Spectral Investigation of Enhanced Orange Emission in Eu³⁺ Activated LaPO₄ Nanophosphors Through Codoping With Na⁺ and Bi³⁺ Ions

Lanthanum phosphate is a well‐known potential host for rare earth activators for phosphor‐converted white LED application. Na⁺ and Bi³⁺ codoped Eu³⁺ activated LaPO₄ nanophosphor is successfully synthesized using citrate‐based hydrothermal method at ambient condition and confirmed by XRD, EDS and XPS analysis. The excitation spectra of the sample exhibit sharp f‐f characteristics peak of Eu³⁺ at 393 nm that is found to be the most dominant. The comparative photoluminescence studies of La_1‐xPO₄:xEu³⁺(x = 0.10), La_1‐x‐y PO₄:xEu³⁺, yNa⁺(x = 0.10, y = 0.05), and La_{1‐x‐y‐z}PO₄:xEu³⁺, yNa⁺, zBi³⁺ (x = 0.10, y = z = 0.05) reveal a progressive enhancement of the orange emission from Eu³⁺ as Na⁺ and (Na⁺, Bi³⁺) ions are incorporated into the LaPO₄ matrix. The dominance of ⁵D₀‐⁷F₁ magnetic dipole transition contributing a major part of orange luminescence of the nanophosphors and the symmetric site occupancy of Eu³⁺ was justified from the observed trend of in the Judd–Ofelt intensity parameters. The CIE studies confirm the improvement in color purity of emission from 32.5% to 90.6% due to the presence of Na⁺ and Bi³⁺ions.