Purely solid–solid reactions are encountered during materials processing, e.g., reactive sintering of ceramics, cement production, mechanical alloying, and electronic device fabrication. Driven mainly by Gibbs energy of the reaction, the kinetics of the reactions are broadly controlled by two factors, the rate of diffusion and that of reactions at the interfaces. The reaction mechanism involves the transport of reactants through the product layer, as in the case of a core–shell morphology. Nucleation of the reaction product plays an important role in solid–solid reaction kinetics. In Part 1, the theoretical considerations for these reactions are presented, along with examples from the synthesis of oxide ceramic, silicides, and borides. The mechanism of solid–solid reactions in mechanical alloying and mechanochemical synthesis has been elucidated.

Part 2 deals with the experimental methods for investigating solid–solid reactions. The classical diffusion couple experiments are discussed in detail along with the mathematical analyses of the results. A new method for measuring interdiffusivities in the case of oxide systems by the solid-state galvanic cell method is presented. A novel application of high-temperature X-ray diffraction method for interdiffusion studies of oxide systems by following the characteristic peaks of the products formed is also described in this part.

Part 3 presents a case study of the oxidation of magnetite particles to hematite.