Synthesis and Structural Features of Tunable Emitting Single-Phased Eu3+/Tb3+ Co-Doped LaAlO3 Nanophosphors

Abstract

In the prevailing study, single-phased color-tunable La_1–x–yEu_xTb_yAlO₃ co-doped nanocrystalline phosphors have been synthesized via the most simplistic and low-cost urea-aided solution combustion synthetic route. This was done by adjusting the doping concentration of Eu³⁺ (x = 0.01 mol, 0.03 mol, 0.05 mol, 0.07 mol) and Tb³⁺ (y = 0.03 mol) ions in the LaAlO₃ host lattice. The X-ray powder diffraction (XRD) and Rietveld refinement analysis confirmed the formation of single-phased La_0.97–xAlO₃:xEu³⁺/0.03Tb³⁺ (x = 0.07), co-doped nanophosphor at 800 °C. The synthesized nanophosphors were crystallized in cubic crystal system having \(Pm\overline{3}m\) space group with 221 space group number. The morphological studies, i.e. field emission scanning electron microscopy (FE-SEM), and transmission electron microscope (TEM) images depicted the agglomerated clusters of distinct spherical shaped particles of La_0.97–xAlO₃:xEu³⁺/0.03Tb³⁺ in nano-regime. Energy dispersive X-ray analysis (EDAX) was employed to ascertain the real elemental mapping of the fabricated phosphors. Through diffuse reflectance (DR) spectroscopy measurements, the optical band gap value for La_0.92Eu_0.05Tb_0.03AlO₃ nanocrystalline phosphor was determined to be 5.26 eV. The photoluminescent excitation (PLE) and photoluminescent emission (PL) spectra were studied in detail as a function of Eu³⁺ ion contents and La_1–x–0.03AlO₃:xEu³⁺/0.03Tb³⁺ (x = 0.05 mol) co-doped sample exhibits strongest emission and over the 0.05 Eu³⁺ ions doping concentration, the emission intensity falls as a consequence of the quenching phenomenon. The concentration quenching in directed co-doped nanophosphors was attributed to the dipole-dipole interactions. With the exploitation of photoluminescent data, Commission International de I′Eclairage 1931 (CIE) color coordinates (x, y) of co-doped samples have been calculated from the emission spectra, which revealed the color could be tuned i.e., from orange to red region in La_0.97–xAlO₃:xEu³⁺/0.03Tb³⁺ samples with divergences in the Eu³⁺ and other significant photometric assets viz. correlated color temperature (CCT), color purity (CP) of the synthesized La_1–x–yAlO₃:xEu³⁺, yTb³⁺ co-doped nanocrystalline photoluminescent materials were also determined. The studies outcomes suggested that Eu³⁺/Tb³⁺ co-doped LaAlO₃ phosphors have great potential as color-tunable luminescent material in solid-state lighting and display technologies.