Effect of Doping Concentration on the Luminescence Properties of MoO₃: Tb³⁺ Nanobelts

The development of rare-earth-doped oxide nanomaterials has garnered significant interest due to their potential applications in display and biomedical imaging technologies. Among them, MoO₃, with its favourable optical properties, emerges as a promising host material for nanophosphors. In this work, the hydrothermal method was employed to synthesise MoO₃: Tb³⁺ nanobelts by varying the terbium concentration. Structural, optical, morphological and photoluminescence characteristics were systematically examined. FESEM and TEM revealed nanobelt morphology. XPS verified the successful incorporation of Tb³⁺ ions. A thorough study of the photoluminescence mechanism, including concentration quenching and lifetime measurements, was carried out, as these aspects are still not well studied for this material. Under 260 nm excitation, blue-green emission was observed with optimal photoluminescence intensity at 2 mol% Tb³⁺ doping. The optimised sample was annealed at 500°C for 12 h, resulting in greenish-white emission. Emission colour coordinates were determined using the CIE chromaticity diagram, and a dipole-dipole interaction mechanism with a critical distance of 17 Å was identified as the cause of quenching. The average photoluminescence lifetime of the annealed sample was ~1.1 μs. These results demonstrate the potential of MoO₃: Tb³⁺ nanobelts as efficient phosphor materials for next-generation display and bioimaging applications.