This paper reports the growth of bismuth tri-iodide thick films intended for direct and digital X-ray imaging. Films were grown by the vertical physical vapor deposition method, onto glass substrates 2"x 2" in size, with gold previously deposited as rear electrode. The film thickness was up to 33 µm (±5 %). Optical microscopy and SEM were performed on the films and grain size resulted to be up to 40 µm. A strong correlation was found between the microcrystals growth orientation and the growth temperature. At low temperatures, microcrystals grow with their c axis parallel to the substrate, whereas at higher temperatures, they grow with their c axis perpendicular to the substrate. The higher the growth temperature, the lower the dark current of the film, and the higher the resistivity, which was from 10 13 to 10 15 Ωcm. A sensitivity to X-rays of 6.9 nC/R.cm 2 was measured irradiating the films with X-rays from a mamographer. Film properties were correlated with the growth temperature, with previous results for bismuth tri-iodide films and monocrystals and with data for films of alternative materials such as lead and mercuric iodide.

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Biocarbon monoliths were obtained from Eucalyptus grandis and the influence of wood anisotropy on the electrical and electrochemical performance as supercapacitor electrodes was studied. They were produced from wood pieces cut along the transversal and longitudinal direction of the tree trunk, followed by pyrolysis and, for some of them, also by activation with CO 2 . Monoliths with drilled channels were also obtained. All the monoliths were characterized by SEM, nitrogen adsorption/desorption isotherms, electrical conductivity measurements and electrochemical measurements, the latter in 2M aqueous H 2 SO 4 electrolyte. Electrical conductivity and specific capacitance are higher for the transversal carbon monoliths than for the longitudinal ones. The electrical conductivity reaches values up to 27 S cm −1 for the transversal monolith. The specific capacitance reaches values up to 260 F g −1 for the transversal monolith that was activated and drilled. However, the highest volumetric capacitance, of 90 F cm −3 , is found for the longitudinal monolith that was activated and non-drilled. The energy density and power density, both referred to gravimetric and volumetric magnitudes, reach values as high as 36 Wh kg −1 and 12 Wh L −1 , and 2181 W kg −1 and 783 W L −1 , respectively. Comparison with a commercial powder activated carbon is provided.

An electrical double-layer capacitor (EDLC) is based on the physical adsorption/desorption of electrolyte ions onto the surface of electrodes. Due to its high surface area and other properties, such as electrochemical stability and high electrical conductivity, carbon materials are the most widely used materials for EDLC electrodes. In this work, we study an activated carbon felt obtained from sheep wool felt (ACF'f) as a supercapacitor electrode. The ACF'f was characterized by elemental analysis, scanning electron microscopy (SEM), textural analysis, and X-ray photoelectron spectroscopy (XPS). The electrochemical behaviour of the ACF'f was tested in a two-electrode Swagelok ®-type, using acidic and basic aqueous electrolytes. At low current densities, the maximum specific capacitance determined from the charge-discharge curves were 163 F•g −1 and 152 F•g −1 , in acidic and basic electrolytes, respectively. The capacitance retention at higher current densities was better in acidic electrolyte while, for both electrolytes, the voltammogram of the sample presents a typical capacitive behaviour, being in accordance with the electrochemical results.