Water vapor solubility and impedance of the high temperature proton conductor SrZr0.9Y0.1O2.95

SrZr0.9Y0.1O2.95 was prepared at rather high sintering temperatures. Thermogravimetry resulted in a maximum proton solubility of about 0.04 mol/mol compound. The standard enthalpy and entropy of the solution process were determined. Impedance results are presented for various gas atmospheres ranging from oxidizing to very reducing, and from dry to very moist. Clear evidence for proton conduction was obtained. The conductivity of the protonated samples was found to increase linearly with the proton content determined independently by weight measurements. From the data, the activation energy and the prefactor of the proton mobility were extracted and compared with literature values, In addition to water vapor. atmospheres proton uptake was observed by impedance spectroscopy (IS) in acetone vapors where argon was used as inert carrier gas. At temperatures above 450-500 degreesC, such a treatment led to the undesirable deposition of a carbonaceous layer on the surfaces. The mechanism of proton incorporation by acetone vapor presumably is ion exchange reactions where protons enter into the bulk and Sr segregates in the surface region. (C) 2001 Elsevier Science BN. All rights reserved.