Green emission from trivalent cerium doped LaAlO3/MgO nano-composite for photonic and latent finger printing applications

Abstract

A series of Ce³⁺ doped La_1−xCe_xAlO₃/MgO (x = 0, 0.7, 0.9, 1.0 and 2.0 mol%) nano-composites have successfully been synthesized employing the Pechini sol–gel method. XRD profiles assisted with Rietveld refinement results manifested the rhombohedral/face-centered structures of the two phases of the generated composite. Thermogravimetric results corroborate the crystallization temperature of the compound to be 900 °C, that further remains stable up to 1200 °C. Materials have been found to be wide band gap semi-conductors having E_g in the range of 5.5–5.8 eV. Photoluminescence studies reveal their green emission under UV excitation of 272 nm. Application of Dexter's theory and Burshtein model to PL and TRPL profiles, respectively reveals the q–q multipole interlinkages to be the viable cause of concentration quenching beyond optimum concentration of 0.9 mol%. Shifting of the energy transfer route from cross-relaxation to migration assisted mechanism with Ce³⁺ concentration has also been investigated. Other luminescence based parameters such as energy transfer probabilities, efficiencies, CIE and CCT have also been found to be in an admirable range. From the aforesaid results, it was observed that the optimized nano-composite (i.e. La_1−xCe_xAlO₃/MgO (x = 0.9 mol%)) can also be utilized for latent finger-printing (LFP) application that evinces its versatility for photonic as well as imaging applications.