Synthesis of Nano-Cobaltites, -Ferrites, -Chromites, and -Manganites

6 Synthesis of Nano-Cobaltites, -Ferrites, -Chromites, and -Manganites 

The discovery, through serendipity, that the combustion of iron hydrazine carboxylate yields nano-iron oxide led to the preparation of various nanosize oxide materials by the thermal reactivity of metal hydrazine carbox-ylates. Hitherto, oxide materials prepared by conventional ceramic techniques used hydroxides, carbonates, nitrates, or oxalates as starting materials. The procedure involves their repeated pulverization and 

The formation of cobaltites (MC02O4) from the combustion of mixed metal oxalate/acetate hydrazine complexes and solid solutions of hydra-zinium metal hydrazine carboxylate hydrates have been discussed in Chapters 3 and 4, respectively (Sections 3.2.4.1, 3.2.6 and 4.6). The final product, confirmed by X-ray diffraction pattern, shows the characteristics of cobaltite spinels. Similar to cobaltites, mixed metal oxalate/acetate hydrazines complexes undergo single-step decomposition to form 

Mixed metal oxalate hydrates do not yield ferrites at such low temperatures. However, complex formation with hydrazine makes it possible to obtain ferrites from the oxalates precursors at low temperatures of —150 °C. This shows that the exothermic decomposition of hydrazine plays a vital role in the formation of these spinels at such temperatures. Properties of the ferrites formed are summarized in Table 6.7. 

Cobaltites and ferrites also find application as catalysts in dehydrogenation reactions. As a consequence, ferrites with large surface area are needed to function effectively as catalysts. For example, hydrogen peroxide, a well-known disinfectant that liberates nascent oxygen is widely used in operation theatres of hospitals. It is essential that to 

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