Orange emitting BaY2O4: Sm3+ nanopowders: Optical and electrochemical evaluation for display device and supercapacitor applications

In recent years, nanoscale materials have attracted considerable attention owing to their superior optical properties compared to their bulk materials. In this report, using nitrates of metals as oxidizing agents and neem leaves extraction as a bio-based fuel, samarium (Sm 3 + )-doped barium yttrium oxide NPs have been prepared using the combustion synthesis method. This leads to a strong exothermic redox reaction, resulting in the formation of crystalline and pure-phase samarium doped-barium yttrium oxide (BaY₂O₄: Sm³⁺) NPs. The PXRD confirmed the formation of an orthorhombic BaY₂O₄ phase consistent with JCPDS Card No. 27–0044. Analysis of the DRS spectra using the Kubelka–Munk function indicated that the band gap energies of the prepared samples varied from 3.68 to 4.36 eV. FESEM micrographs revealed a porous, sponge-like structure. TEM analysis confirmed the quasi-spherical nanostructures with an average dimension of 42 nm and interplanar spacing-d around 0.28 nm. The photoluminescence properties of the synthesized nanoparticles were investigated using excitation and emission spectroscopy. Three strong Sm 3+ ions transitions, 4 G 5/2 → 6 H 5/2 (yellow), 4 G 5/2 → 6 H 7/2 (orange-red) and 4 G 5/2 → 6 H 9/2 (red) are located at 564, 606 and 648 nm were observed under excitation wavelength 466 nm. Among these transitions, sharp emission peak located at 606 nm indicated orange red emission. These results highlight BaY₂O₄: Sm 3+ nanophosphors as promising multifunctional materials for integrated application in solid-state lighting mainly for fabricating white LEDs. In addition to its superior luminescence performance for display applications, the synthesized phosphor exhibits promising electrochemical behavior, suggesting its potential as a multifunctional material for supercapacitor applications.