Spectroscopic properties of red-emitting Sr0.9Na0.2ZrO3:Eu3+ phosphors with potential applications in lasers and LEDs

A range of Sr0.9-yNa0.2ZrO3: Eu3+ (SNEZ) nanocrystalline phosphors with high color purity and exceptional laser properties were synthesized using sol-gel technique. The samples were characterized for structural and spectroscopic properties using methods including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), diffuse reflectance spectroscopy, and photoluminescence (PL) spectroscopy. Structural analysis revealed orthorhombic phase with average crystallite size 28-19 nm, decreasing with increasing Eu3+ concentration. A low phonon energy of 455-495 cm(-1) and wide (expanding) band gaps (5.0-5.3 eV) were obtained for the SNEZ phosphors. Under the excitation of 300 nm, the SNEZ phosphor emits strong red light at 614 nm, attributed to the D-5(0) -> F-7(2) transition of the Eu3+ ion. Both XRD and Judd-Ofelt analysis revealed two sites for the Eu3+ ions. Additionally, the optimized SNEZ-7 phosphor achieves a PL internal quantum efficiency of 96 % under UV light at 300 nm excitation. Laser properties such as stimulated emission cross-section, gain bandwidth, branching ratio of the SNEZ phosphor is comparable to those of glasses, fluorides and other oxides for red light emitting laser applications. The CIE coordinate values of the synthesized red phosphor closely match those of commercially available red light-emitting phosphors, with a purity level of about 95 %. This suggests its suitability for various device applications, particularly in high-power white LEDs and lasers, as a red emitter.