Synthesis and luminescent properties of monodispersed spherical Ce(IV)-Gd(III)-Eu(III) oxides

CECILIA SORBELLO; M. JOBBAGY; B. C. BARJA

Congreso; ICFE2012 (Internacional Conference of f Elements); 2012

Summary Lanthanides are widely used to develop phosphors with technological applications in the field of light conversion: luminescent lamps, diodes, and optical fibers. A family of ternary compounds with the general formula Ce0.95-xGdxEu0.05O2-, with 0≤ x ≤0.95 was synthesized by the urea method. Spherical and monodispersed luminescent microparticles were obtained. Important changes in the energy transfer mechanisms take place in the ternary mixtures and the emission of Eu(III) is no longer assisted by the host when compared with samples in which x = 0 and x = 0.95. Introduction: Eu (III) based phosphors are used as source of red light, due to its sharp emission centred at ∼610 nm (5D0  7F2). Nowadays, increasing efforts are focused on the synthesis of new materials by variation of the host matrices. Well tunned morphological properties are needed to control the emission performance of the material. The homogeneous urea method has proved to be a suitable tool to prepare monodispersed submicrometric spherical particles of mixed oxides. Materials and Methods: Spherical monodisperse hydroxocarbonate precursors were obtained by the homogeneous urea method [1], reaching after annealing at 1273K the formula Ce0.95-xGdxEu0.05O2- with 0 ≤ x ≤ 0.95. The samples are named CGX, being X the % Gd(III)/[Gd(III)+Ce(IV)]. High resolution scanning electron microscopy (HRSEM) coupled with Energy dispersive X-ray spectroscopy (EDS) was performed. Average particle size = 100 nm. Results and Discussion: The XRD studies indicate that for X > 0.5 (See Figure 2) only one C-type phase exists. For X < 0.2, a doped CeO2-like phase (cerianite) prevails while, presumably two segregated phases are present for 0.2< X