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Abstract: The NdCoO3 perovskite has been investigated using a combination of atomistic simulation and experimental techniques to examine its possible use as an oxidation catalyst and/or sensor material. The sensing properties of NdCoO3 and Nd0.8Sr0.2CoO3 towards CO have been investigated by employing thin films deposited by means of radio-frequency (RF) magnetron sputtering onto polycrystalline Al2O3. The response of the films was monitored by performing four-probe DC-conductivity measurements. The conductivity variation induced by switching between a CO-free atmosphere (air) and a CO-rich one with the same composition of residual gas was recorded and analysed as a function of temperature; results are compared for the two samples. Simulation studies focussed on the dopant, transport and redox properties of the pure material; the results indicate that Sr and Ca on the Nd site are the most soluble dopants and that when divalent dopants are incorporated in the structure, charge compensation occurs via oxygen ion vacancies. The low activation energy for oxygen vacancy migration suggests high oxide-ion mobility through the lattice. Particular attention is paid to the electronic processes because of their importance with respect to practical applications of the material. [Copyright &y& Elsevier]

Abstract: In this paper the preparation of neodymium cobaltite (NdCoO3) thin films by means of rf-magnetron sputtering is presented. The sensing properties towards the CO were analyzed by following the resistivity response when changing the gas composition from air to air with CO. Measurements have shown a good response in the temperature range between 250 and 400°C for CO concentration until 1000ppm. Measurable resistance changes are accomplished within few minutes after gas switch. The optimal working temperature was found to be around 300°C by taking into account the amount of resistance variation and the time required to achieve an easily measurable response for different temperatures and CO concentrations. In order to explain the results obtained, a possible model for the NCO response mechanism towards CO is presented. [Copyright &y& Elsevier]

Abstract: Mn-K edge EXAFS and XANES spectra of La0.87Na0.13MnO3 manganite films with different thicknesses (750, 250, 125 and 50Å), have been acquired at RT. In the 50Å film a shift of the Fermi level downward in energy is found if compared to the other films. In addition, the density of the empty minority spin states is decreased. This finding has been attributed to the presence of some Mn ions experiencing a different local chemical environment that results in the breaking of some DE paths, and in addition to an Anderson localisation of the charge carriers. This last conclusion can explain both the strongly insulating nature and the spin glass like behaviour of the magnetic response of the 50Å film, and has been corroborated by the results of the EXAFS analysis. [Copyright &y& Elsevier]

In this paper, we report the results about the synthesis and characterization of optimally doped La0.85Na0.15MnO3 thin films deposited onto SrTiO3 (100), NdGaO3 (100) and NdGaO3 (110) for thickness ranging from 11 to 82 nm. The effect of the substrate nature and orientation and film thickness was investigated in order to optimize the physical properties of the films. We obtained very smooth films displaying magnetoresistance values greater than 70% for temperature near to room temperature which makes them appealing for applicative purposes. [Copyright &y& Elsevier]