Iridium oxohydroxide thin coatings have been prepared by a dynamic oxidation electrodeposition method from complex oxalate solutions that induce template effects in the final coating at the nanoscale. The preparation method induces the formation of a oxohydroxide with reproducible stoichiometry and sponge-like quasiamorphous open structure, high ionic mobility, and significant behavior as compared with other reported iridium oxides as derived from X-ray diffraction, XPS, and TGA. Reproducible mixed valence states are also observed and a local rutile structure that allows ion exchange and facile redox changes. Rather significant is the large affinity for organic compounds observed and the behavior as substrate for cell culture, the best observed to date. Optimal cell response seems to be related to such open structure, which suggests this coating as ideal for devices implanted in the nervous system.

A Mn valence instability on La 2/3 Ca 1/3 MnO 3 thin films, grown on LaAlO 3 ͑001͒ substrates is observed by x-ray absorption spectroscopy at the Mn L-edge and O K-edge. As-grown samples, in situ annealed at 800°C in oxygen, exhibit a Curie temperature well below that of the bulk material. Upon air exposure a reduction of the saturation magnetization, M S , of the films is detected. Simultaneously a Mn 2+ spectral signature develops, in addition to the expected Mn 3+ and Mn 4+ contributions, which increases with time. The similarity of the spectral results obtained by total electron yield and fluorescence yield spectroscopy indicates that the location of the Mn valence anomalies is not confined to a narrow surface region of the film, but can extend throughout the whole thickness of the sample. High temperature annealing at 1000°C in air, immediately after growth, improves the magnetic and transport properties of such films towards the bulk values and the Mn 2+ signature in the spectra does not appear. The Mn valence is then stable even to prolonged air exposure. We propose a mechanism for the Mn 2+ ions formation and discuss the importance of these observations with respect to previous findings and production of thin films devices.

We report the development of a Si-based micro thermogenerator build from silicon-oninsulator by using standard CMOS processing. Ultrathin layers of Si, 100 nm in thickness, with embedded n and p-type doped regions electrically connected in series and thermally in parallel, are the active elements of the thermoelectric device that generate the thermopower under various thermal gradients. This proof-of-concept device produces an output power density of 4.5 µW/cm 2 under a temperature difference of 5 K across the hot and cold regions.