Abstract Abstract Lead zirconate titanate (PZT) thick films with a thickness of 10 μm were subjected to rapid open-air sintering and the compositional and structural characteristics were investigated. The results show that the evaporation of lead not only alters the sintering characteristic of thick films, but also causes the formation of separate phases from the bulk PZT. The activation energy for the evaporation process is about 2 eV which is higher than that for self-diffusion of lead. The rapid open-air sintering is in fact a competitive process in which both sintering and evaporation are present. Moreover, the titanium and zirconium exhibit different diffusion features during rapid sintering: titanium tends to diffuse into alumina substrates but zirconium is rejected by the substrates, which causes the composition of films to shift towards the tetragonal phase. The diffusion of aluminium into PZT was also observed, which caused the formation of an unknown phase above 1200 °C.