Scheelite type Sr_1-xBa_xWO₄ (x = 0.1, 0.2, 0.3) for possible application in Solid Oxide Fuel Cell electrolytes

Area of Science:

• Materials Science
• Solid State Chemistry
• Electrochemistry

Background:

• Solid oxide fuel cells (SOFCs) require stable electrolytes with high ionic conductivity.
• Developing novel materials for intermediate-temperature SOFCs (IT-SOFCs) is crucial for broader application.
• Scheelite-type structures offer potential for ionic conductivity.

Purpose of the Study:

• To synthesize and characterize polycrystalline Sr_1-xBa_xWO₄ (SBW) materials.
• To evaluate their phase stability and ionic conductivity for SOFC applications.
• To investigate proton uptake and conductivity under relevant conditions.

Main Methods:

• Solid-state sintering method for material synthesis.
• X-ray diffraction (XRD) and Rietveld analysis for structural characterization.
• Scanning Electron Microscopy (SEM) for microstructure analysis.
• Thermogravimetric Differential Scanning Calorimetry (TG-DSC) for thermal analysis and proton uptake.
• Ionic conductivity measurements under wet argon atmosphere.

Main Results:

• All synthesized SBW compounds (x=0.1, 0.2, 0.3) crystallized in a single-phase tetragonal scheelite structure (I4₁/a).
• SEM confirmed the formation of highly dense microstructures.
• TG-DSC indicated significant proton uptake at elevated temperatures.
• SBW (x=0.3) exhibited the highest ionic conductivity (1.9 × 10^-6 S cm^-1 at 1000°C) among the studied compounds under wet conditions, though lower than traditional BCZY perovskites.

Conclusions:

• The synthesized scheelite-type SBW materials possess structural stability and demonstrate proton conductivity.
• SBW (x=0.3) shows the most promising ionic conductivity within this series.
• This new series of SBW materials could potentially be utilized as proton conducting electrolytes in IT-SOFCs.