Thermally stimulated luminescence properties of MgTa₂O₆ prepared by solid-state chemical reaction

Persistent luminescent (PLUM) materials have been developed for a variety of applications in road marking, toys decoration, safety and bio-imaging. Such materials are set to answer the need for energy conservation. In this work, Magnesium Tantalate (MgTa₂O₆) compound was synthesized by a conventional solid-state chemical reaction route at 800 °C for 8 h, after ball milling the mixed precursors. The MgTa₂O₆ compound was confirmed with only minor impurities of Ta₂O₅, as identified by X-ray diffraction (XRD). The scanning electron microscopy (SEM) images of MgTa₂O₆ showed a surface morphology with different shapes and sizes, which are bound to each other. The energy band gap of the material was approximated to 4.34 eV using the Kubelka-Munk relation. The photoluminescence (PL) spectrum displayed a broad emission between 360 and 780 nm, when the sample was excited with a 295 nm beam, as observed from the photoluminescence excitation (PLE) spectrum. Upon investigating the thermoluminescence (TL) properties of the compound, the glow curves revealed the presence of at least three prominent electron trapping centres at ∼108, ∼258, and ∼315 °C. The competition between electron trapping centres, pre-heating effects, stability of the electron trapping centres and TL fading were examined. In addition, the depth of the electron trapping centres was determined. From the TL analysis, the prominent electron trapping centres were approximated to 0.75 ± 0.04 eV, 1.28 ± 0.07 and 1.55 ± 0.02 eV. Additionally, from the stable electron trapping centres and TL signal fading study, results indicated that MgTa₂O₆ is a promising material for energy storage applications.