Effect of mechanical activation on the formation of lead titanates from PbCO3 – TiO2 mixtures

摘要

PbTiO3 powders have been prepared by mild annealing (2h at 600°C) of PbCO3:TiO2 mixtures previously subjected to mechanical activation, while a thermal treatment of about 12h at T > 850°C is needed to obtain PbTiO3 from a physical mixture. Although the temperature and enthalpy of the DSC peak corresponding to PbCO3 decomposition are not affected by mechanical energy, in the case of the mechanically activated mixtures an exothermic event due to the reaction PbO + TiO2 → PbTiO3 shows up. Furthermore, SEM micrographs and the XRD line broadening allow to conclude that PbTiO3 powders obtained from activated mixtures are of nanometer size. PbTi3O7 has been prepared starting from mechanically activated PbCO3:3TiO2 mixtures by 1h annealing at 850°C while 100h at 800°C were required to yield this compound from unmilled mixtures.