Photoluminescence properties of La3+ ion-doped YInGe2O7 self-activated phosphor

A color-tunable La3+ ion-doped YInGe2O7 self-activated phosphor has been synthesized using a high energy vibrating milled solid state reaction with metal oxides and calcined at 1200 degrees C for 10 h in air. The structure and optical properties of (Y1-xLax)InGe2O7 phosphors have been investigated. XRD results show that all the diffraction peaks keep the monoclinic YInGe2O7 phase when the La3+ ion concentration is increased up to 3 mol%. The UV-visible absorption spectra analysis indicated that the intensities of absorption band at 280-450 nm corresponding to the oxygen deficient center of the GeO4 anion were increased and then decreased with increasing the La3+ ion concentrations. Under an excitation of 263 nm, the emission intensities of 487 and 545 nm corresponding to the single ionized V-o defect emission are increased and then decreased as the La3+ ion concentration is increased. The maximum intensity for these two emission peaks was observed when the La3+ ion concentration is 0.3 mol%. This is due to the lattice distortion and induced an increase in the degree of tensile strain, which causes the amount of oxygen vacancies to increase when the Y3+ ion was substituted by the La3+ ion. In addition, the CIE color coordinates changed from a blue --> greenish --> bluish region as the La3+ ion concentration increased from 0 to 3 mol%. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.