Structural, electronic, optical properties and first-principles calculations of Sr1-xCaxWO4 ceramics

Mohammed Ait Haddouch, Youssef Tamraoui, Fatima-Ezzahra Mirinioui, Youssef Aharbil, Hicham Labrim, Bouchaib Manoun, Abdelilah Benyoussef, Saïd Benmokhtar
2019 Mediterranean Journal of Chemistry  
<p>A series of strontium calcium tungstates Sr<sub>1-x</sub>Ca<sub>x</sub>WO<sub>4</sub> powders with (x = 0; 0.25; 0.5; 0.75 and 1.0) were prepared by solid-state reaction method and analyzed by X-ray diffraction (XRD). All these compositions possess a tetragonal scheelite structure with I4<sub>1</sub>/a space group. Raman active vibrational modes in the range from 20 to 1000 cm<sup>-1 </sup>of the series Sr<sub>1-x</sub>Ca<sub>x</sub>WO<sub>4</sub> with tetragonal structure exhibit 13 modes
more » ... exhibit 13 modes in arrangement with the Group theory analysis of structural Raman-active modes. The optical properties were investigated using the diffuse reflectance UV–visible absorbance spectrum. Based on Density Functional Theory (DFT) and using full Potential-linearized Augmented Plane Wave (FP-LAPW) method with the Local Density Approximation and the Generalized Gradient Approximation (GGA), implemented in the Wien2k package, we have investigated electronic and optical properties of all the compositions. The results indicate a decrease in the values of the optical direct bandgap (from 4.29 to 3.87 eV) with the increase of Ca into SrWO<sub>4</sub> lattice, which is in good agreement with our experimental results.</p>
doi:10.13171/mjc93191005355mah/yt fatcat:iauu63nlubhkbpikwkth5lmqym