2025-09-042025-09-042025TORQUATO, Alisson; SANTANA, Ricardo Costa de; MAIA, Lauro June Queiroz. Development and spectroscopy study of YPO4:Tm3+ nanopowders. Journal of Alloys And Compounds, Amsterdam, v. 1037, e182612, 2025. DOI: 10.1016/j.jallcom.2025.182612. Disponível em: https://www.sciencedirect.com/science/article/pii/S0925838825041738. Acesso em: 3 set. 2025.0925-8388e- 1873-4669https://www.sciencedirect.com/science/article/pii/S0925838825041738The Y1-xTmxPO4 nanopowders were successfully synthesized via the coprecipitation method assisted by slow evaporation under basic conditions (pH = 10), yielding particles with an average length of about 26 nm ± 8 nm observed by Transmission Electron Microscopy images. The diffuse reflectance spectra (DRS) show higher reflectance of powdered samples in the visible range, and optical bandgaps (Eg) values were obtained using the Kubelka-Munk approach, which ranged from 4.5 to 4.7 eV, indicating an insulator nature. The powders displayed remarkably intense blue emission centred at 452 nm, originating from the 1D2 → 3H6 transition under 361.5 nm excitation. This emission was accompanied by a residual contribution from a near-infrared emission band at approximately 783 nm, which was attributed to the 1G4 → 3H5 and 3H4 → 3H6 transitions due to residual multiphonon decay and cross-relaxation mechanisms, respectively. The lifetimes of the 1D2 state range from 42 to 35 µs, displaying monoexponential behaviour as the concentration rises from 0.25 % mol to 2 % mol. The dipole-dipole interaction between ions is confirmed for blue emission using the Dexter model, which has a critical distance of ∼ 24 Å. The same behaviour is also observed for the lifetimes from the 1G4 state, decreasing from 422 µs (0.25 mol. %) to 170 µs (2 mol. %), with a bi-exponential behaviour due to the more effective cross-relaxation mechanisms. The relative changes between 1D2 and 1G4 energy levels allow for tuning the emission colour from blue to cyan by adjusting the delay time. Additionally, the CIE chromaticity coordinates of steady-state PL spectra indicate that the samples have a colour purity of above 93 % for x > 0.01 in the deep blue region, indicating the Y1-xTmxPO4 nanopowders as a versatile blue to cyan emitter component for W-LED applications.engAcesso RestritoOrthophosphateLifetimeThuliumBlue phosphorCross-relaxationArtigo10.1016/j.jallcom.2025.182612