synthesis of nanomaterials has been explored for two challenging boron-based systems. Firstly, boron carbide nanostructures were synthesized from sodium carbaboride templates, themselves synthesized in molten salts. The interest behind producing boron carbide nanostructures has been largely recognized in the literature, as a way to ameliorate its hardness and durable use as a structural material. The template synthesis is achieved thanks to the reaction between a polymeric carbon source (polyethylene) and NaBH4 in molten NaI, which yield ~ 5 nm nanoparticles. These nanoparticles can be successfully transformed to boron carbide while maintaining the nanoscale morphology by thermal decomposition. Furthermore, the processing of boron carbide into dense monoliths was also studied by means of spark-plasma sintering. Once proper densification and consolidation were achieved, the mechanical properties of the boron carbide nanostructures were investigated. We then highlighted a significantly higher hardness and amorphization resistance than the bulk counterpart. In parallel, a layered metal boride system has also been investigated with analogous procedures. The system in question is Fe2AlB2, consisting of Fe2B2 layers intercalated by Al layers. This phase has raised enormous interest as a possible parent phase towards bidimensional Fe2B2. The synthesis of Fe2AlB2 presents several difficulties though. We have herein exploited the templating approach in molten salts from a bulk FeB template, which we demonstrate that upon Al insertion in molten LiCl/KCl yields Fe2AlB2. The Fe2AlB2 phase delamination towards 2D-Fe2B2 was investigated by selective oxidation of the Al atoms. Although delamination did not occur, we evidenced an abnormal thermal behaviour in Fe2AlB2. When thermally treated, Fe2AlB2 expulses Fe and B atoms out of the structure, generating vacancies. This mechanism was demonstrated by in situ X-ray diffraction and post mortem analyses

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Rolland, Dalon Edouard de. „Borides and borophosphides at the nanoscale : liquid-phase synthesis and electrocatalytic water splitting properties“. Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS261.

