Synthesis, Characterization and Photophysical Properties of Eu³⁺ Doped in BaMoO₄

Abstract

In this work Ba_0.99Eu_0.01MoO₄ (BEMO) powders were prepared by the first time by the Complex Polymerization Method. The structural and optical properties of the BEMO powders were characterized by Fourier Transform Infra-Red (FTIR), X-ray Diffraction (XRD), Raman Spectra, High-Resolution Scanning Electron Microscopy (HR-SEM) and Photoluminescent Measurements. XRD show a crystalline scheelite-type phase after the heat treatment at temperatures greater than 400 °C. The ionic radius of Eu³⁺ (0.109 nm) is lower than the Ba²⁺ (0.149 nm) one. This difference is responsible for the decrease in the lattice parameters of the BEMO compared to the pure BaMoO₄ matrix. This little difference in the lattice parameters show that Eu³⁺ is expected to occupy the Ba²⁺ site at different temperatures, stayed the tetragonal (S₄) symmetry characteristic of scheelite-type crystalline structures of BaMoO₄. The emission spectra of the samples, when excited at 394 nm, presented the ⁵D₁→⁷F_{0, 1 and 2} and ⁵D₀→⁷F_{0, 1, 2, 3 and 4} Eu³⁺ transitions at 523, 533, 554, 578, 589, 614, 652 and 699 nm, respectively. The emission spectra of the powders heat-treated at 800 and 900 °C showed a marked increase in its intensities compared to the materials heat-treated from 400 to 700 °C. The decay times for the sample were evaluated and all of them presented the average value of 0.61 ms. Eu³⁺ luminescence decay time follows one exponential curve indicating the presence of only one type of Eu³⁺ symmetry site.