Enhancing Strategy of the Small-Polaron Conductivity in LaCrO₃: First-Principles Calculations and Experimental...

Area of Science:

• Materials Science
• Solid State Chemistry
• Condensed Matter Physics

Background:

• Lanthanum chromite (LaCrO₃) shows promise for transparent conductors, sensors, and power generators.
• Challenges include chromium volatility, low conductivity due to small polarons, and wide band gap.

Purpose of the Study:

• To enhance LaCrO₃ properties via band and defect engineering.
• To screen doping strategies for reduced Cr volatility and improved conductivity.
• To analyze the small-polaron conduction mechanism.

Main Methods:

• First-principles calculations to screen doping schemes.
• Solid-state synthesis of codoped LaCrO₃ with Ca and Zn.
• Characterization of electrical conductivity and Seebeck coefficient.

Main Results:

• Zn doping enhanced Cr-O bond strength, suppressing Cr volatility and improving stability.
• Zn introduced impurity levels, altering small polaron mobility and increasing conductivity.
• Optimized La_0.7Ca_0.3Cr_0.95Zn_0.05O₃ showed conductivity increase from 7 to 60 S/cm at 1000 K.
• Increased Seebeck coefficient observed, beneficial for sensors.

Conclusions:

• Codoping LaCrO₃ with Ca and Zn is an effective strategy for performance optimization.
• The approach significantly enhances electrical conductivity and high-temperature stability.
• Optimized material shows potential for advanced high-temperature sensor and power generation applications.