Fast, solid state, microwave-assisted, synthesis

6 Fast, solid state, microwave-assisted, synthesis. A short history of reactions carried out in the solid state under the influence of microwaves was reported by Kniep (1993) who presented this technique as characteristic of a fast solid-state chemistry and described the preparation of CuInS2 by using a method first developed by Whittaker and Mingos (1992) and extended by Landry and Barron(1993). Copper, indium and sulphur (all powders between 100 and 300 mesh) in a molar ratio 1 1 2 were thoroughly mixed and loaded into a silica ampoule. This, sealed under vacuum, was placed in a domestic microwave oven and irradiated at 400 W and 2450 MHz. 

A few more examples of microwave-assisted syntheses are reported here below. 

The synthesis of compounds such as MPS3 (M = Mn, Cd) was performed (Villanueva et al. 2004) in a device consisting of a silica ampoule divided into a Dewar zone (hot zone) and a non-insulated part (cold zone) which can be operated inside domestic microwave ovens. This has been described as a rapid method which involves a heat concentration within the Dewar zone that allows the required temperature for the reaction to be reached. In the specific case a mixture of S, P, and the metal gives MPS3 compounds. The temperature gradient assures the vapour phase transport to the cold zone MPS3 crystals are deposited within a few minutes in this zone. 

Synthetic reactions carried out in the liquid phase and using metal powders under microwave irradiation have been described and discussed by Whittaker and Mingos (2002). 

A fast synthesis for Zintl phase compounds Na3SbTe3, NaSbTe2, K3SbTe3 by microwave irradiation has been described by Zhou et al. (2004). 

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