fig3

Figure 3. (A) XRD patterns of BTC ceramics, with enlarged views of (111), (002), and (200) diffraction peaks; (B) Raman spectra of BT, BC4T, and BTC4 ceramics measured at room temperature. Synchrotron powder XRD patterns of (C) BT, (D) BC4T, and (E) BTC4 ceramics, with accompanying Rietveld refinement results. A blue trace in the residual plot highlights the deviations between the measured and computed values. The positions of Bragg peaks are marked by vertical green and orange indicators, serving as reference points for crystallographic analysis. The primary diffraction peaks of all samples align well with theoretical Bragg positions (vertical ticks), confirming phase integrity. The refined profiles exhibit excellent agreement with peak positions and relative intensities, with high reliability factors. The illustration in Figure 3C shows the variation of the c/a ratio with Ca doping content for the BCT and BTC ceramics, as calculated from Rietveld refinement results. For the BTC ceramics, the c/a ratio was obtained by averaging the c/a values of the tetragonal and cubic phases. BTC: BaTi_100-xCa_xO₃; XRD: X-ray powder diffraction; BT: BaTiO₃; BCT: Ba_100-xCa_xTiO₃.