Detailed structure analyses on Cobalt doped PbTiO₃ powders

The identification of the defects and secondary phases which significantly affect the material properties are of crucial importance. In this study, a systematic structure examination of PbTiO₃ and cobalt doped PbTiO₃ powder ceramics was carried out. X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), Raman, and electron paramagnetic resonance (EPR) spectroscopies were applied along with nonsimultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The doped and undoped PbTiO₃ materials were synthesized via a practical sol-gel route that takes place at 50 °C. The perovskite formation for both materials was verified. The dislocation density of cobalt doped PbTiO₃ was found to be 0.0121 nm^-2 while it was 0.00239 nm^-2 for the undoped material. Besides, a strong strain effect was observed for cobalt doped PbTiO₃ via XRD. This was attributed to the Co₃O₄ phase which was detected through EPR and FT-IR analyses. The formation of the Co₃O₄ phase during synthesis revealed the previously unexpected nonimproved ferroelectric behavior for cobalt doped PbTiO₃. The dielectric constant and the dielectric loss (tan δ) of cobalt doped PbTiO₃ were estimated as 1066 and 0.8370, respectively.