Estimation of Lattice Strain and Optical Properties of Scheelite-Type AWO4 (A = Ca, Sr, Ba) Nanocrystalline Materials Synthesized by Mechanical Activation

We reports the estimated lattice strain and optical behavior of Scheelite-type AWO(4) (A = Ca, Sr, Ba) nanocrstalline synthesized by mechanical activation. The X-ray diffraction patterns of the synthesized samples were analyzed by Rietveld refinement. Rietveld refinement confirms that the structure of the AWO(4) (A = Ca, Sr, Ba) nanocrystallite samples are tetragonal with the space group I4(1)/a. The lattice constants, unit cell volume and tetragonality of the AWO(4) samples increase with increasing ionic radii of A-site cation. Average values of crystallite size and lattice strain were estimated using Williamson-Hall method. The direct band gap of the Scheelite-type AWO(4) samples increases with increase in ionic radii of A-site cations.