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Wet Chemical Methods for Nanop article Synthesis
Published in Vidya Nand Singh, Chemical Methods for Processing Nanomaterials, 2021
Other than aqueous solutions, nonaqueous organic solvents have also been used in the solvothermal reaction, which is similar to the hydrothermal synthesis. The commonly used organic solvents in solvothermal synthesis are methanol [21], toluene [22], 1,4-butanediol [23], and amines [24]. As a substitute to hydrothermal reaction, the solvothermal reaction can provide products at relatively lower temperatures and pressures. The precursors, which are sensitive to water, can also be handled in solvothermal reactions easily [25]. The products obtained from the solvothermal reaction are phase pure, free from foreign anions with controlled morphology [26-29]. There are afew more factors that can significantly affect the crystal nucleation and nanomaterials growth during hydrothermal/solvothermal synthesis. They are-precursors [30, 31], reaction time [32], additives [33], and filling factor, i.e., the ratio of the volume filled with solution to the total reactor volume [34]. The advantage of hydrothermal/solvothermal process is that the product can be formed directly from the solution. Different starting materials (precursor) and reaction conditions can help to control particle size and shapes. The resulting powers are highly reactive, which aid in low temperature sintering. The limitation of the hydrothermal/solvothermal method is that prior knowledge of solubility of precursor materials is required. The slurries in hydrothermal/solvothermal reactions are potentially corrosive. Accidental explosion of the high-pressure vessel (hydrothermal bomb) cannot be ruled out if proper care is not taken.
Fabrication and Classification of Nanomaterials
Published in Vladimir I. Gavrilenko, Optics of Nanomaterials, 2019
Template-assisted synthesis and solvothermal synthesis are frequently used methods for the preparation of hollow nanostuctures (Deng and Lee, 2008). Template-assisted synthesis relies on the template to sculpt the product morphology. It offers ease of morphology control through template selection. A number of removable templates can be used to generate simple hollow nanostructures. However, template-assisted synthesis is not without problems, such as difficulty in template fabrication, the possibility of product deconstruction during the template removal process, shortage of templates for generating hollow structures with complex interiors, and multistep and costly operations. By comparison, solvothermal synthesis has notable advantages such as simple and straightforward operations and low-cost, scalable production. It has been successfully used in the preparation of hollow spheres, hollow octahedra, and hollow boxes. The morphology of nanostructures obtained by solvothermal methods is strongly dependent on the solvents used, the ions involved, acidity, and other environmental factors. Quite unlike template-assisted synthesis, there is no good method to predict the product morphology a priori in a solvothermal synthesis.
Ceramics: Processing, Properties, and Applications
Published in Noureddine Ramdani, Polymer and Ceramic Composite Materials, 2019
Solvothermal research was first developed during laboratory simulations of natural hydrothermal phenomena. Later, the hydrothermal synthesis was discovered as an important process for synthetizing ceramic material. This method used single- or heterogeneous-phase reactions in the presence of either aqueous or nonaqueous solvent above room temperature and at pressures higher than 1 atm in a closed reactor. Solvothermal synthesis is mainly controlled by two key parameters: thermodynamic parameters and kinetic parameters. This process facilitates the production of very complex ceramics having the desired physicochemical properties in a temperature range of 100 and 400°C without any annealing step. Three main synthetic routes can be distinguished in solvothermal processes, including the precipitation of the solid phase when the reactants are soluble in the solvent, the decomposition of the insoluble precursor in the solvent, and crystallization of amorphous starting ceramic materials (Figure 2.7) [26].
Synthesis and modelling of the mechanical properties of Ag, Au and Cu nanowires
Published in Science and Technology of Advanced Materials, 2019
Nurul Akmal Che Lah, Sonia Trigueros
The hydro/solvothermal synthesis involves a direct chemical reaction of the precursors in solution. It produced metallic nanowires at high yield. The undesired by-products, such as nanoparticles or other nanostructures, are relatively minor and can be easily precipitated by centrifugation. Furthermore, this method does not require acidic or alkaline reagents for removing the synthesis template. Besides, the hydro/solvothermal synthesis is relatively simple and inexpensive, and its products depend solely on the types of the chosen chemical reagents. This approach is more attractive than the solid-state reaction (top-down method), as it guarantees mixing of the starting reagents at the atomic level, leading to a better control over the nanowire products.
An overview on synthesis procedures of nanoparticles applied to enhanced oil recovery
Published in Petroleum Science and Technology, 2022
Mariana Schneider, Júlia da Silveira Salla, Rafael Peralta Muniz Moreira, Regina de Fatima Peralta Muniz Moreira
In this technique, the solid precursors are mixed in pure water and agitated until the solution is completely homogenized. If the solvent is different from water, the process is called solvothermal synthesis. The method involves heating the reactants in a particular solvent in a high-pressure system and temperature in the range of 150–300 °C, for long periods (12–24 h). Table 1 summarizes recent papers dealing with nanoparticles synthesized by hydrothermal and solvothermal methods, and applied to EOR.