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Les borures et phosphures de métaux de transition présentent des propriétés intéressantes en électrocatalyse pour la production de dihydrogène. Dans ces matériaux, l’élément du bloc p modifie la densité électronique des atomes métalliques, ce qui rend non seulement ces matériaux résistants à l’oxydation et à la corrosion, mais modifie aussi les propriétés catalytiques. Le développement de catalyseurs requiert la conception d’objets de rapport surface/volume élevé, donc à l’échelle nanométrique. Il est alors essentiel de développer des voies de synthèse adaptées à l’obtention de ces matériaux et à la recherche de nouveaux composés. Notamment la combinaison du bore avec du phosphore et/ou un ou plusieurs métaux de transition au sein d'un même composé pourrait engendrer des modifications profondes, notamment de la densité électronique des sites métalliques et de la géométrie des sites de surface en raison de la formation de structures cristallines spécifiques, contraintes par la présence de liaisons covalentes. Au vu des propriétés des phases binaires, l’ensemble des modifications en termes de morphologie, géométrie et composition permet d’envisager un contrôle de la réactivité et des propriétés (électro)catalytiques. Ce travail de thèse a ainsi porté sur le développement de borures et borophosphures de métaux de transition avec pour objectifs un contrôle morphologique à l'échelle nanométrique, le développement de nouveaux composés, y compris métastables, et la caractérisation de leurs propriétés électrocatalytiques. Les approches de synthèse choisies reposent sur deux piliers. D’abord les sels fondus, qui permettent de réaliser des synthèses à l'état liquide et à des températures intermédiaires entre celles de la chimie du solide et celles des voies colloïdales. Ainsi, les milieux réactionnels sont homogènes, permettent une réactivité accrue entre précurseurs solubles ou dispersés, et limitent la coalescence des particules. L’autre pilier est l'utilisation de nanoparticules métalliques comme nanoréacteurs dans lesquels le bore et/ou le phosphore sont incorporés, de façon à maintenir la morphologie des particules. Nous obtenons ainsi des nanomatériaux de phases pures dans le cas des borures de nickel et de fer, avec un contrôle de la composition et de la morphologie jamais obtenu auparavant. Ce contrôle n’a pu être atteint qu’en comprenant les mécanismes de formation des composés et nano-objets correspondant. Cette compréhension a pu être obtenue en développant le suivi in situ des synthèses grâce à la diffraction des rayons X sous rayonnement synchrotron. Nous avons ainsi pu mettre en évidence des intermédiaires réactionnels sous forme de nanoparticules amorphes, dont la nature a été élucidée grâce à la diffusion totale des rayons X couplée à la fonction de distribution de paires. Par extension, cette voie particulière de synthèse permet aussi la recherche de phases rares ou jamais reportées et pouvant présenter une importante activité électrocatalytique pour la dissociation de l'eau. Le choix des domaines de composition d'intérêt, guidé par l’apprentissage automatique pour la minimisation des énergies de formation, a ainsi permis de réaliser la synthèse de nanoparticules d’un borure bimétallique de nickel et cobalt bore. Nous avons aussi progressé dans l'étude de nouvelles voies de synthèse de phases ternaires borophosphures de nickel, rares et difficilement atteignables. Enfin, nous avons abordé l’exploration d'une voie de synthèse de nanoparticules métalliques exemptes de ligands organiques de surface, afin d'éviter des réactions secondaires ou des mécanismes compétitifs de diffusion au sein des métaux à partir des ligands, lors des synthèses en sels fondus. En nous basant sur des travaux démontrant la stabilité colloïdale de nanomatériaux dans des sels fondus, nous décrivons une méthode rapide et simple de synthèse de nanoparticules métalliques basés sur les sels fondus avec le nickel comme cas d'étude
Transition metal borides and phosphides present interesting properties in electrocatalysis for the production of dihydrogen. In these materials, the p-block element modifies the electron density of the metal atoms, which not only makes these materials resistant to oxidation and corrosion, but also modifies the catalytic properties. The development of catalysts requires the design of objects with a high surface/volume ratio, i.e. at the nanoscale. It is therefore essential to develop synthesis routes adapted to obtaining these materials and to the search for new compounds. In particular, combining boron with phosphorus and/or one or more transition metals in the same compound could lead to profound changes, notably in the electron density of the metal sites and the geometry of surface sites, due to the formation of specific crystalline structures constrained by the presence of covalent bonds. In view of the properties of the binary phases, all the modifications in terms of morphology, geometry and composition make it possible to control the reactivity and (electro)catalytic properties. This thesis work focused on the development of transition metal borides and borophosphides, with the objectives of morphological control on the nanometric scale, the development of new compounds, including metastable ones, and the characterisation of their electrocatalytic properties. The synthesis approaches chosen are based on two pillars. Firstly, molten salts, which enable synthesis to be carried out in the liquid state and at temperatures intermediate between those of solid-state chemistry and those of colloidal routes. Thus, the reaction media are homogeneous, enabling greater reactivity between soluble or dispersed precursors, and limiting the coalescence of particles. The other pillar is the use of metallic nanoparticles as nanoreactors in which boron and/or phosphorus are incorporated, so as to maintain the morphology of the particles. In this way, we obtain pure-phase nanomaterials in the case of nickel and iron borides, with a degree of control over composition and morphology that has never been achieved before. This control could only be achieved by understanding the formation mechanisms of the corresponding compounds and nano-objects. This understanding was achieved by developing in situ monitoring of the syntheses using X-ray diffraction under synchrotron radiation. We were thus able to identify reaction intermediates in the form of amorphous nanoparticles, the nature of which was elucidated using total X-ray scattering coupled with the pair distribution function. By extension, this particular synthesis route also enables us to search for rare or never reported phases that may exhibit significant electrocatalytic activity for the dissociation of water. The choice of compositional domains of interest, guided by machine learning to minimise formation energies, led to the synthesis of nanoparticles of a bimetallic boride of nickel and cobalt boron. We have also made progress in studying new synthesis routes for nickel borophosphide ternary phases, which are rare and difficult to obtain. Finally, we explored a route for synthesising metal nanoparticles without organic surface ligands, in order to avoid secondary reactions or competitive diffusion mechanisms within the metals from the ligands during molten salt synthesis. Based on work demonstrating the colloidal stability of nanomaterials in molten salts, we describe a rapid and simple method for synthesising metal nanoparticles based on molten salts using nickel as a case study

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Bücher zum Thema "Synthesis in molten salts"

T, Tomkins R. P., Bansal Narottam P, International Union of Pure and Applied Chemistry. und International Union of Pure and Applied Chemistry. Commission on Solubility Data., Hrsg. Gases in molten salts. Oxford: Pergamon, 1991.

