The down-conversion process requires that the cerium ions are in the Ce3+ state and are associated with oxygen vacancies, which implies that ceria nanoparticles contain Ce2O3 is a direct semiconductor [11]. To obtain visible light via up-conversion, ceria nanoparticles must be doped with certain lanthanides, such as erbium, then annealed at temperatures above 700°C [12]. Ceria is a low-phonon host for the erbium ions, which act as optical centers that convert the energy from absorbed IR photons into

visible light [13]. Linsitinib concentration However, the presence of the negative-association energy element, erbium, and the high temperature anneal causes the dominant ionization state of cerium ions to be in the Ce4+ state where Ce4+ ions bond with oxygen to

form CeO2, an indirect semiconductor [10, 14, 15]. Hence, the down-conversion emission efficiency of the erbium-doped ceria nanoparticles (EDC NPs), particularly after the thermal anneal, is low [10]. On the other hand, there is no observable up-conversion emission from undoped ceria nanoparticles or from ceria nanoparticles doped with positive association energy lanthanide. Thus, to optimize the properties of ceria nanoparticles for the two optical conversion processes, it has been required two different nanoparticle synthesis and post-processing procedures. As shown in the illustrative Osimertinib research buy diagram of Figure 1, this work introduces a reduced EDC NPs that have the unique material properties to act as an optical medium for both down-conversion and up-conversion in the same time to generate multi-wavelength from visible emissions under near this website UV and IR excitations, respectively. The used synthesis process results in a high concentration of Ce3+ ions associated with the oxygen vacancies in ceria, which is required to obtain high fluorescence efficiency in the down-conversion process. Simultaneously, the synthesized nanoparticles contain the molecular energy levels of erbium that are required for up-conversion. Therefore, the EDC NPs synthesized using this procedure can emit visible light when excited with either or both UV or IR photons. This work is the first, to the best of the authors’

knowledge, to offer one optical nanomaterial for both up- and down-conversions simultaneously. This opens new opportunities for applications where emission of visible light via both up- and down-conversions from a single nanomaterial is desired. Figure 1 Illustrative diagram demonstrating usage of EDC NPs in generating visible light. Simultaneous UV (down-conversion) and IR (up-conversion) excitations. Methods EDC NPs are prepared using the chemical precipitation technique which is relatively simple and inexpensive synthesis process [16, 17]. Cerium (III) chloride (0.475 g) and erbium (III) chloride (0.025 g) are dissolved in de-ionized (DI) water (40 mL) to obtain a 5% weigh ratio of erbium to cerium in the synthesized nanoparticles.