CHEMICAL FORMS OF HYDROXYLS ON IN ZIRCONIA - AN FT-IR STUDY/

The hydroxyls groups of a heat-treated sample of zirconia powder (1170 K, 24h in O-2/H2O) were studied by FT-IR transmission spectroscopy an d compared with those of 'as-received' and air annealed zirconia sampl es. The surface studies were driven 'in situ' in a cell allowing heat treatments under either dynamical vacuum (10(-6) hPa) or controlled at mosphere, e.g. deuterium. The hydroxyls on the 'as-received' sample we re quickly exchanged by! OD when, after deuteriation of the sample hea t treated in water atmosphere, hydrosyls are still visible. Twenty-fiv e percent of them could not be exchanged even after a 4 h extension of the deuteriation process. As a counter-proof in the case of an air tr eated sample a complete deuteriation of the whole hydroxyls was observ ed. This difference clearly manifests that, in water annealed zirconia , H species have entered the bulk of the material where they are trapp ed. (C) 1998 Elsevier Science Limited. All sights reserved.