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Tomkins, R. P. T. 1938- und Bansal Narottam P, Hrsg. Gases in molten salts. Oxford: Pergamon, 1991.

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Kerridge, David H., und Evgeny G. Polyakov, Hrsg. Refractory Metals in Molten Salts. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-015-9135-5.

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Gaune-Escard, Marcelle, und Kenneth R. Seddon, Hrsg. Molten Salts and Ionic Liquids. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2010. http://dx.doi.org/10.1002/9780470947777.

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Gaune-Escard, Marcelle, und Geir Martin Haarberg, Hrsg. Molten Salts Chemistry and Technology. Chichester, UK: John Wiley & Sons, Ltd, 2014. http://dx.doi.org/10.1002/9781118448847.

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Gaune-Escard, Marcelle, Hrsg. Molten Salts: From Fundamentals to Applications. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0458-9.

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NATO Advanced Study Institute on Molten Salts: from Fundamentals to Applications (2001 Kaş, Antalya İli, Turkey). Molten salts: From fundamentals to applications. Dordrecht: Kluwer Academic, 2002.

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N, Lee Kang, Yoshio Tetsuo und United States. National Aeronautics and Space Administration., Hrsg. Corrosion of mullite by molten salts. [Washington, D.C: National Aeronautics and Space Administration, 1996.

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C, Sequeira C. A., Hrsg. High temperature corrosion in Molten Salts. Uetikon-Zürich: Trans Tech Publications LTD, 2003.

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Buchteile zum Thema "Synthesis in molten salts"

Dolmatov, V. S., S. A. Kuznetsov, E. V. Rebrov und J. C. Schouten. „Electrochemical Synthesis of Double Molybdenum Carbides“. In Molten Salts Chemistry and Technology, 329–37. Chichester, UK: John Wiley & Sons, Ltd, 2014. http://dx.doi.org/10.1002/9781118448847.ch4k.

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Zhang, Shaowei, D. D. Jayaseelan, Zushu Li und William Edward Lee. „Molten Salt Synthesis of Ceramic Materials“. In Molten Salts and Ionic Liquids, 397–406. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9780470947777.ch25.

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Li, Zushu, Shaowei Zhang und William Edward Lee. „Molten Salt Synthesis of LaA1O3 Powder at Low Temperatures“. In Molten Salts and Ionic Liquids, 219–28. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9780470947777.ch16.

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Smith, P. J., A. Sethi und T. Welton. „Synthesis and Catalysis in Room-Temperature Ionic Liquids“. In Molten Salts: From Fundamentals to Applications, 345–55. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0458-9_14.

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Shurov, N. I., A. I. Anfinogenov, V. V. Chebykin, L. P. Klevtsov und E. G. Kazanskii. „The Synthesis of Borides, Carbides and Silicides of Refractory Metals in Ionic-Electronic Melts“. In Refractory Metals in Molten Salts, 81–86. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-015-9135-5_8.

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Tasaka, A., K. Ikeda, N. Osawa, M. Saito, M. Uno Y. Nishki, T. Furuta und M. Inaba. „Electrolytic Synthesis of (CF3)3N from a Room Temperature Molten Salt of (CH3)3N·mHF with BDD Electrode“. In Molten Salts Chemistry and Technology, 351–58. Chichester, UK: John Wiley & Sons, Ltd, 2014. http://dx.doi.org/10.1002/9781118448847.ch5b.

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Devyatkin, S. V., G. Kaptay, V. I. Shapoval, I. V. Zarutskii, V. P. Lugovoi und S. A. Kuznetsov. „Deposition of Titanium, Zirconium and Hafnium Diboride Coatings by High-Temperature Electrochemical Synthesis from Chloro-Fluoride Melts“. In Refractory Metals in Molten Salts, 73–80. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-015-9135-5_7.

