Structural and vibrational studies of Ca-doped Ba2TiSi2O8 ceramics

Polycrystalline ceramic samples of calcium (Ca2+) substituted barium titanium silicate mineral (fresnoite) of general formula Ba2−xCaxTiSi2O8 (x = 0.0, 0.2, 0.4, 0.8 and 1), have been prepared by standard solid state reaction method using high purity oxides and carbonates. The formation of the single phase compound and its structural parameters were investigated by X-ray diffraction followed by Rietveld refinement. The lattice parameters calculated using the Rietveld refinement analysis are better than that of the earlier report so far. Raman spectra measured at 300 K for tetragonal Ba2−xCaxTiSi2O8 ceramics present well defined modes. The variations of the Raman modes with the different concentration of Ca2+ substitution have been studied in detail.