Ion transport in some solid state proton conducting composites studied from volta cell e.m.f. and complex impedance spectroscopy

[摘要] Proton conducting composites of heteropolyacid hydrates (phosphomolybdic acid H₃PMo₁₂O₄₀.ð‘�?�H₂O,PMA; phosphotungstic acid H₃PW₁₂O₄₀.ð‘�?�H₂O, PTA) and salt hydrate like NiCl₂.6H₂O were prepared with insulating Al₂O₃ as dispersoid. The ionic conductivity peaks at two concentrations of Al₂O₃ indicating two percolation thresholds for proton conduction. Two separate experiments were carried out to check the existence of such percolation thresholds viz. the volta battery experiment involving the measurement of e.m.f. of an electrochemical cell with composites of different compositions used as electrolyte and the composition vs conductivity measured by the complex impedance spectroscopy. The presence of two maxima has been attributed to two different percolation thresholds for the two possible mobile protonic species 𝐻⁺ (H₃O⁺) and OH^â€�?? arising from the hydrates.

[学科分类] 材料工程

[关键词] Interface;ionic transport;composites.