Structural characterization and photoluminescence behavior of pure and doped potassium strontium niobates ceramics with tetragonal tungsten-bronze structure

KSr2Nb5O15 and K(1.2)Sr(1.6)Ln(0.2)Nb(5)O(15) (Ln = La, Pr, and Nd) were synthesized by the Pechini method and calcined at 1373 K for 10 h under air atmosphere. Rietveld refinements indicated the presence of structural defects in both KSN and KSN-Ln, especially distortions in O-Nb-O and Nb-O-Nb bonds. Modifications in bond distances of [NbO6] clusters were also confirmed by Raman spectroscopy. Ultraviolet-visible absorption spectra and photoluminescence profiles were influenced by lanthanide atoms in the band structure of modified KSN materials, creating new defects and intermediary energy levels within the band gap. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.