The antioxidant efficacy of CeO(2) nanoparticles can be enhanced by dissolving zirconium in the CeO(2) lattice. The Ce(x)Zr(1-x)O(2) nanoparticles act as an enhanced catalyst at room temperature that scavenges ROS. Increased efficacy will enable lower nanoparticle dosages to protect cells from ROS, thus increasing the therapeutic width of these compounds.

The growth characteristics of u-Al 2 O 3 crystallites in u-Al 2 O 3 powder systems with sizes \25 nm were examined. Two u-Al 2 O 3 powders, with mean particle sizes of 12.0 and 20.4 nm, and their mixtures at various weight ratios were homogenized and fabricated into compacts, representing powder systems with various mean sizes and packing densities. The growth characteristics of these powder systems were then examined in the compacts using X-ray diffracion, transmission electron microscopy, differential thermal analysis, and Brunauer-Emmett-Teller adsorption techniques. It was found that the u-Al 2 O 3 crystallites in the powder system were coarsened by the coalescence of u-crystallites of similar sizes. Powder systems, even with different mean sizes, exhibited similar growth rates that could be expressed by the reduction of their surface area per unit volume per time. The smaller crystallites initiated growth by coalescence at lower temperatures, while the larger crystallites maintained their sizes until the smaller ones reached their size; then, both grew simultaneously. Thus, it is possible for a powder system ultimately to develop u-crystallites of similar size that lead to a simultaneous u-to-a-Al 2 O 3 phase transformation during thermal treatment. The increase in the packing density of the powder systems caused u-crystallite growth to begin at lower temperatures.

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The growth thermodynamics of nanoscaled α-Al2O3 crystallites after its formation from θ-Al2O3 phase transition by thermal treatment was examined. The crystallite growth characterized with quantized size increments can be performed through coalescence processes. The α-Al2O3 nuclei with sizes 17−20 nm (d cα) coalesced to form α-crystallites of sizes 45−50 nm (d p), then by coalescence of which the stable α-crystallites (d s) with minimum sizes 75−80 nm were obtained. Coalescence of the d s crystallites leads to formation of the crystallites with vermicular growth. A growth thermodynamic model describing the three-staged size growth was proposed. It provides well-coincided calculations with the data observed. The surface free energy of θ-Al2O3, which is being reported for the first time, is 2.16 J/m2.