Infrared Absorption Spectra of High Temperature Proton Conducting Ca2 + -Doped La2Zr2 O 7

Abstract

Infrared (IR) absorption spectra of pyrochlore-type -doped proton conductors, i.e., and systems, were studied by the diffuse reflection method. The O-H stretching vibrations due to the protons dissolved in the crystal with negligible effects of adhesion and/or adsorption water could be detected by improvement of the sample preparation and the diffuse reflection technique. The bands, due to protons dissolved in the crystal, were distinctly different between the and the systems; three bands at 3517, 3401, and 3323 cm−1 for the system and six bands at 3517, 3430, 3414, 3371, 3341, and 3289 cm−1 for the system were observed. The stable sites for dissolved protons were distinctly different between the two systems. The wave numbers and the widths of the bands were higher and much sharper than those reported for the well-known perovskite-related-type proton conductors. It was concluded that the O-H bonds in -doped crystal are tight compared with perovskite-related-type proton conductors, and that definite stable sites for protons exist in -doped crystal. In the IR spectra of samples with various water vapor pressures, of proton dissolution treatment, the preferred dissolution of protons into the specific site was observed under low atmosphere. The details of the dissolution environment of protons are also discussed. © 2001 The Electrochemical Society. All rights reserved.