Synthesis and photoluminescence properties of nanoporous anodic aluminum oxide (NAAO): Sm3+ nanocomposite layer: Effect of anodizing parameters (time and voltage), Sm3+ concentrations, and annealing temperatures

Abstract In the present work, nanoporous anodic aluminum oxide (NAAO) layers were synthesized by mild and mild-hard anodization methods in a solution of oxalic acid and photoluminescence properties of these oxide layers were compared. Then, the nanoporous anodic aluminum oxide: Sm3+ (NAAO: Sm3+) nanocomposite layer is produced by boiling the NAAO layers in a solution of samarium nitrate and annealing at different temperatures under argon atmosphere. Moreover, effect of anodizing parameters (time and voltage), Sm3+ concentrations, and annealing temperatures on photoluminescence properties of the NAAO: Sm3+ nanocomposite layers were investigated and results indicate composition of SmAlO3. Finally, morphology, phase structure, energy levels, and emission wavelengths of the oxide layers were investigated by field emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD), and photoluminescence (PL) spectroscopy. Results indicate that the PL intensity of the NAAO layers produced by mild-hard anodization is more than the mild anodization. Moreover, the layers produced at 120 V for 2 h have the most PL intensity. At 1200 °C temperature, 0.7 M concentration of samarium ions the most PL intensity is created. Moreover, with the excitation of the NAAO: Sm3+ nanocomposite layer created at 400 nm wavelength, three main emission bands from the 4f-4f intra-configuration transitions from Sm3+ ions are clearly observed. These transitions include 4G5/2 → 6H5/2, 4G5 2 → 6H7/2, and 4G5/2 → 6H9/2.