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Zhao, Shi Xi, Qiang Li, Feng Bing Song, Chun Hong Li und De Zhong Shen. „Molten Salts Synthesis of Relaxor Ferroelectrics PMN-PT Powders“. In Key Engineering Materials, 10–13. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-410-3.10.

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Yang, Rui Song, Li Shan Cui, Yan Jun Zheng und Jin Long Zhao. „Synthesis of TiNi Particles in High Temperature Molten Salts“. In Materials Science Forum, 1941–44. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-960-1.1941.

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Zhao, Shi Xi, Qiang Li und Feng Bing Song. „Molten Salts Synthesis and Dielectric Properties of PMN-PT Ceramics“. In Materials Science Forum, 1153–56. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-960-1.1153.

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Konferenzberichte zum Thema "Synthesis in molten salts"

Hathaway, Brandon J., Masanori Honda und Jane H. Davidson. „Improved Switchgrass Gasification Using Molten Carbonate Salts“. In ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/es2011-54327.

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The use of concentrated solar energy for gasification of biomass is an efficient means for production of hydrogen rich synthesis gas. Utilizing molten alkali-carbonate salts as a reaction and heat transfer medium offers enhanced heat transfer, faster kinetics, and stability for solar transients. The effect of the molten salts on gasification of switchgrass is examined in terms of the reaction rates and product composition. Experiments were carried out in an electrically heated molten salt reactor. Switchgrass was gasified with steam at 1200 K in an inert gas and with salt. Reactivity indexes were calculated from measured gas production rates. Product composition was established via mass spectrometry. In salt, the total useful syngas production increased by 30% while reducing net carbon dioxide production. Reactivity increased 81%. Secondary products, in the form of condensable tar and unreacted char, were reduced by 77%.

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Imai, Yoshinori, Masatsune Kato, Takashi Noji und Yoji Koike. „Electrochemical Synthesis of the Perovskite Ba1 xCsxBiO3 from Molten Salts“. In LOW TEMPERATURE PHYSICS: 24th International Conference on Low Temperature Physics - LT24. AIP, 2006. http://dx.doi.org/10.1063/1.2354887.

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El Far, Baha, Syed Muhammad Mujtaba Rizvi, Yousof Nayfeh und Donghyun Shin. „Effect of Synthesis Protocol in Enhancing Heat Capacity of Molten Salt Nanofluids“. In ASME 2020 14th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/es2020-1709.

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Abstract Concentrated solar power (CSP) incorporated with thermal energy storage (TES) is an appealing solar energy generation technology. TES stores heat during the daytime and releases it in the nighttime. As a result, CSP can produce continuously even at night. Storing heat by TES makes CSP a unique technology among various renewable energy sources which often suffer from the intermittency of energy supply (e.g., wind turbines without wind, photovoltaics at night, etc.). The energy conversion efficiency of CSP is directly related to the properties of the TES medium. Binary or ternary mixtures of molten salts (Solar Salt) are commonly used as the TES in CSP due to its high-temperature stability. Enhancing the thermophysical properties of the molten salt medium can significantly improve TES performance. Various studies have reported the anomalous specific heat enhancement of molten salt-based nanofluids. However, the underlying mechanism for this enhancement was yet discovered. In this study, the effect of different synthesis conditions on the resultant specific heat capacity of molten salt-based nanofluids was investigated. Several molten salt nanofluids (NaNO3–KNO3 with SiO nanoparticles at 1 wt. % concentration) were prepared at different thermal cycling conditions and their thermal performance was characterized by a differential scanning calorimeter (DSC).

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Jo, Byeongnam, und Debjyoti Banerjee. „Enhanced Specific Heat Capacity of Molten Salts Using Organic Nanoparticles“. In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64001.

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In this study we explore the material properties of carbonate salt eutectics that melt at high temperatures (exceeding 480 °C). These salt eutectics demonstrated anomalous enhancement in the specific heat capacity in both solid and liquid phases — when mixed with carious organic nanoparticles such as carbon nanotubes (CNT) and graphite nanoparticles. Theses experimental measurements are compared with previous reports in the literature for exploring the effect of the synthesis protocol on the resulting thermo-physical properties of these nanomaterials. The enhancement of the thermo-physical properties on mixing with nanoparticles is of significant interest in reducing the cost of thermal energy storage (TES) devices and systems. TES can be utilized for levelizing peaks in cyclical energy demands (or duties) that is typical of renewable energy applications where the input energy source may be intermittent (e.g., solar thermal); as well as in geothermal and nuclear energy applications.

