Photoluminescence, photocatalysis and Judd–Ofelt analysis of Eu3+-activated layered BiOCl phosphors

Abstract

Eu³⁺-activated layered BiOCl phosphors were synthesized by the conventional solid-state method at relatively low temperature and shorter duration (400 °C for 1 h). All the samples were crystallized in the tetragonal structure with the space group P4/nmm (no. 129). Field emission scanning electron microscopy (FE-SEM) studies confirmed the plate-like morphology. Photoluminescence spectra exhibit characteristic luminescent ⁵D₀ → ⁷F_J (J = 0–4) intra-4f shell Eu³⁺ ion transitions. The electric dipole transition located at 620 nm (⁵D₀ → ⁷F₂) was stronger than the magnetic dipole transition located at 594 nm (⁵D₀ → ⁷F₁). The evaluated Commission International de l'Eclairage (CIE) color coordinates of Eu³⁺-activated BiOCl phosphors were close to the commercial Y₂O₃:Eu³⁺ and Y₂O₂S:Eu³⁺ red phosphors. Intensity parameters (Ω₂, Ω₄) and various radiative properties such as transition probability (A_tot), radiative lifetime (τ_rad), stimulated emission cross-section (σ_e), gain bandwidth (σ_e × Δλ_eff) and optical gain (σ_e × τ_rad) were calculated using the Judd–Ofelt theory. The experimental decay curves of the ⁵D₀ level in Eu³⁺-activated BiOCl have a single exponential profile. In comparison with other Eu³⁺ doped materials, Eu³⁺-activated BiOCl phosphors have a long lifetime (τ_exp), low non-radiative relaxation rate (W_NR), high quantum efficiency (η) and better optical gain (σ_e × τ_rad). The determined radiative properties revealed the usefulness of Eu³⁺-activated BiOCl in developing red lasers as well as optical display devices. Further, these samples showed efficient photocatalytic activity for the degradation of rhodamine B (RhB) dye under visible light irradiation. These photocatalysts are useful for the removal of toxic and non-biodegradable organic pollutants in water.