The N-doped TiO2 has been synthesized by\ud sol–gel method, using titanium isopropoxide, isopropanol\ud and an aqueous solution of ammonia with ratio 2:1:10. The\ud concentrations used for the NH3 aqueous solution were 3,\ud 7, 10 and 15 %. The samples have been analysed by X-ray\ud diffraction, electron microscopy (SEM and TEM) thermogravimetric\ud analysis (TGA), differential scanning calorimetry\ud (DSC), micro-Raman spectroscopy and diffuse\ud reflectivity. TEM, SEM, DSC and TGA showed that the\ud morphology is influenced by the presence of N3- ions but\ud not by the concentration of the solution. Instead reflectance\ud gave us a relation between values of the energy gap and the\ud concentration of N3- ions: the gap between valence and\ud conduction band lowers as the concentration of NH3 in the\ud starting solution increases. From these results we can say\ud that the properties of the material have been tuned by\ud doping with nitrogen ions because the particles absorb\ud more light in the visible range, and this is important for\ud photovoltaic and photocatalytic applications

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In order to contribute to the improvement of restoration and conservation sciences of metallic artefacts belonging to Cultural Heritage, a wide research has been started on the study of artificial (artistic) and natural (corrosion or alteration) patinas of copper-based alloys. Micro-Raman spectroscopy (mRS) coupled with scanning electron microscopy (SEM) equipped with energy Dispersive X-Ray Spectroscopy (EDXS) were applied for the characterization of a number of patinas made on metallic substrate reproducing the typical copper-based alloys used for statuary. A non alloyed copper sheet has been also used to simulate the architectural cover typically used after a specific cold spray coating. To reach these goals, a number of patinas were experimentally produced in our laboratory using the torch technique and reactive solutions based on water as a solvent containing, respectively, copper nitrate, iron nitrate and potassium sulfide (‘liver of sulfur’). The only exception is a sample reproducing the architectural cover of a recent building nearly completely covered with copper sheets coated with copper salts. All the produced patinas were aged in a salt spray chamber and then studied with mRS, SEM and EDXS in order to understand their evolution between the two known terms and therefore the reactions involved in all patinas. mRS allowedus todetect asmain constituents of the ‘artistic’ patinas, before and after ageing: copper oxides (Cuprite and Tenorite), copper nitrates (Rouaite and Gerhardtite), copper chlorides (Botallackite, Atacamite and Paratacamite), a copper sulfate (Posnjakite), iron oxides (Magnetite and Hematite) and an iron hydroxide (Limonite)

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