Synthesis hydrothermal routes

An additional route consists of using the reconstruction ability of some LDH materials after a moderate thermal treatment. This is a pecuharity of LDH systems called the memory effect the LDH lamellar framework is reconstructed in the presence of the polymer with concomitant intercalation. Finally, a post-synthesis hydrothermal treatment can be applied in all cases, which may improve the inter- and intralamellar organization of the LDH/polymer nanocomposites. 

Ambient aqueous routes and hydrothermal routes The synthesis of rare earth orthophosphate NCs could be carried out in aqueous solutions by the precipitation of rare earth cations by phosphate anions, due to the low aqueous solubility of RPO4. A typical synthesis begins with soluble rare earth salts in aqueous solution, such as nitrates or chlorides, and a phosphate source like phosphate M H3 P04, triphosphate M5P3O10 (M = Na, K, or NH4), or PI3PO4. The two solutions are mixed at room temperature or elevated temperature to form gel-like precipitation as precursor. Then the mixture of precipitation and mother liquor is... 

In addition to the orthophosphates, other rare earth phosphates could also be obtained through hydrothermal routes. Tang et al. reported the synthesis of so-called CeP (with a composition of Ce(FIP04)2" H2O) nanotubes (Tang et al., 2005c). Concentrated phosphoric acid solution of 6 M was heated to a temperature ranging from 50 to 110 °C to form a condensed lirrear polyphosphate (P 03 +i) +2 Then, the (NH4)2Ce(N03)e solution is... 

A survey of recent literature on zeolite membrane preparation reveals that synthesis processes, even for well-known zeolite structures (i.e., MFl, LTA), are still carried out batchwise, using a hydrothermal route to produce a thin layer from hydrogels or sols containing the corresponding nutrients. As a general rule, the reactant mixture in contact with the support changes in composition with time provoking a reduction of the membrane quality. 

Another related group of compounds whose hydrothermal synthesis has been studied extensively is the garnets. These compounds have had a wide variety of optical and magnetic applications and are normally made from fluxes, but several hydrothermal routes have also been developed. A variety of garnets can be synthesized from aqueous base at temperatures above 400 °C [59,60]. 

The hydrothermal route has been used for synthesizing nanotubes and related structures of a variety of other inorganic materials as well. Thus, nanotubes of several metal oxides (eg., SiO, V2O5, ZnO ) have been produced hydrothermally. Nanotubes of oxides such as VJO, are also conveniently prepared from a suitable metal oxide precursor in the presence of an organic amine or a surfactant. Surfactant-assisted synthesis of CdSe and CdS nanotubes has been reported. Here the metal oxide reacts with the sulfidizing/selenidizing agent in the presence of a surfactant such as TritonX. ... 

K. Madhusudan Reddy, D. Guin, S.V. Manoramaa, A.R. Reddy, Selective synthesis of nanosized Ti02 by hydrothermal route Characterization, structure property relation and photochemical application . Journal of Materials Research, 19, 2567-2575, (2004). 

Chen H, Wang Y, Dong S. An effective hydrothermal route for the synthesis of multiple PDDA-protected noble-metal nanostructures. Inorganic Chem 2007 46(25) 10587-93. 

Razak et al. [84] prepared Ba Sri cTi03 nanoparticles using a hydrothermal route and discussed the effects of the Ba Sr ratio, (Ba+Sr) Ti02 ratio, and the reaction time on the resultant particles. In addition, Deshpande and Khollam [85] synthesized BaojsSro.asTiOa nanoparticles by a microwave-hydrothermal route with faster crystallization, shorter synthesis time, and higher purity compared with the conventional hydrothermal route. 

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. 

Fang LM, Zu XT, Li Zl, Zhu S, liu CM, Zhou WL, Wang LM (2008) Synthesis and characteristics of Fe3 -doped SnO nanoparticles via sol-gel-calcination or sol-gel-hydrothermal route. J Alloys Compd 454 261-267 Fleischer M, Hanrieder W, Meixner H (1990) Stability of semiconducting gaUium oxide thin films. Thin SoUd Films 190 93-102... 

Fig. 6.7 Schematic of the shape-controlled synthesis of ZnO nanorods via a microwave hydrothermal route [47]...

Synthesis may also be carried out at a lower pH using fluoride-containing media, wherein F ions are thought to act as structure directors via strong interactions with framework Si atoms. Consequently, the nucleation rate is decreased, which yields larger crystals relative to standard alkaline hydrothermal routes.The fluoride route under neutral/acidic pH conditions is also extremely useful to synthesize zeolite-like materials called zeotypes, which contain elements other than silicon and aluminum (e.g., titanosilicates, zirconosilicates, etc.). Under alkaline conditions, the precursors would be preferentially precipitated as hydroxide species rather than ordered arrays. 

Application of MWs has been proved extremely suitable in the field of wet-chemical nanoparticle synthesis particularly for pure metal NCs [205]. Unless few rare exceptions of MW-assisted syntheses of metal NCs set up in polar non-protic [206, 207] or wholly non-polar environment [208], most of the metal synthetic pathways presented in literature are based on hydrothermal routes namely polar and protic reaction media. In details these latter approaches found on hot reduction either of water-dispersed metal salts supported by the active presence of particle-stabilizing reductants, [209-212] or in alcoholic media operating as both... 

Annal-Therese, H., Li, J., Kolb, U. and Tremel, W., Facile laige scale synthesis of WS2 nanotubes from WC nanorods prepared by hydrothermal route. Solid State Sciences, 7 (1), 2005,67-72. 

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