Judd–Ofelt analysis and luminescence studies of Eu3+: La(OH)3 nanophosphors synthesized via microwave enabled co-precipitation

An investigation on the structural and photoluminescent properties of La(OH)₃:xEu³⁺ phosphors synthesized by microwave assisted co-precipitation method and the evaluation of spectroscopic parameters has been reported. Structural, morphological, and optical studies were conducted using XRD, FTIR, SEM, EDAX, TEM and photoluminescence analysis. The samples annealed at 700 °C were crystallized into hexagonal phase, devoid of any impurities. Emission spectra reveal characteristic Eu³⁺ emission peaks with predominance in the red spectral region, displaying CIE colour coordinates close to commercially available red phosphors. The spectroscopic properties of the prepared phosphor material were investigated in detail on the basis of Judd-Ofelt analysis. The observed trend of Ω₂ > Ω₄ (JO intensity parameters) aligns with the higher intensity of ⁵D₀→⁷F₂ electric dipole transition in the emission spectra and hence confirms asymmetric site occupancy of Eu³⁺ ions in the host matrix. The relatively high values of radiative parameters (derived from JO intensity parameters) - especially branching ratio, stimulated emission cross-section and gain bandwidth for major Eu³⁺ transitions substantiate the applicability of europium doped lanthanum hydroxide nanophosphors in solid state lighting, lasing, optical amplifiers, etc. Thus, the study confirms the potential and relevance of prepared phosphor as a promising candidate for NUV/UV excited red emitter for lighting and display applications.