Substitution and proton doping effect on SrZrO sub(3) behaviour: high-pressure Raman study

The high-pressure Raman studies of pure, Yb-modified, protonated and non-protonated SrZrO sub(3) dense ceramics were performed between 0.1 and 40 GPa using a diamond anvil cell. Lanthanide-modified, protonated SrZrO sub(3) perovskites are potential materials for electrolytic membrane in fuel cells and electrolysers working at medium temperature. The comparison of the Raman spectra shows important differences in the pressure behaviour between the pure and Yb-modified SrZrO sub(3) ceramics. SrZrO sub(3) exhibits a rigid structure without any structural modification, whereas for both SrZr sub(0.93) Yb sub(0.07) O sub(2.965) and SrZr sub(0.93) Yb sub(0.07) O sub(2.962) H sub(0.003) a sequence of structural modifications at 10, 20 and 35 GPa is revealed. The character of these structural modifications is very similar to that observed as a function of the temperature (orthorhombic Pnma 750 degree C arrow right pseudo-tetragonal Imma 840 degree C arrow right tetragonal I4/mcm 1070 degree C arrow right cubic Pm3m), which suggests that they can be considered as the phase transitions. Despite the low level of proton content (0.3% mole/mole), significant difference between protonated and non-protonated compounds is observed for the 700-750 cm super(-1) doublet assigned to the Zr--O octahedron stretching mode, perturbed by an oxygen atom vacancy and/or neighbouring Yb ion. The location of proton is discussed. Copyright copyright 2011 John Wiley & Sons, Ltd. The pressure dependences of the low wavenumber mode widths reveal a rigid structure without any structural modification in the case of pure SrZrO sub(3) and the sequence of pressure-induced structural modifications for both Yb-modified non-protonated and protonated SrZrO sub(3). Perturbations of the host perovskite structure due to the Yb substitution and insertion of protonic species are discussed.