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Hathaway, Brandon J., Jane H. Davidson und David B. Kittelson. „Solar Gasification of Biomass: Kinetics of Pyrolysis and Steam Gasification in Molten Salt“. In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-39829.

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The use of concentrated solar energy for pyrolysis and gasification of biomass is an efficient means for production of hydrogen rich synthesis gas. Utilizing molten alkali-carbonate salts as a reaction and heat transfer media offers enhanced stability and higher reaction rates to these solar processes. To establish the reaction kinetics, experiments were carried out in an electrically heated molten salt reactor. Cellulose or activated charcoal were pyrolyzed or gasified with steam from 1124 K to 1235 K with and without salt. Arrhenius rate expressions are derived from the data supported by a numerical model of heat and mass transfer. The average rate of the reactions in molten salt, as measured by their reactivity index, is increased by 70% for pyrolysis and by an order of magnitude for steam gasification.

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Bradshaw, Robert W., und Nathan P. Siegel. „Molten Nitrate Salt Development for Thermal Energy Storage in Parabolic Trough Solar Power Systems“. In ASME 2008 2nd International Conference on Energy Sustainability collocated with the Heat Transfer, Fluids Engineering, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/es2008-54174.

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Thermal energy storage can enhance the utility of parabolic trough solar power plants by providing the ability to match electrical output to peak demand periods. An important component of thermal energy storage system optimization is selecting the working fluid used as the storage media and/or heat transfer fluid. Large quantities of the working fluid are required for power plants at the scale of 100-MW, so maximizing heat transfer fluid performance while minimizing material cost is important. This paper reports recent developments of multi-component molten salt formulations consisting of common alkali nitrate and alkaline earth nitrate salts that have advantageous properties for applications as heat transfer fluids in parabolic trough systems. A primary disadvantage of molten salt heat transfer fluids is relatively high freeze-onset temperature compared to organic heat transfer oil. Experimental results are reported for formulations of inorganic molten salt mixtures that display freeze-onset temperatures below 100°C. In addition to phase-change behavior, several properties of these molten salts that significantly affect their suitability as thermal energy storage fluids were evaluated, including chemical stability and viscosity. These alternative molten salts have demonstrated chemical stability in the presence of air up to approximately 500°C in laboratory testing and display chemical equilibrium behavior similar to Solar Salt. The capability to operate at temperatures up to 500°C may allow an increase in maximum temperature operating capability vs. organic fluids in existing trough systems and will enable increased power cycle efficiency. Experimental measurements of viscosity were performed from near the freeze-onset temperature to about 200°C. Viscosities can exceed 100 cP at the lowest temperature but are less than 10 cP in the primary temperature range at which the mixtures would be used in a thermal energy storage system. Quantitative cost figures of constituent salts and blends are not currently available, although, these molten salt mixtures are expected to be inexpensive compared to synthetic organic heat transfer fluids. Experiments are in progress to confirm that the corrosion behavior of readily available alloys is satisfactory for long-term use.

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Mortazavi, Farzam, und Debjyoti Banerjee. „Review of Molten Salt Nanofluids“. In ASME 2016 Heat Transfer Summer Conference collocated with the ASME 2016 Fluids Engineering Division Summer Meeting and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ht2016-7316.

