Molten salt synthesis method

The relation between the drying method and the surface area of powders is important. There are many drying methods, such as air, vacuum, and freeze drying. This point is illustrated with the examples of (Bao.2Pbo.8)Ti03. In powder preparation, the surface reactivity, that is, the specific surface area, plays a very important role. Specific surface areas are often determined by the BET (Brunauer, Eminett, and Teller) method. Typical BET plots of the sol-gel, CMO (calcined mixed oxide method), and MSS (molten salt synthesis method) [15] derived powders are shown in Fig. 1. 

Bai, J.B. Hamon, A.L. Marraud, A. Jouffrey, B. Zymla, V. Synthesis of SWCNTs and MWCNTs by molten salt (NaCl) method. Chem. Phys. Lett. 2002, 365, 184-188. 

There are two other methods for producing ferrite powders that deserve attention molten-salt synthesis and shock-wave loading. In molten-salt synthesis, Fe203 and the corresponding carbonate, oxide, hydroxide or nitrate needed to produce the ferrite phase are dry blended with a mixture of NaCl and KCl. This reaction mixture, in a Pt crucible, is placed in a furnace at 800-1100 °C for lh the chloride solvent is melted and provides an efficient heating medium for the reaction. After cooling, the solvent is separated from the ferrite by dissolution in water. The product can be finally collected by filtration. Ba and Sr hexaferrite powders have been prepared by this method (Arendt, 1973). Submicron, high-quality crystallites with a low ferrous content were obtained. 

Many techniques have been developed for the synthesis of nanoparticles, such as solid-state reactions [5-14], molten salt synthesis [15-21], hydrothermal methods [22-29], sol-gel processing [30-36], co-precipitation [37-46], thermal evaporation [47-50], plasma methods [51-54], chemical vapor deposition [55-60], pulsed laser deposition [61-66], and magnetron sputtering [67-72],... 

Many routes for obtaining template particles are known using molten salt synthesis, hydrothermal synthesis, sol—gel processing, as well as hybrid, multistep methods. The TGG method has been widely used for the development and texturing of piezoelectric ceramics [44]. One of the reasons for this widespread use is the cost consideration, since TGG enables the relatively inexpensive fabrication of textured ceramics with single crystal-Uke properties. However, our present discussion pivots around the mechanical properties. 

Molten salt synthesis based on the use of salts with low melting point has been reported to be one of the simplest techniques for preparing ceramic materials [57]. Well-faced LNM crystals were synthesized by molten salt technology using stoichiometric amount of LiOH, Ni(OH)2, and y-MnOOH (2 1 3) calcined at 700-1000 °C [57]. Micro-sized LNM crystals in plate and octahedral shapes were synthesized by molten-salt method in LiCl and LiCl-KCl fluxes the main surface facets on the plates were determined to be (112) crystal planes [58]. Recenfly, microscale LNM was synthesized using nanothom stmctured MnOa mixed with Li and Ni precursors [59]. 

Besides wet-synthesis methods, another two novel methods have been used to synthesize MA spinel powders. These are mechanochemical alloying and molten salt synthesis (MSS). 

Titanium Silicides. The titanium—silicon system includes Ti Si, Ti Si, TiSi, and TiSi (154). Physical properties are summarized in Table 18. Direct synthesis by heating the elements in vacuo or in a protective atmosphere is possible. In the latter case, it is convenient to use titanium hydride instead of titanium metal. Other preparative methods include high temperature electrolysis of molten salt baths containing titanium dioxide and alkalifluorosiUcate (155) reaction of TiCl, SiCl, and H2 at ca 1150°C, using appropriate reactant quantities for both TiSi and TiSi2 (156) and, for Ti Si, reaction between titanium dioxide and calcium siUcide at ca 1200°C, followed by dissolution of excess lime and calcium siUcate in acetic acid. 

Over the past few years, a large number of experimental approaches have been successfully used as routes to synthesize nanorods or nanowires based on titania, such as combining sol-gel processing with electrophoretic deposition,152 spin-on process,153 sol-gel template method,154-157 metalorganic chemical vapor deposition,158-159 anodic oxidative hydrolysis,160 sonochemical synthesis,161 inverse microemulsion method,162 molten salt-assisted and pyrolysis routes163 and hydrothermal synthesis.163-171 We will discuss more in detail the latter preparation, because the advantage of this technique is that nanorods can be obtained in relatively large amounts. 

An unusual new synthesis method involves carrying out reactions in a molten salt medium, and has been used on an industrial scale for the production of metallic nitride, carbide or carbonitride powders.25 An illustration of this CEREX process is the preparation of oxygen-free titanium nitride in molten calcium chloride. The method involves the reaction between titanium tetrachloride and calcium nitride ... 

Molecular recognition, in Rh Cp complexes, 7, 155 Molecular weight, in alkene living polymerizations, 11, 715 Moller-Plesset calculations, as perturbation method, 1, 646 Molten salts, and ionic liquids, 1, 848 Molybdacarboranes, synthesis, 3, 216 Molybdenocene dichloride, bioorganometallic chemistry,... 

The flux method is a well-known method used for single crystal growth. It has not been applied to the synthesis of fine powders because usually high temperature heating is necessary to obtain molten salts. However, the modified flux method has been reported for the preparation of fine panicles of Ce,. Pr Oj solid solutions.In the preparation of the powders by the flux method, molten salts of alkali metal hydroxides, nitrates, and chlorides are used as solvents. The use of molten salts. 

The system CpeTiCle/AlClBu is an efficient reagent for hydroalumination of disubstituted acetylenes in a regio-and stereoselective method for the synthesis of -alkenylchloralanes.1169 The reduction carbonylation of Cp2TiCl2 at room temperature by chloroaluminate molten salts or ionic liquids has been reported.1170... 

In 1963 Dr. Danbk joined the Institute of Inorganic Chemistry of the Slovak Academy of Sciences in Bratislava, of which he was the director in the period 1991-1995. His main field of interest was the physical chemistry of molten salts systems in particular the study of the relations between the composition, properties, and structure of inorganic melts. He developed a method to measure the electrical conductivity of molten fluorides. He proposed the thermodynamic model of silicate melts and applied it to a number of two- and three-component silicate systems. He also developed the dissociation model of molten salts mixtures and applied it to different types of inorganic systems. More recently his work was in the field of chemical synthesis of double oxides from fused salts and the investigation of the physicochemical properties of molten systems of interest as electrolytes for the electrochemical deposition of metals from natural minerals, molybdenum, the synthesis of transition metal borides, and for aluminium production. 

Molten salts (called fluxes) and also water at high pressures and temperatures are excellent solvents for many inorganic solid compounds. Inorganic synthesis from flux is discussed in Section 8.3.2, while water as a solvent for synthesis of oxides under hydrothermal conditions is the subject of Section 8.3.3. Colloidal methods are of increasing importance and the synthesis of mixed oxides by polymerization of hydrolized metal-organic molecules is the fourth subject in the group of synthesis from liquids. 

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