Synthesis and Study of the Effect of Ba(2+) Cations Substitution with Sr(2+) Cations on Structural and Optical Properties of Ba(2−x)Sr(x)ZnWO(6) Double Perovskite Oxides (x = 0.00, 0.25, 0.50, 0.75, 1.00)

The effect of Sr(2+) substitution on the morphology, crystal structure, and optical properties of double perovskite oxide Ba(2−x)Sr(x)ZnWO(6) (x = 0.00, 0.25, 0.50, 0.75, 1.00) were investigated. Scanning electronic microscopy demonstrated that all samples have similar microstructure morphology but differ in the range of grain sizes. X-ray diffraction measurements indicated that these materials crystallize in a (Fm-3m) cubic crystal structure, and also confirmed the tolerance factor. Rietveld analysis revealed that the lattice parameter decreased from 8.11834 to 8.039361 Å when the substitution of Ba(2+) with Sr(2+) cations increased from zero to 100%. Fourier transform infrared (FTIR) and Raman spectroscopies displayed a symmetric stretching vibration of WO(6) octahedra at 825 cm(−1), and an anti-symmetric stretching mode of WO(6) was observed by FTIR at 620 cm(−1). A strong peak at 420 cm(−1) was also observed in the Raman spectra and is due to the W–O–W bending vibration modes. UV-Vis diffuse reflectance spectroscopy was carried out for the series, and the band gap energy decreased from 3.27 eV for Ba(2)ZnWO(6) to 3.02 and 3.06 eV for Ba(1.75)Sr(0.25)ZnWO(6) and Ba(1.5)Sr(0.5)ZnWO(6), respectively. The excitation and emission photoluminescence properties were investigated at room temperature.