Mechanical alloying of oxides.

Mechanical alloying is a synthesis method using high energy ball milling which allows to prepare a large number of materials, often in a metastable form, with a nanometric grain size. Moreover, high energy ball-milling modifies the chemical reactivity of solids and induces chemical reactions and solid state phase transformations : amorphization, allotropic transformations, order-disorder transitions. This paper reports results concerning the ball-milling effects applied to oxides. Various examples illustrating the preparation of oxide compounds and solid solutions are reported. Some of these products are non-equilibrium phases and can be prepared by other methods only at high pressure or/and high temperature. The chemical reactions and phase transformations can be influenced by the milling environment (steel or zirconia), more especially when reduction reactions occur between oxide particles and milling tools.