Novel crystallized aerogels based on Y2O3, Y2O3:Tb3 + , and Tb2O3: Synthesis, structure, morphology, luminescence and porosity properties

Aerogels are renowned for their exceptional thermal and acoustic insulation properties, which arise from their extremely high porosity resulting from a three-dimensional (3D) network of interconnected particles. Despite their well-established applications, aerogels offer a wide range of opportunities for further research and development, particularly through the incorporation of novel compounds such as rare-earth oxides (REOs) to impart additional functionalities, including luminescence. In this study, aerogels of yttrium oxide (Y 2 O 3 ), terbium oxide (Tb 2 O 3 ), and doped compositions (Y 2 O 3 :Tb 3+ at 2, 5, and 8 mol%) thereof were synthesized via the sol–gel process using the nitrate route, followed by supercritical CO 2 drying (scCO 2 ) and subsequently, the materials were heat-treated to induce crystallization. The crystallized aerogels were characterized using infrared spectroscopy (IR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), photoluminescence spectroscopy (PL), and nitrogen adsorption analysis (BET). The materials exhibited, at 800 °C, the characteristic metal–oxygen–metal (M–O–M) bonding of rare-earth oxides, with a vibrational band observed at 565 cm⁻ 1 . Morphological analysis confirmed the highly porous nature of the materials, composed of interconnected particles with appropriate chemical composition and C-type crystalline structures. Finally, photoluminescence analysis of the crystallized aerogels revealed emission bands between 480 and 650 nm, corresponding to the 5 D 4 → 7 F 6–3 electronic transitions of Tb 3+ , resulting in a greenish-yellow luminescence. These materials present strong potential for applications in bioimaging, optical sensing, and theranostic platforms, enabling multifunctional materials for diagnostics, tracking, and targeted biomedical interventions. • The sol–gel process was successfully employed to synthesize crystallized aerogels. • The Y 2 O 3 :Tb 3+ crystallized aerogel exhibited an extremely porous structure. • The Y 2 O 3 :Tb 3+ aerogel exhibited greenish-yellow photoluminescent properties.