An apparatus for direct proton conductivity measurement of powdered materials

An apparatus with multiple sample cells for direct two-electrode electrochemical measurement of powdered materials (e. g., nanoparticles) has been designed and fabricated. Polyetherimide (PEI, ULTEM 1000) is chosen as the cell material because it is optically transparent, electrically insulating, and mechanically and chemically stable up to 170 degrees C. The sample cells are slim with high length-to-electrode-area ratio so that efficient, reliable, and nondestructive measurements of proton conductivity can be obtained on 20-30 mg powder samples using impedance spectroscopy at less than 2 x 10(5) Hz while still being able to eliminate the effects of contact resistance. Several electrode materials have been evaluated and data show 80% Pt-20% Ir electrodes adequately acid-resistant to avoid metal ion poisoning of the ion conductor. (c) 2005 The Electrochemical Society.