A structurally modified 85SiO2–9P2O5–6TiO2 system and its dynamic dielectric behavior–a starting point for hydrogen detection

Abstract

Novel proton conducting materials with composition 85SiO2–9P2O5–6TiO2, modified by addition of liquid xH3PO4 in different amounts xH3PO4 = 0; 17; 35; 52 mmol, were synthesized via sol–gel route. XRD patterns show amorphous nature for “pure” (xH3PO4 = 0 mmol) sample and crystalline for all H3PO4-doped samples. FTIR and SEM analysis revealed that this modification led to appreciable structural changes on molecular level and morphology, which, heavily impacts the water intake ability, impedance behavior as well as the dielectric parameters. The detailed impedance examination showed distinct response of changing parameters such as relative humidity and temperature, while the dielectric parameters derived from the impedance spectra, provide in-depth understanding of proton conduction dynamic. Based on these observations different models were proposed gathering proton transfer in humid and dry atmospheres. The enhanced proton conduction is a basic requirement for successful usage of the material for hydrogen gas detection.

Keywords

• Phosphoric acid-doped SiO2–P2O5–TiO2 system
• Sol–gel
• Impedance spectroscopy
• Dielectric relaxation
• Hydrogen detection
• Infrared structural study