0000000000879247
AUTHOR
F Di Quarto
Recent advances in using Photocurrent Spectroscopy for the Characterization of Passive Films on Metals and Metallic Alloys
La Spettroscopia a Fotocorrente (PCS) viene qui presentata come tecnica d’indagine non distruttiva, utile per lo studio delle proprietà elettroniche di film passivi accresciuti su metalli e leghe metalliche. In questo lavoro sono stati studiati tramite PCS film passivi di acciai inossidabili quali AISI 304L, AISI 316L e Duplex 2507, accresciuti in soluzione 0.25 M di NaOH a 82°C, condizione simulante l’ambiente aggressivo tipico di operazioni di pulizia nell’industria del food and beverage. Il band gap dei film passivi cambia notevolmente dopo l’immersione per gli acciai 304L e 316L, con un arricchimento in Fe dei film passivi durante il trattamento. Per l’acciaio Duplex invece, il film pas…
Band Gap Modeling of Different Ternary and Quaternary Alumina Garnet Phases Y3(AlXGa1-X)5O12 (YAGG) and Lu3(AlXGa1-X)5O12 (LuAGG). A Semiempirical Approach
A further generalization to quaternary oxide systems of the modeling equation of optical band gap values, based on the semiempirical correlation between the differences in the electronegativity of oxygen and the average cationic electronegativity, proposed some years ago, has been carried out by expanding the approach recently employed for ternary mixed oxides. The choice of oxide polymorphs and their influence on the fitting procedure of an experimental data set is evidenced by a detailed discussion of the fitting process of the literature's experimental band gap data pertaining two quaternary oxide systems of the garnet family, namely, Y3(AlxGa1-x)5O12 (YAGG) and Lu3(AlxGa1-x)5O12 (LuAGG)…
Photoelectrochemical Synthesis of Polypyrrole on Anodic Ta2O5 Films
Polypyrrole film was photoelectrochemically grown on insulating Ta2O5 anodic film in acetonitrile solution. A characterization by photocurrent spectroscopy PCS of metal/oxide/polypyrrole interface was carried out. The PCS results suggest that a metallic-like PPy is formed under illumination at constant anodic potential. By polarizing the polypyrrole at cathodic potentials a photocurrent spectrum typical of p-type semiconducting film was recorded. A scanning electron microscopy study of PPy surfaces solution side and oxide side allowed us to obtain information on the morphology of the polymer as well as a rough estimate of the film thickness and of the diameter of PPy globules at the two int…