Structural and thermal characterization of phosphate based glasses promising for hydrogen absorption

Among the applications of phosphate glasses, one of the most promising is their potential as catalysts for water dissociation into hydrogen and oxygen and to absorb hydrogen in its structure, making them good candidates to be used as electrolytes in intermediate temperature fuel cells (200-500 °C). Phosphate based glasses with molar composition 30PO5/2-25NbO5/2-10WO3-25Na2O-10[(1-x)BaO-xSrO], with x = 0, 20, 50, 60, 80 and 100 mol% were prepared by the melt quenching technique. The as-prepared samples revealed to be transparent, mechanical and thermally stable at room temperature. Differential thermal analysis (DTA) measurements showed Tg values around 500 °C, and high thermal stability. The structure of the samples was studied by X-Ray powder Diffraction (XRD) Raman spectroscopy, and the morphology by Scanning Electron Microscopy (SEM). Dc (σdc) and ac (σac) conductivities and dielectric spectroscopy measurements were performed as function of temperature (100-370 K) presenting a conductivity predominantly ionic (σelectronic/σionic of about 10− 4). The dielectric spectroscopy was measured in the frequency range 100 Hz-1 MHz.