Influence of Eu substitution for Gd on the structure and photoluminescent properties of (Gd1-xEux)2Ti2O7 pyrochlore solid solutions

This paper presents a study of the synthesis and structural properties of the pyrochlore-type titanates (Gd1-xEux)(2)Ti2O7. Six compositions with 0 <= x <= 1 were prepared by solid-state reaction with thermal treatments at 1000 and 1200 degrees C under atmospheric pressure conditions. All the products were systematically characterized by X-ray powder diffraction (XRD), Raman spectroscopy, photoluminescence (PL) and photoluminescent excitation spectra (PLE). Structural refinements of X-ray powder diffraction data using Rietveld method show that all compounds of the (Gd1-xEux)(2)Ti2O7 solid solution crystallize in a pyrochlore structure. The lattice parameters increase linearly with increasing Eu content in agreement with Vegard's rule. PL spectra show that the characteristic peaks correspond to the f-f transition D-5(0)-F-7(J) (J = 1, 2, 3 and 4) of Eu3+. The effect of Eu3+ ions concentration on the optical properties, namely, photoluminescence emission, is measured and discussed. The oxides exhibit higher PL intensity with the Eu3+ ion concentration and strong orange emission at 589 nm (D-5(0)-F-7(1)) corresponding to the magnetic dipole transition. (C) 2017 The Society of Powder. Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.