Preparation of stabilized Gd-doped BaPrO₃ materials by Zr substitution

The synthesis of a Gd-doped BaPrO3–BaZrO3 solid solution has been investigated in an effort to stabilize the BaPrO3 perovskite, a system with poor chemical stability and endurance for humid, CO2 and reducing conditions. The phases BaZrxPr1−xGd0.3O3−δ (x = 0–0.7, Δx = 0.1) have been prepared by acrylamide combustion synthesis. The solid solution is characterized by X-ray powder diffraction, scanning electron microscope (SEM) and durability against CO2, moisture and reducing conditions investigated. Crystal structure parameters were obtained from X-ray powder diffraction data and results show its symmetry increases by increasing Zr content. BaZr0.1Pr0.6Gd0.3O3−δ has a maximum weight increase due to reaction with CO2 of nearly 13%, while this is reduced below 2% for BaZr0.5Pr0.2Gd0.3O3−δ. The material appears to be unaltered by 5%H2/Ar for x ≥ 0.5, and under wet Ar for x ≥ 0.4, and thus render a higher chemical stability and confirms the stabilizing role of BaZrO3. However, microstructure investigations reveal gadolinium segregation due to the high doping level of the perovskite.