High-throughput measurement of ionic conductivity in composition-spread thin films

Area of Science:

• Materials Science
• Solid-State Chemistry
• Electrochemistry

Background:

• Ionic conductivity is crucial for oxygen-ion conductors used in various energy applications.
• Yttria-stabilized zirconia (YSZ) is a key material, but its thin-film conductivity requires precise measurement techniques.
• Investigating conductivity in thin films is challenging due to electrode effects and grain boundary contributions.

Purpose of the Study:

• To demonstrate a high-throughput method for investigating ionic conductivity in oxygen-ion conductors.
• To systematically measure the intragrain ionic conductivity of YSZ thin films as a function of yttria concentration.
• To validate the use of in-plane electrode configurations for accurate thin-film conductivity measurements.

Main Methods:

• Preparation of YSZ composition-spread thin films with nanometer-size grains using 90° off-axis reactive RF cosputtering.
• Comparison of out-of-plane (parallel plate) and in-plane (planar interdigitated) electrode configurations.
• Systematic measurement of intragrain oxygen ion conductivity across varying yttria concentrations (2-12 mol %).

Main Results:

• The in-plane electrode configuration effectively minimizes electrode effects, allowing for explicit measurement of intragrain conductivity in 150 nm YSZ thin films.
• Measured conductivity closely matches bulk material values, with a peak conductivity of approximately 3 × 10⁻⁴ S cm⁻¹ at 440 °C.
• The optimal yttria concentration for peak conductivity was found to be 8 mol % Y₂O₃.

Conclusions:

• The developed high-throughput technique is feasible for investigating ionic conductivity in oxygen-ion conductor thin films.
• This method enables accurate characterization of novel chemical systems where bulk measurements are not feasible.
• The findings contribute to the understanding and optimization of YSZ thin films for potential applications.