Solvothermal synthesis

The preparation of ZnSe materials is an area of interest and study. The coordinating ability of the solvent used in the solvothermal synthesis of zinc selenide was demonstrated to play an important role in the nucleation and growth of nanocrystalline ZnSe.604 Thermolysis of bis [methyl( -hexyl)di-seleno]carbamato]zinc gave highly monodispersed particles characterized by electronic spectroscopy, photoluminescence, X-ray diffraction, and electron microscopy.605... 

Wu, H., et al., Solvothermal synthesis and optical limiting properties of carbon nanotube-based hybrids containing ternary chalcogenides. Carbon, 2012. 50(13) p. 4847-4855. 

Qian Y (1999) Solvothermal synthesis of III-V nanociystalline semiconductors. Adv Mater 11 1101-1102... 

It seems useful to understand the mechanisms involved in the chemistry and in the electrochemistry of sulfur and polysulfides. During the last 10 years, more than 90 papers deahng with solvothermal synthesis of chalcogenides MxE or binary chalcogenides MxM Ez (E = S, Se, or Te) have been published. In a typical process, a metal and/or a metallic salt is heated in a solvent (benzene, toluene, pyridine, ethylenediamine, water, etc.) at 100-200 ° C in the presence of an excess of chalcogen (see for instance Ref. 125). These empirical syntheses would benefit from a sound understanding of the involved mechanisms. 

Solvothermal Synthesis of Photocatalytic TiO Nanoparticles Capable of Killing Escherichia coli... 

A solvothermal process is one in which a material is either recrystallized or chemically synthesized from solution in a sealed container above ambient temperature and pressure. The recrystallization process was discussed in Section 1.5.1. In the present chapter we consider synthesis. The first solvothermal syntheses were carried out by Robert Wilhelm Bunsen (1811-1899) in 1839 at the University of Marburg. Bunsen grew barium carbonate and strontium carbonate at temperatures above 200°C and pressures above 100 bar (Laudise, 1987). In 1845, C. E. Shafhautl observed tiny quartz crystals upon transformation of freshly precipitated silicic acid in a Papin s digester or pressure cooker (Rabenau, 1985). Often, the name solvothermal is replaced with a term to more closely refer to the solvent used. For example, solvothermal becomes hydrothermal if an aqueous solution is used as the solvent, or ammothermal if ammonia is used. In extreme cases, solvothermal synthesis takes place at or over the supercritical point of the solvent. But in most cases, the pressures and temperatures are in the subcritical realm, where the physical properties of the solvent (e.g., density, viscosity, dielectric constant) can be controlled as a function of temperature and pressure. By far, most syntheses have taken place in the subcritical realm of water. Therefore, we focus our discussion of the materials synthesis on the hydrothermal process. 

The entire spectrum of tools in synthetic inorganic chemistry, including high temperature methods, precipitation, solvothermal synthesis, sol-gel chemistry, chemical vapor deposition (CVD), and soft matter techniques adopted in part from organo-metallic chemistry, have been applied to synthesize the active mass of catalysts. Table 4.2.1 summarizes basic techniques. The preparation methods differ whether... 

Solvothermal synthesis Kinetic control over the phases formed Predictions difficult... 

Nanocrystals are zero-dimensional particles and can be prepared by several chemical methods, typical of them being reduction of salts, solvothermal synthesis and the decomposition of molecular precursors, of which the first is the most common method used... 

Foster. P. M. Thomas, P. M, Cheetham, A. K. Biphasic Solvothermal Synthesis A New Approach for Hybrid Inorganic-Organic Materials, Chem. Mater. 2002, 14, 17-20. 

Kiebach et al. (2005) SEM Organogermanates Multiple kinetics of nucleation and growth + + n.a. Solvothermal synthesis... 

Intercalation. The final low-temperature method to be discussed is intercalation. This method could be viewed either as a post-synthetic modification of a material or a parallel event occurring during the synthesis of a material. The solvothermal synthesis of Cu2SbSe3(C2N2Hg) is a good example of the latter. In this section, however, the focus will be on the former. As a post-synthetic modification, intercalation can be used to chemically alter a material that has been produced using some other technique. 

