Investigation of structural phase evolution and dielectric response of Co-doped BaTiO₃

Abstract

In the present study, we have synthesized polycrystalline samples of BaTi[Formula: see text]CoxO3 (BTCO) ([Formula: see text], 0.01, 0.03, 0.05, 0.07 and 0.10) with standard solid state reaction technique. The obtained samples are characterized by X-ray diffraction (XRD) and Raman spectroscopy for structural study. The detailed structural analysis has been performed by Rietveld refinement using Fullprof program. We observed an increase in lattice parameters, which results due to substitution of Co[Formula: see text] with large ionic radii (0.9[Formula: see text]Å) for smaller ionic radii (0.6[Formula: see text]Å) Ti[Formula: see text]. Moreover, peak at 45.5∘ shifts to 45∘ on Co doping, which is due to structure phase transition from tetragonal to cubic. Raman study infers that the intensity of characteristic peaks decreases and line width increases with Co doping. The bands linked with the tetragonal structure (305[Formula: see text]cm[Formula: see text]) decreased due to the tetragonal-to-cubic phase transition with Co doping. Our structural study reveals the expansion of BTCO unit cell and tetragonal-to-cubic phase transformation takes place. The results from different characterization techniques are conclusive and show structural evolution with Co doping. The samples are further characterized by dielectric spectroscopy, dielectric measurement reveals the increase of dielectric constant and transition [Formula: see text]C is observed for Barium titanate (BaTiO3), whereas transition disappears with Co doping. Both temperature and frequency-dependent tangent loss is also studied.

Effects of the reaction temperature and Ba/Ti precursor ratio on the crystallite size of BaTiO3 in hydrothermal synthesis

“…2a) is particularly sensitive to the tetragonality of the crystal structure, with its intensity increasing when BaTiO 3 becomes more tetragonal. [20][21][22] Fig. 2b shows the variation of the relative integrated intensity of the peak at 307 cm −1 for BaTiO 3 versus the reaction temperature in hydrothermal synthesis with Ba/Ti precursor ratios of 4 : 1, 2 : 1 and 1 : 1.…”

A La and Nb co-doped BaTiO3 film with positive-temperature-coefficient of resistance for thermal protection of batteries

“…47,50 The integrated intensity of the peak at 307 cm À1 for each sample relative to that of the undoped BaTiO 3 sample has This journal is © The Royal Society of Chemistry 2022 been used to qualitatively evaluate the tetragonality aer La and/or Nb doping. 47,51,52 In Fig. 2b, the relative integrated intensities of the peak at 307 cm À1 are plotted vs. various doping elements and amounts.…”

Suppression of magnetic phase transition at high magnetic field and non-Debye's nature of nano-crystalline Gd$_2$CoMnO$_6$: a detail study of physical properties

“…The imaginary part is known as the loss factor. The lag between the change in polarization and the applied electric field makes the permittivity a complex entity given as: [45][46][47][48][49]…”