UV-shielding property, photocatalytic activity and cytotoxicity (including photocytotoxicity) of citrate-stabilized ceria colloid solutions were studied. It was established that UV-shielding property (namely, the sun protection factor, the critical absorption wavelength and the UVA/UVB-ratio) of ceria nanoparticles are as good as those of titanium dioxide and zinc oxide nanoparticles. It was further demonstrated that ceria nanoparticles possesses substantially lower photocatalytic activity, which additionally decreases upon decrease in ceria particle size. It was found that colloid ceria solutions are non-toxic to mouse fibroblasts (L929) and fibroblast-like cells of African Green monkey (VERO). Moreover, ceria nanoparticles are capable to protect these cells from UV-irradiation-induced damage. It was proposed that nanocrystalline ceria could be used not only as UV-blocking material, but also as prophylactic and even therapeutic compound for sunburns treatment.

A new microwave-hydrothermal process has been developed for preparing stable aqueous sols of nanocrystalline ceria. Transmission electron microscopy, UV-Vis spectroscopy, and dynamic light scattering shows that CeO2 nanoparticle size remains unchanged during hydrothermal treatments. Sodium adenosine triphosphate and sodium citrate are proposed for additional stabilization of the sols.

Предложены новые методы получения водных золей нанокристаллического диоксида церия, стабилизированных лимонной и полиакриловой кислотами. Методами просвечивающей электронной микроскопии и УФ-видимой спектроскопии исследована устойчивость золей к гидротермальной обработке в диапазоне температур 120–210°С.

The growth of ceria nanoparticles during annealing at high temperatures (up to 700°C) has been studied by X-ray diffraction, transmission electron microscopy, and low-temperature nitrogen adsorption measurements. The results indicate that CeO 2 nanopowders prepared using freeze drying offer enhanced thermal stability.

Correlation relations between oxygen nonstoichiometry and particle size in nanocrystalline CeO 2 − x are revised. The ceria unit cell parameter is shown to increase from 0.5410 to 0.5453 nm as the particle size decreases from 23 to 2.3 nm. The CeO 2 − x critical particle size where cerium(IV) is completely reduced to cerium(III) is calculated as 1.1–1.3 nm.

New methods are proposed for preparing aqueous sols of nanocrystalline ceria stabilized by citric or polyacrylic acid. Transmission electron microscopy and UV-Vis spectroscopy were used to study the stability of sols in hydrothermal treatment at temperatures in the range of 120–210°C.

Directed search for further manifestations of size-dependent effects in the functional properties of nanomaterials constitutes a key line of nanotechnologies research. The major size-dependent effects were analyzed for nanocrystalline ceria. The practically significant techniques for preparation of ceria nanopowders with controllable micromorphology were analyzed. Selected promising applications of this material were described.

The specifics of electrochemical lithium intercalation into nanocrystalline ceria were studied. The lithium capacity of CeO2 − x is discovered to increase systematically as the nanoparticle size shifts down, indicating the potential of nanocrystalline ceria for use in electrochromic applications.

The mesostructure of amorphous xerogels based on hydrated zirconia ZrO(2) and its evolution at different stages of heat treatment have been investigated using the small-angle neutron scattering method. A correlation function of the nuclear scattering amplitude density has been obtained from experimental neutron scattering cross sections, and the characteristic radii of ZrO(2) nanoparticles and their specific surface areas have been determined. The influence of the annealing temperature on the fractal properties of the zirconia surface has been elucidated.

Particle coarsening trends at high temperatures (200 to 700 °C) in CeO2 nanoparticles having various chemical histories are determined by powder X-ray diffraction (XRD), low-temperature nitrogen adsorption, transmission electron microscopy, and small-angle neutron scattering (SANS). Intergrowth of individual CeO2 crystallites is the main scenario of nanoparticle coarsening.

Уточнена зависимость кислородной нестехиометрии нанокристаллического CeO2 - x от размера частиц. Показано, что при уменьшении размера частиц от 23 до 2.3 нм значения параметра элементарной ячейки диоксида церия возрастают от 0.5410 до 0.5453 нм. Рассчитан критический размер частиц CeO2 - x (1.1–1.3 нм), при котором происходит полное восстановление Ce(IV) до Ce(III).