Pechini process

The method is normally performed as follows [32,39] an aqueous solution of suitable oxides or salts is mixed with an a-hydroxycarboxylic acid, such as citric acid, and EG is added to the solution. At heating, an esterification process runs in the system leading to the formation of a stable gel in which the metal ions remain fixed. In the modified Pechini process, ethylenediaminetetraacetic acid (EDTA) has been used to replace citric acid due to its stronger chelating power. 

Another important sol—gel solution chemistry is that of the Pechini process [39]. Here metals are complexed in aqueous solution by citric acid. Then a polyalcohollike ethylene glycol is added and the solution heated to 150 to 250°C, causing polyesterification of the metal chelates, which results in a gel. The gel is then thermally decomposed to produce a mixed oxide with very fine crystallites, typically 20 to 50 nm, clustered into aggregates. Over 100 different mixed oxide compositions have been prepared by this method. 

An important nonhydrolytic chemical process is the so-called Pechini process or in sim polymerizable complex (IPC) [262]. This process is based on the ability of polycarboxylic acids, particularly citric acid (CA), to form very stable water-soluble... 

Figure 3-1. Schematic illustration showing the solution chemistry and reactions involved in the Pechini process (Liu, 1995).

Agarwal V., Liu M. Preparation of barium cerate-based thin films using a modified Pechini process. J. Mater. Sci. 1997 32 619-625... 

Chai Y.L., Ray D.T., Chen G.J., Chang Y.H. Synthesis of Lao.8Sro.2CoOo.5Nio sOa-i thin films for high sensitivity CO sensing material using the Pechini process. J. Alloys Compounds 2002 333 147-153... 

Free Radical Polymerization. In situ polymerization reactions of the monomers added to metal salt solution other than Pechini process were proposed. They utilize free radical polymerization of acrylamide (Gotor, 1993 Rao, 1995 Sin, 2000, 2002) or acryUc add (Mani, 1992). The gelation in a usual synthesis occurs due to the reaction between acrylamide and N- N= methylene-bis-acrylamide. Free radicals initiating the polymerization are created by hydrogen peroxide or azobisisobutyronitrile. Just solvated copper ions strongly inhibit polymerization and sufficient amount of EDTA (Sin, 2000) or dtric add (Gotor, 1993 Rao, 1995) should be added to chelate copper and possibly other metals. The clear advantage of this method is that in contrast to Pechini-type process, which enploys reversible polyesterification reaction, the polymer formation by free radical mechanism is irreversible process that can be conducted, in addition, at low temperatures. 

Quinelato AL, Longo E, Leite ER, et al. Synthesis and sintering of Zr02-Ce02 powder by use of polymeric precursor based on Pechini process. J Mater Sci. 2001 36 3825-30. 

Wu, S.Fl., Chen, Fl.L. 2003. The effects of heat-treatment temperature on the retention capacities of spinels prepared by the Pechini process, 119-121 134-138. 

Liu W, Farrington GC, Chaput F, Duhn B (1996) Synthesis and electrochemical studies of spinel phase LiMn204 cathode materials prepared by the Pechini process. J Electrochem Soc 143 879-884... 

Wu SH, Su HJ (2002) Electrochemical characteristics of partially cobalt-substituted LiMn2-yCoy04 spinels synthesized by Pechini process. Mater Chem Phys 78 189-195... 

Vivekanandhan S, Venkateswarlu M, Satyanarayana N (2005) Effect of different ethylene glycol precursors on the Pechini process for the synthesis of nano-crystalline LiNio.5Coo.5VO4 powders. Mater Chem Phys 91 54-59... 

Ramasamy Devaraj R, Karthikeyan K, Jeyasubramanian K (2013) Synthesis and properties of ZnO nanorods by modified Pechini process. Appl Nanosci 3 37 0... 

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