Salvador Carmona TélLez

This study details the synthesis of YVO₄:Eu³⁺ phosphor and three distinct phosphor-in-glass (PiG) composites, which were developed using borosilicate (by Corning), Gorilla^® Glass, and boron-calcium invert glass matrices. Analysis of luminescence characteristics reveals that the phosphor follows the expected transitions of the Eu³⁺ ion, producing a high purity red emission, centered at 619 nm. Its emission spectrum consists of four primary bands located at 595, 619, 652, and 700 nm, due to the ⁵D₀ energy level to the ⁷F_J (J = 1, 2, 3, or 4) Eu³⁺ states. PiGs maintain chromatic purity while offering significantly enhanced luminescent intensity and quantum yield compared to YVO₄:Eu³⁺ phosphor. This performance is attributed to a combination of factors, including the intrinsic improvement in the crystallinity of the phosphor upon the 800 °C treatment and the protective role of the glass matrix. Additionally, the partial migration of Eu³⁺ ions to sites within the glass network may contribute to more efficient light emission. Many phosphor/glass ratios were tested, finding that 60% phosphor and 40% glass maximized luminescent output across all glass systems, while over 60% phosphor resulted in a clear loss of structural integrity producing fragile materials, establishing this ratio as the functional limit. Ultimately, the data indicate that the improvement in the final optical performance of PiG systems is fundamentally dictated by the specific chemical environment and nature of the glass host utilized in the synthesis.

Synthesis and characterization of calcium-based materials (CBMs) such as calcium pyrophosphate and hydroxyapatite activated with Er(III)–Yb(III) and Eu(III), respectively, are reported to establish their utility as markers for dosimetry and biological imaging. Under 980 and 246 nm excitation, these phosphors produce distinct emissions through 2H11/2 to 4I15/2 and 5D0 to 7F4 Er(III) and Eu(III) transitions, respectively. Despite the promising optical performance of these materials, there is a notable lack of toxicological data regarding lanthanides such as Er(III), Yb(III), and Eu(III) when utilized as dopants. To address this knowledge gap, a chronic toxicity study was performed by using the Daphnia magna model at 300 mg/L. The results indicate that although CBMs do not cause significant mortality, they can produce significant physiological changes, such as delaying sexual maturity from 9.6 to 13 days and reducing the number of neonates per female (around 50%) in the Eu(III)-doped samples (the most critical case). Survival rates also showed a decrease, from 95% to near 70%, in doped hydroxyapatite. These findings suggest that CBMs are suitable for biomedical applications because they cannot produce either highly toxic or fatal effects at these levels. Nevertheless, their eventual implementation could require careful concentration management to protect the organism’s suitability. This work provides an assessment of the environmental impact of these dopants and supports their responsible integration into future device development and diagnostic biological imaging applications.

The synthesis and characterization of gadolinium-based micro- and nanophosphors are reported. These materials were synthesized by solvent evaporation technique and microwave-assisted solvothermal method, respectively. According to scanning electron microscopy measurements, Gd₂O₃ and Gd(OH)₃ phosphors have lamellar and nanorods structures, respectively. Their luminescent properties are generated by the presence of Tb^3  + ions, which produced light emission at 484, 542, 583, and 621 nm due to the D₄5 → F₆7, F₅7, F₄7, and F₃7 interlevel transitions within Tb^3  + electronic energy states. These phosphors were embedded into two polymers, polymethyl methacrylate and polystyrene, and their luminescent properties were transferred to polymeric films. In addition, in this case, films can be activated under lower excitation energy than powder phosphors because an energy transfer from polymers to Tb^3  + ions exists. The obtained results reveal that gadolinium-based micro- and nanophosphors are candidates for manufacturing luminescent materials in industrial and biological applications as well.

ZrO₂ and ZrO₂: Al³⁺(× at.%) films were deposited by ultrasonic spray pyrolysis process. Luminescent films were produced from Oxychloride Zirconium Octahydrate and Aluminium Chloride Hexahydrate as precursors. Measurements of photo and cathodoluminescence were carried out doing variations on deposition temperature and doping concentration (× at.% Al³⁺ions). With the increase in substrate temperature, an overall growth of photo-cathodoluminescence intensities was perceived. Furthermore, these films presented luminescence concentration quenching with hight Al doping concentration. Chromaticity coordinates indicated blue emission from host lattice (ZrO₂ films) and cold-white emissions from ZrO₂: Al³⁺(× at.%) films. Closest CIE coordinates to the perfect white emission were x = 0.303, y = 0.337. XRD patterns, measured with variations of substrate temperature, showed tetragonal phase of nano-zirconium oxide films. In addition, surface morphology characteristics for studied films are presented.