Hydrothermal route, microwave

The aim of this paper is to present the use of a microwave digestor to prepare nanopowders via hydrothermal route. In the field of biomaterials the researchers (due to some problems with the traditional materials) are looking for the design of biomaterials with surface properties similar to physiological bone (grain sizes in the nanometric range [5]). This would aid in the formation of new bone at the tissue/biomaterial interface and therefore improve implant efficacy. With the advent of nanostructured materials (materials with grains sizes less than 100 nm in at least... 

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. 

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

Khollam, Y.B., Deshpande, A. S., Patil, A. J., Potdar, H. S., Deshpande, S. B. Date, S. K. (2001). Synthesis of yttria stabilized cubic zirconia (YSZ) powders by microwave-hydrothermal route. Materials Chemistry and Physics. Vol. 71, pp. 235. 

The LaMnOs and Lao.sAgo.2Mn03 samples, prepared under microwaves irradiation at atmospheric pressure (MW) or synthesised by microwaves-assisted hydrothermal accelerated solid state synthesis (MWhyd), exhibited higher specific surface areas (19 m /g for MW LaMnOs, 16 m /g for MW Lao,8Ago,2Mn03 29 m /g for for MWhyd LaMnOs, and 25 m /g for MW Lao,8Ago,2Mn03) than the same samples prepared by conventional routes [8]. 

In this part of the chapter, we will focus on microwave application in the synthesis of perovskite materials (ABOs-type oxides). There are many examples in the literature of chemical routes that can be applied in the synthesis of perovskite oxides, such as hydrothermal, sol-gel, combustion, or citrate processing, among others (see Figure 5.1) [11]. Table 5.1 compiles some detailed information about microwave-assisted synthesis methods of perovskite materials made by selected research groups. 

A large number of reports have probed the role of various factors in the synthesis of CuS nanoparticles using different routes [see Table 3 and references there in]. The nature of sulphur source has also been probed. H2S has been the most direct ore. However, many alternate sulphur sources have been tried that decompose to H2S, elemental sulphur or S ions. Therefore, reactions conditions were optimized using microwave irradiation, sonicator, hydrothermal, solvothermal (pressure temperature), y irradiation, etc. using a number of Cu and S sources. 

Many researchers have identified the difference in the presence of hot spots (which locally enhance or promote some selected reactions or transformations). The narrow temperature distribution obtained by simulation can justify the formation of nanoparticles (having a narrower particle size distribution) with respect to conventionally heated synthetic routes in case of nucleation and growth of nanoparticles (microwave hydrothermal synthesis). The large-scale production of nanoparticles requires the development of microwave reactors, which can reflect the laboratory temperature profile homogeneity. It will provide a new dedicated eontinuous-flow reactor, made of two twin prismatic applicators for a microwave-assisted process in aqueous solution. The reactor can produce upto 1000 L/day of nanoparticles eolloi-dal suspension at ambient pressirre and relatively low temperature and henee, it ean be considered a green chemistry approach. 

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