Band-Gap Engineering of High-Entropy Fluorite Metal Oxide Nanoparticles Facilitated by Pr3+ Incorporation by Gel Combustion Synthesis

Gels. 2025. Vol. 11. No. 2. Article 117.

Anandkumar M., Kesavan K. P., Sudarsan S., Zaitseva O. V., Ostovari Moghaddam A., Iarushina D. V., Трофимов Э.

Tailoring the bandgap of a material is necessary for improving its optical properties. Here, the optical bandgap of high-entropy oxide Ce0.2Gd0.2Sm0.2Y0.2Zr0.2O2-δ (HEO) nanoparticles was modified using Pr3+. Various concentrations of Pr3+ (x = 0, 0.01, 0.02, 0.05, 0.075, 0.1, 0.15) were incorporated into the host high-entropy oxide using a gel combustion synthesis. After the gel combustion step, the powders were heat-treated at various temper-
atures (650 ◦C, 800 ◦C, 950 ◦C) for 2 h. The obtained Pr3+-incorporated HEO powders were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV–visible spectroscopy. The results indicate that, when the samples are calcined at 950 ◦C, a single-phase cubic fluorite structure is obtained without any phase separation or impurity. The optical absorbance red-shifts to higher wavelengths when the
concentration of Pr3+ is increased. This reduces the bandgap of the material from 3.15 eV to 1.87 eV for Pr3+ concentrations of x = 0 (HEO-0) and x = 0.15 (HEO-6), respectively. The obtained HEOs can be suitable candidates for photocatalytic applications due to their absorbance in the visible region.

Keywords: поглощение, твердый раствор, band gap, Solid solution, High-entropy oxides, Высокоэнтропийный оксид, gel combustion, absorbance, fluorite oxide, горение геля, запрещенная зона, оксид флюорита

Publication based on the results of: Advanced materials and technologies (2025)