This work shows how it is possible to orientate powder grain morphology characteristicsthrough synthesis conditions both for as-synthesized powders (T = 115°C) and for calcinedpowders (T = 800 or 1100°C). The chosen example deals with the synthesis of fine yttria powders,using chemical methods. As a first point of interest, the preparation of the as-synthesized powder isdiscussed. A sol-gel method has been developed in which the chemical nature of the yttriumchelating agent and the [chelating agent/Y] relative concentration are the two main parameters.Depending on these conditions, very different grain morphologies were obtained, needles, platelets,gel-like, in relation to the chemical and structural composition of these precursor powders. Thesecond point of interest deals with the morphology of the yttria powder obtained after thermaltreatment of these precursors at high temperature. In some cases, the original morphologies weremaintained all over the calcining treatment whereas chemical composition changes were large.Thermodynamics consideration are also proposed to explain the final grain evolution at 1100°C.This yttria study case shows that a "memory effect" can actually be observed all over a largetemperature range when the synthesis conditions constrain enough the precursor grain formationfrom a chemical and structural point of view< Leer menos