Synthesis and characterization of nm-sized PbTiO₃ crystallites

Abstract

In this work attempt is made to synthesize PbTiO₃(PT) nanopowder by low temperature direct synthesis (LTDS) method already introduced by Wada et al. [8]. Various samples were prepared by precipitating a strong acidic Ti-bearing solution in an alkaline solution obtained by dissolution of Pb(NO₃)₂ in a KOH solution (pH = 14). The samples were synthesized with varying Pb/Ti atomic ratios (1.0, 2.7, 6.5 and 10) at 70 ^∘C. XRD, TEM, FTIR and DTA/TG techniques were utilized to characterize the obtained powders. The formation of single phase PT was not confirmed for the non-heat treated as precipitated samples in contrast with the results obtained by Wada et al. [8] for BaTiO₃. Further, for the as precipitated samples not subjected to washing process with a Pb/Ti ratio above 1, the formation of unknown crystalline phase/s was detected due to the reaction taken place between Ti-bearing solution and potassium plumbate formed by dissolution of Pb(NO₃)₂ in KOH solution. Applying washing process for these samples gave rise to the partial destruction of the observed structure/s and the formation of an amorphous phase as confirmed by XRD and TEM results. However, calcination of the as precipitated/washed samples at 500 ^∘C and 700 ^∘C for 1 hour gave rise to the formation of PT nanopowder as the main phase with average crystallite sizes in the range of about 11–14.5 nm respectively. Single phase PT nanopowder of an average crystallite size of 13 nm was formed for the sample with a Pb/Ti ratio = 1 when calcined at 500 ^∘C for 1 hour. For the calcined samples with Pb/Ti ratios above 1 the formation of PbO as the second phase, however, was also detected and its level of formation was found to be related to the Pb/Ti ratio.