Solvothermal method has been used in synthesis of a series of non-oxide nanomaterials, such as semiconductors [1,2], ceramic materials [3], and in fabricating special nanostructures [4]. It will be an exciting, promising field for designing and preparing advanced materials in the future. This paper focuses on some aspects of recent progress in solvothermal synthesis of non-oxides nanomaterials. 

We have developed solvothermal synthesis as an important method in research of metastable structures. In the benzene-thermal synthesis of nanocrystalline GaN at 280°C through the metathesis reaction of GaClj and U3N, the ultrahigh pressure rocksalt type GaN metastable phase, which was previously prepared at 37 GPa, was obtained at ambient condition [5]. Diamond crystallites were prepared from catalytic reduction of CCI4 by metallic sodium in an autoclave at 700°C (Fig.l) [6]. In our recent studies, diamond was also prepared via the solvothermal process. In the solvothermal catalytic metathesis reaction of carbides of transition metals and CX4 (X = F, Cl, Br) at 600-700°C, Raman spectrum of the prepared sample shows a sharp peak at 1330 cm" (Fig. 1), indicating existence of diamond. In another process, multiwalled carbon nanotubes were synthesized at 350°C by the solvothermal catalytic reaction of CgCle with metallic potassium (Fig. 2) [7]. 

We have developed the solvothermal synthesis as a convenient approach for controlling morphology, by which non-oxides nanomaterials, such as nanoparticles, one-dimensional nanomaterials and those with very special shapes have been fabricated, which include nano-metered tubes, rods, wires, balls, hollow spheres and peanut-like nanostructures, etc. 

In addition to the catalytic solvothermal synthesis of carbon nanotubes (Fig. 2) [7], SiC nanowires and tubular structures (Fig. 8) were prepared through a solvothermal reduction-carburization route using silicon powders and CCI4 as Si and carbon sources [20], Si3N4 nanorods were also prepared with a similar process [12]. 

Hou Y. L. and Gao G., Solvothermal Synthesis and Magnetic Properties of Polymer Protected Iron and Nickel Nanocrystals, submitted to J. Mater. Chem. 

Hydrothermal/solvethermal s)mthesis of RMO3 is also extensively adopted, by virtue of the low reaction temperature and well-crystallized products. Vazquez-Vazquez and Lopez-Quintela (2006) reported the solvothermal synthesis of Lai j-A MnOs (A = Ca, Sr, Ba) NPs in benzyl alcohol and acetophenone. The obtained precipitate was annealed to form crystalline products and acetophenone was found to be more suited to obtain clean perovskite phase. Zhu et al. (2008a) prepared single-crystalline YbMnOs and LuMnOa nanoplates via hydrothermal method. The products were found to be hexagonal phases. A possible formation mechanism was proposed, which involves the formation of ROOH phase as intermediate. 

With the wide use of hydrothermal and solvothermal synthesis, many polyoxogermanates with unique stmctures have been prepared. PolyoxoaUcoxovanadium germanate, (NH4)2[H2V9Ge8O26(L)6]-0.65H2O (H2T = HOCH2CH2-... 

The synthesis is in two steps (i) the neutralization of R-COOH with a base, such as ammonia, NaOH, or KOH (Equation 3.2) and (ii) the reaction of the resulting solution with the rare earth salts (Equation 3.3). The most commonly used salts are rare earth nitrates, chlorides, and perchlorates, largely because of their good solubility in water or in the polar solvents (THE, MeOH, EtOH, MeCN, DME, and DMSO). The synthesis can be accomplished under either ambient conditions or by solvothermal synthesis. 

Solvothermal techniques have been extensively developed for the synthesis of metal oxides [149-152]. Unlike many other synthetic techniques, solvothermal synthesis concerns a much milder and softer chemistry conducted at low temperatures. The mild and soft conditions make it possible to leave polychalcogen building-blocks intact while they reorganize themselves to form various new structures, many of which might be promising for applications in catalysis, electronic, magnetic, optical and thermoelectronic devices [153-155]. They also allow the formation and isolation of phases that may not be accessible at higher temperatures because of their metastable nature [156, 157]. 

Yang, Y., Matsubara, S., Xiong, L., Hayakawa, T. and Nogami, M. (2007). Solvothermal synthesis of multiple shapes of silver nanoparticles and their SERS properties. J. Phys. Chem. C 111 9095-9104. 

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