Mechanochemistry: from mechanical degradation to novel materials properties

ABSTRACTHigh-energy mechanical action applied to solid leads to destruction and diminution to the nanosize level. But on the otherhand, it can induce structural changes at the nanoscale and at the atomic level which can result in novel materials properties. In thiscontribution, case studies will be presented concerned with the tailoring of magnetic properties of mechanically treated nanomaterials.Emphasis is placed on materials that have been synthesized by mechanochemical means and on an improved understanding oftheir nanomagnetism in general. The associated local structural changes of the iron containing magnetic materials discussed inthe examples have been studied most suitably by 57 Fe Mossbauer nuclear probe spectroscopy whose results are supplemented bymeasurements of the magnetic properties of the mechanosynthesized nanomaterials.Key words : Mechanochemistry, Nanomagnetism, Core-shell model, Spinels, M o ssbauer spectroscopy 1. Introduction echanochemistry is concerned with the chemical behaviorof solids under the action of a mechanical influence.M. Carey Lea (1823-1897) can be considered as the foundingfather of the field. About 120 years ago, he published the firstsystematic studies of mechanically induced solid state reactionsinvolving the decomposition of copper, silver, and mercuryhalides.