Acetylene adsorption on the iron-lead-borate glassy and vitroceramic surface

Abstract A novel iron-lead-borate glassy and vitroceramic system for applications in solar cells technology and adsorption of small molecules (such as acetylene) on surfaces was obtained and studied in this work. In this sense, glasses and glass ceramics of the xFe 2 O 3 ·(100 − x)[3B 2 O 3 ·PbO 2 ] system with x = 5–50 mol% Fe 2 O 3 were synthesized by melt quenching method and characterized in order to obtain information about their structural and behavioral properties. The reciprocal effects of the iron ions addition to the host matrix together with the matrix effect on the paramagnetic behavior of the inserted iron ions were investigated by using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV–Vis) spectroscopy and electron paramagnetic resonance (EPR) spectroscopy. The XRD pattern for the prepared samples shows their vitreous nature only for x ≤ 30 mol% Fe 2 O 3 . For samples containing 40 mol% Fe 2 O 3 , the presence of α-Fe 2 O 3 crystalline phase embedded in an amorphous matrix was detected. IR data suggest that addition of high iron (III) oxide content in the host matrix leads to the gradual conversion of [PbO 4 ] to [PbO 3 ] and [BO 4 ] to [BO 3 ] structural units and the formation of [FeO n ] structural units by modifications of Pb O B and Pb O Pb linkages. The UV–Vis data show that addition of higher Fe 2 O 3 concentration produces a gradual shift of the absorption towards the higher wavelength side indicating the absorption of light from 295 to 1050 nm and a decrease of the energy gap. EPR spectra exhibit resonance signals at g ~ 4.3 and g ~ 2 showing the presence of Fe + 3 ions in sites of distorted octahedral symmetry as well as in clusters containing both Fe + 3 and Fe + 2 ionic species. FTIR spectroscopy was employed to study the adsorption of acetylene on the obtained glasses and vitroceramics surface. The nature of the different molecular species is also discussed.