Funct. Mater. 2026; 33 (2): 168-177.

The study examines the synthesis, structure, and optical properties of lithium tantalate microcrystals impregnated with an aqueous praseodymium nitrate solution and annealed at various temperatures. The samples were characterized by X-ray diffraction, scanning electron microscopy, diffuse reflection, and luminescence spectroscopy. It was found that trigonal LiTaO₃ is the main phase obtained during synthesis. LiTa₃O₈ and Pr₂Ta₂O₉ admixture phases were observed in small amounts at annealing temperatures T ≥ 800 °C. The XRD data indicated that Pr³⁺ ions are incorporated in both Li+ and Ta⁵⁺ cationic positions in LiTaO₃ crystals. SEM data showed that doping and annealing lead to a reduction in the crystallite’s size from about 3–5 µm to 1–4 µm. The estimated band gap values for initial LiTaO₃ and samples synthesized at 600 and 800 °C were 4.67 eV, while corresponding values are about 4.55 eV for samples prepared at higher temperatures. The doped samples revealed intense f-f photoluminescence of Pr3+ ions under their excitation directly via the allowed 4f - 5d transition (250–370 nm) and via parity-forbidden ³H₄ -> ³P_J electric-dipole f-f transitions (440–510 nm). The synthesis temperature and the excitation wavelength significantly influence the color properties of the emission. The calculated correlated color temperatures indicated that all the samples reveal “warm” visible light.