Electron Beam-assisted Synthesists, Structure and Luminescent Properties Porous Ceramics of MgAl2O4 and MgAlGaO4 Doped with Europium

Abstract

Porous ceramics of MgAl₂O₄ (MAS) and MgAlGaO₄ (MAGS) doped with europium were synthesized by ra- diation method. Radiation synthesis was performed with high efficiency within less than 1 s using radiation energy and mixture materials with no additives or any other materials used to promote synthesis. The synthe- sis method using a high-energy electron beam makes it possible to obtain refractory materials with high productivity, flexibly control the technological conditions of the process, and, accordingly, synthesize materi- als with desired properties. The structural properties of synthesized porous ceramics were investigated by X- ray diffraction (XRD-7000S diffractometer, Shimadzu), SEM. Results have shown that, the synthesized MAS have cubic structure and are in crystalline spinel MgAl₂O₄, while the synthesized double spinel MAGS con- tains two main phase components, MgAl₂O₄ and MgGa₂O₄. To study the luminescence properties of MAS and MAGS synthesized spinel doped with europium, photoluminescence measurements were performed. The photoluminescence spectrum of excitation of Eu³⁺ ions in spinel was monitored at λ_em = 615 nm (⁵D₀→⁷F₂). The PLE shows the f→f transition in the configuration of Eu³⁺ ions (at 393 nm (⁷F₀→⁵L₆), 463 nm (⁷F₀→⁵D₂)). The excitation band at 330 nm and 260 nm is characteristic of the charge transition between Eu³⁺ and O^2- ions. The photoluminescence spectrum of the samples under excitation at 260 nm was studied. In the PL spectrum of spinel samples, the emission of Eu³⁺ ions are clearly visible. In the structure of the band with a maximum of 615, a peak is visible at 590 nm, characterized by the ⁵D₀ → ⁷F₁ transition. In the PL spectrum of samples, a weak spectral band appears with a maximum at 535 nm, characteristic of the emission of Eu³⁺ ions with the ⁵D₁-⁷F₁ transition. It is shown that the efficiency of radiation synthesis depends on the granulometric composition of the initial oxide powders.