Mechanical degradation under hydrogen of yttrium doped barium zirconate electrolyte material prepared with NiO additive

• Solid State Reactive Sintering (SSRS) produces BaZr0.85Y0.15O3-δ with NiO impurity.
• Mechanical properties of SSRS-made BaZr0.85Y0.15O3-δ are degraded under hydrogen.
• NiO impurity can be reduced to metallic Ni in hydrogen atmosphere.
• Ni-rich impurity induced by SSRS may lead to accelerated cell failure.

Recently, a novel process was presented to fabricate dense yttrium-doped barium zirconate electrolytes with high proton conductivity. This process was based on the use of a NiO additive during reactive sintering. We show here that materials made from this process present a fast degradation of mechanical properties when put in hydrogen-rich conditions, while material made from conventional sintering without NiO aid remains intact in the same conditions. The fast degradation of samples made from reactive sintering, leading to sample failure under highly compressive conditions, is due to the reduction of NiO nanoparticles at grain boundaries as shown from structural and chemical analyses using Transmission Electron Microscopy. By the present study, we alert about the potential risk of cell failure due to this mechanical degradation.

We observe a degradation of mechanical properties under hydrogen of BaZr0.85Y0.15O3−δ sample made with NiO sintering aid. The origin of this evolution is due to the reduction by hydrogen of NiO particles located at grain boundaries.Figure optionsDownload as PowerPoint slide