Red-emitting SrGe4O9:Eu3+ phosphors obtained by combustion synthesis

Abstract

Abstract In this work, red-emitting Strontium-Germanate SrGe 4 O 9 :xEu 3+ (SGO) phosphors doped with x = 0%, 1%, 3% and 5 at% of Eu were obtained by a combustion method. The X-ray diffraction patterns of these phosphors revealed that all the samples have a trigonal phase. Morphological studies by scanning electron microscopy (SEM) showed irregular coalesced grains that formed with sizes in the range of 0.14–0.22 µm. Furthermore, the degree of coalescence among particles increased as the content of Eu dopant augments. The optical band gap (E g ) of pure and Eu-doped SGO were calculated with Tauc plots and was observed a decrease of E g as the Eu concentration increases. Also, the emission spectra of Eu-doped SGO (under UV excitation at 303 nm) revealed that their luminescence centered at 611 nm increased as the Eu content is raised, with a maximum luminescence was observed for the sample doped with 3 at% of Eu. Finally, the CIE (Commission Internationale de l′Eclairage) chromaticity coordinates of (0.56, 0.34) were calculated for the sample with the highest luminescence, which did not change even for Eu concentrations as high as 5 at%. Due to their intense red emission and stability for CIE coordinates, SrGe 4 O 9 :xEu 3+ phosphors could be good candidates for the generation of the red component in solid state lighting devices.