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Literature review of molten salt nanofluids is performed in this study with focus on the thermo-fluidic properties and performance in thermal management applications. The colloidal mixture of nanoparticles in a base liquid phase is called nanofluid. Molten salts such as alkali nitrate eutectics, alkali carbonate eutectics and alkali chloride eutectics have high melting temperatures. These materials are suitable for various high temperature applications, including as Heat Transfer Fluid (HTF), Thermal Energy Storage (TES), Concentrated Solar Power (CSP) plants, nuclear power, etc. The major drawback of molten salt materials is their low thermal conductivity and specific heat capacity. Enhancing the thermo-physical properties of molten salt materials can lower the cost of power production involving these materials (e.g., as HTF and/ or TES in CSP or nuclear power plants. Mixing molten alt eutectics with nanoparticles (e.g., molten salt nanofluids) can provide a cost-effective technique for enhancing the specific heat capacity and thermal conductivity which in turn can enable the reduction in the cost of power production. In this review - the following topics involving molten salt nanofluids were explored: thermo-physical property measurements, numerical modeling (e.g., Molecular Dynamics/ MD simulations), materials characterization (e.g., using electron microscopy techniques — such as SEM and TEM). For example, SEM studies in conjunction with MD simulation results confirm the formation of a dense layer of fluid molecules on the surface of nanoparticles that can enhance the specific heat capacity of these molten salt nanomaterials. Subsequently the concepts of nanofins was explored (which involves the study of interfacial thermal impedance, such as resistance, capacitance and diodicity). The contribution of these interfacial thermal impedances to the enhancement of specific heat capacity and thermal conductivity are also explored. Specific heat enhancement as high as 100% has been observed for various molten salt eutectics when doped with 1.5% (weight) silica nanoparticles. Various synthesis protocols such as one-step, two-step and three-step methods as well as conventional experimental methods used for specific heat capacity measurement are compared and examined. A review of the effects of concentration, nanoparticle size, temperature, base fluid, and nanofluid chemical properties is also performed. Other topics of interest are the anomalous enhancement of thermal conductivity in molten salt nanofluids which contradict typical predictions obtained from using the effective medium theory. The available data in literature shows enhancement in thermal conductivity by as much as 35–45% for carbonate eutectics doped with silica nanoparticles at 1% mass fraction. The possible mechanisms suggested for this improvement are briefly discussed and compared with experimental observations (e.g., using SEM). In addition, nanofluids often display non-Newtonian rheological behavior. This necessitates a rigorous study, since the applications of nanofluids will impact the required pumping power. Studies show that the rheological properties of molten salt nanofluids are a function of base salt composition, shape of nanoparticles selected, chemical formula of nanoparticles, concentration of nanoparticles, size of nanoparticles, temperature, shear rate and synthesis protocol of the nanofluid. Several models are introduced to predict the viscosity variation along with their advantageous and disadvantages. SEM results show agglomeration of nanoparticles can be reduced by doping the nanofluids with very small values of mass fractions of additives such as Gum Arabic.

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Kolb, Gregory, Clifford Ho, Brian Iverson, Timothy Moss und Nathan Siegel. „Freeze-Thaw Tests on Trough Receivers Employing a Molten Salt Working Fluid“. In ASME 2010 4th International Conference on Energy Sustainability. ASMEDC, 2010. http://dx.doi.org/10.1115/es2010-90040.

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Several studies predict an economic benefit of using nitrate-based salts instead of the current synthetic oil within a solar parabolic trough field. However, the expected economic benefit can only be realized if the reliability and optical performance of the salt trough system is comparable to today’s oil trough. Of primary concern is whether a salt-freeze accident and subsequent thaw will lead to damage of the heat collection elements (HCEs). This topic was investigated by experiments and analytical analysis. Results to date suggest that damage will not occur if the HCEs are not completely filled with salt. However, if the HCE is completely filled at the time of the freeze, the subsequent thaw can lead to plastic deformation and significant bending of the absorber tube.

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Shin, Donghyun, und Debjyoti Banerjee. „Experimental Investigation of Molten Salt Nanofluid for Solar Thermal Energy Application“. In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44375.

