Structural study and proton conductivity of BaZr0.90Ga0.10O2.95
Artikel i vetenskaplig tidskrift, 2006
Traditional solid state sintering has been used to prepare the perovskite BaZr0.9Ga0.1O2.95. Analysis of X-ray powder diffraction data shows that a decrease of the unit cell parameter a was observed compared to the undoped BaZrO3, which confirms successful substitution of Ga3+ for Zr4+ at the B site. Rietveld analysis of room temperature neutron powder diffraction data confirmed cubic symmetry (space group Pm-3m) for both as- prepared and deuterated BaZr0.90Ga0.10O2.95 samples. The strong O-H stretch band (2500-3500 cm−1) in the infrared absorbance spectrum clearly manifests the presence of protons in the pre-hydrated material. The bulk and total conductivities of prehydrated BaZr0.9Ga0.1O2.95 are 1.17 × 10−5 and 3.55 × 10−6 Scm−1, respectively at 400°C, which are more than one order of magnitude higher than for dried a sample at the same temperature. In contrast, the total conductivity of pre-hydrated and dried samples is similar at higher temperature, e. g. T > 800 °C. The higher activation energy (e. g. 0.7 eV) for pre-hydrated sample compared to typical value (0.4-0.5 eV) of proton conduction may suggest that the protons are trapped in the material.