Investigation of the structural and optical properties of sol gel processed Ho-doped BaTiO₃ ceramics

The pure BaTiO3 and Ho doped BaTiO3 (Ba1-xHoxTiO3 with x = 0, 0.25, 0.50, 0.75, 1, 1.5 and 2%), powders were prepared through the sol-gel process and structurally characterized by Thermogravimetric analysis (TGA), Differential thermal analysis (DTA), X-Ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and Raman spectroscopy. The optical properties have been investigated using Ultraviolet-Visible (UV-Vis) transmittance-reflectance spectroscopy. X-ray diffraction (XRD). The results revealed that the prepared powders, calcined at 1000 degrees C for 4 hours, crystallized in the pure perovskite structure without the presence of secondary phases and showed a slight transition from the quadratic phase (pure BT) to the pseudo-cubic phase for the doped samples. From these results, we can also notice that Ho may occupy both Ba and Ti crystallographic sites. Raman and Fourier Transform Infrared (FT-IR) results are in accordance with those obtained from XRD characterizations. The values of the bandgap energies for the doped samples are lower than that of the pure BaTiO3 (3.26 eV), thus confirming energy softening effect of Ho.