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The overall efficiency of a Concentrated Solar Power (CSP) system is critically dependent on the thermo-physical properties of the Thermal Energy Storage (TES) components and the Heat Transfer Fluid (HTF). Higher operating temperatures in CSP result in enhanced thermal efficiency of the thermodynamic cycles that are used in harnessing solar energy (e.g., using Rankine cycle or Stirling cycle). Particlularly, high specific heat capacity (Cp) and high thermal conductivity (k) of the HTF and TES materials enable reduction in the size and overall cost of solar power systems. However, only a limited number of materials are compatible for the high operating temperature requirements (exceeding 400°C) envisioned for the next generation of CSP systems. Molten salts have a wide range of melting point (200°C∼500°C) and are thermally stable up to 700°C. However, thermal property values of the molten salts are typically quite low (Cp is typically less than ∼2J/g-K and k is typically less than ∼1 W/m-K). To obviate these issues the molten salts can be doped with nanoparticles — resulting in the synthesis / formation of nanomaterials (nanocomposites and nanofluids). Nanofluids are colloidal suspensions formed by doping with minute concentration of nanoparticles. Nanofluids were reported for anomalous enhancement in their thermal conductivity values. In this study, molten salt-based nanofluids were synthesized by liquid solution method. A differential scanning calorimeter (DSC) was used to measure the specific heat capacity values of the proposed nanofluids. The observed enhancement in specific heat is then compared with predictions from conventional thermodynamic models (e.g. thermal equilibrium model or “simple mixing rule”). Transmission Electron Microscopy (TEM) is used to verify that minimal aggregation of nanoparticles occurred before and after the thermocycling experiments. Thermocycling experiments were conducted for repeated measurements of the specific heat capacity by using multiple freeze-thaw cycles of the nanofluids/ nano-composites, respectively. This study demonstrates the feasibility for using novel nanomaterials as high temperature nanofluids for applications in enhancing the operational efficiencies as well as reducing the cost of electricity produced in solar thermal systems utilizing CSP in combination with TES.

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Palizdar, Meghdad, Timothy Comyn, Santosh Kulkarni, Lynette Keeney, Saibal Roy, Martyn Pemble, Roger Whatmore und Andrew Bell. „Synthesis of platelets Bi5Fe0.5Co0.5Ti3O15 via the molten salt method“. In European Conference on the Applications of Polar Dielectrics (ECAPD). IEEE, 2010. http://dx.doi.org/10.1109/isaf.2010.5712254.

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Berichte der Organisationen zum Thema "Synthesis in molten salts"

Williamson, Mark A., und James Willit. Synthesis of Molten Chloride Salt Fast Reactor Fuel Salt from Spent Nuclear Fuel. Office of Scientific and Technical Information (OSTI), Dezember 2019. http://dx.doi.org/10.2172/1581580.

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Chang, Do R. Microemulsion of Molten Salts. Fort Belvoir, VA: Defense Technical Information Center, Februar 1991. http://dx.doi.org/10.21236/ada233054.

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K. Butcher, D. Smith, C. L. Lin und L. Aubrey. Detection and removal of molten salts from molten aluminum alloys. Office of Scientific and Technical Information (OSTI), August 1999. http://dx.doi.org/10.2172/751037.

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Reavis, J. G. Experimental studies of actinides in molten salts. Office of Scientific and Technical Information (OSTI), Juni 1985. http://dx.doi.org/10.2172/5492312.

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Monreal, Marisa Jennifer, und Jay Matthew Jackson. Measuring the Properties of Actinide-Molten Salts. Office of Scientific and Technical Information (OSTI), Juni 2020. http://dx.doi.org/10.2172/1637688.

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Donahue, Francis M., Leif Simonsen, Russell Moy und Sara Mancini. Metal/Metallion System in Low Temperature Molten Salts. Fort Belvoir, VA: Defense Technical Information Center, März 1989. http://dx.doi.org/10.21236/ada208025.

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Pint, Bruce. Progression to Compatibility Evaluations in Flowing Molten Salts. Office of Scientific and Technical Information (OSTI), Juli 2020. http://dx.doi.org/10.2172/1649281.

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Rose, M., J. Krueger, T. Lichtenstein, E. Wu und L. Gardner. Precision of Property Measurements with Reference Molten Salts. Office of Scientific and Technical Information (OSTI), August 2021. http://dx.doi.org/10.2172/1823476.

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Haiges, Ralf, und Karl O. Christe. A New Synthesis of Anhydrous Cesium Salts. Fort Belvoir, VA: Defense Technical Information Center, Oktober 2001. http://dx.doi.org/10.21236/ada408096.

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Rodriguez, Salvador B. Advancing Molten Salts and Fuels at Sandia National Laboratories. Office of Scientific and Technical Information (OSTI), September 2017. http://dx.doi.org/10.2172/1398235.

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