To investigate the annealing temperature and stoichiometry effects, on crystal growth and optical properties of lead doped yttrium titanate, we prepared the stoichiometric samples:Y2(1-x) Pb2xTi2O7-δ, where x = 0, 10, 20, 30 and 40% (YPTx), using the sol gel method. Phase transformations in the samples were followed by X-ray diffraction (XRD), Raman and UV-Vis spectroscopies, and transmission electron microscopy. XRD analysis shows that the undoped sample exhibits the pyrochlore structure with an unit cell parameter of 10.096 Å, with few traces of the TiO2 rutile phase. Moreover, coexisting Y2Ti2O7, PbTi3O7 and PbTiO3 phases, depending on x(Pb2+), are observed; all these phases are stable in the corresponding range of Pb2+concentration. The reflectance UV-vis spectra show the presence of a fundamental band in pure and doped samples, assigned to the pure phase Y2Ti2O7, and a defect band in YT and YPT10; the latter may be assigned to a Frenkel-pair associated with cation defects.

Keywords: Pyrochlore-type yttrium titanate (Y2Ti2O7), Sol-gel, Optical properties, X-ray diffraction.