Structural investigation and improvement of photoluminescence properties in Ba(ZrxTi1 x)O3 powders synthesized by the solid state reaction method

In this paper, Ba(ZrxTi1-x)O3 powders with different (x) compositions were synthesized by the solid state reaction method and their structure and improvement of photoluminescence (PL) properties with the Ti substitution by Zrwere discussed. The structural investigation of these powderswas performed by means of X-ray diffraction (XRD) and Fourier transformRaman (FT-Raman) spectroscopy. Their optical propertieswere monitored by ultravioletevisible (UVevis) absorption spectroscopy and PL measurements. XRD patterns indicated that the powders with x = 0 and 0.1 have a tetragonal structure while compositions with x 0.2 exhibit cubic structure. FT-Raman spectra revealed that the replacement of Ti by Zr significantly reduced the intensity of the Raman activemodes. This behavior is related to the increase of undistorted [ZrO6] clusters in the globalmatrix at short range and decrease in local concentration of distorted octahedral [TiO6] clusters. UV evis absorption spectra shownthe presence of intermediaryenergy levels between the valence band(VB) and the conduction band (BC). These intermediary electronic levels aremainly related to 2p orbitals ofOatoms, 4d orbitals of Zr atoms and 3d orbitals of Ti atoms between the VB and CB. A significant improvement in PL properties of Ba(ZrxTi1-x)O3 powders was observed with an increase of undistorted [ZrO6] clusters in the lattice. Finally,we propose possible wideband models based on intermediary energy deep and shallowlevels to explain the PL behavior at room temperature