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Observing capacitive behavior in an OCP material is quite exciting and may enable or enhance future medical applications, such as biocompatible energy storage and harvesting microdevices.

Synthesis of nanocrystalline, spherical, and anatase type TiO2 photocatalyst were performed by supercritical gas antisolvent process in the range of 50150 • C and 100150 bar. As-prepared samples were calcined at 500 • C and characterized by X-ray diraction, scanning electron microscopy, BrunauerEmmettTeller method, dierential thermal analysis/thermal gravimetry. In X-ray diraction analysis, the anatase crystalline phase of titanium dioxide has been detected. The mean crystalline size of powders is about 13 nm. The photoactivity test of the powders was evaluated by the photodegradation of aqueous RR 180 (reactive red 180) solution under UV light. While the photocatalytic performance of TiO2 powders (BrunauerEmmettTeller surface area of 69.2 m 2 /g) produced at 150 bar and 150 • C was found to be 98%, only 25% degradation was observed with powder produced at 150 bar and 100 • C. Results showed that the powder properties and photocatalytic activity can be tuned by controlling the supercritical conditions such as temperature and pressure.

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The citrate gel method, similar to the polymerized complex method, was used to synthesize homogeneous tetragonal zirconia at 1000• C. Nanocrystalline tetragonal phase has been fully stabilized at wide temperature range with 10 mol.% CaO, MgO, and Y2O3 addition. Scanning electron microscopy, X-ray diraction, and microhardness tests are used to characterize synthesized materials. The grain size and dislocation density were calculated from X-ray diraction data. The examined material exhibits indentation size eect behavior. Results revealed that the Vickers and Knoop microhardness are dependent on indentation test load. Geometrically necessary dislocation model and modied proportional resistance model are used to analyze the load dependence of the microhardness. The highest hardness values were obtained for the samples with CaO addition; however the lowest values were acquired for sample stabilized with Y2O3 by using both Knoop and Vickers techniques. This situation might be explained using the HallPetch relation.