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Boosting the Thermoelectric Performance of Calcium Cobaltite Composites through Structural Defect Engineering
Zongmo Shi1,2, Can Zhang1, Taichao Su3
1State Key Laboratory of Solidification Processing, MIIT Key Laboratory of Radiation Detection Materials and Devices, USI Institute of Intelligence Materials and Structure, School of Material Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, P. R. China.
This study enhances thermoelectric performance in misfit-layered calcium cobalt oxide (Ca3Co4O9) using La3+ doping and silver nanoparticles. Optimized composites show improved ZT values, paving the way for better thermoelectric devices.
Area of Science:
- Materials Science
- Solid State Chemistry
- Nanotechnology
Background:
- Misfit-layered Ca3Co4O9 is a promising p-type semiconductor for thermoelectric applications.
- Its commercialization is hindered by relatively poor thermoelectric performance.
Purpose of the Study:
- To improve the thermoelectric performance of Ca3Co4O9.
- To investigate the effects of La3+ doping and nano-sized Ag addition on Ca3Co4O9.
- To understand the role of multiscale microstructural defects in enhancing thermoelectric properties.
Main Methods:
- Spark plasma sintering was used to prepare Ca2.7-xLaxAg0.3Co4O9/Ag composites.
- Systematic variation of La3+ dopant levels and nano-sized Ag content.
- Microstructural analysis to identify stacking faults, dislocations, and oxygen vacancies.
- Evaluation of charge carrier and phonon transport properties.
Main Results:
- Multiscale microstructural defects (stacking faults, dislocations, oxygen vacancies) were introduced.
- Nano-sized Ag particles at grain boundaries increased charge carrier concentration.
- Structural defects acted as phonon scattering centers, reducing thermal conductivity.
- The Ca2.61La0.09Ag0.3Co4O9/Ag sample achieved a peak ZT of 0.35 at 1073 K.
Conclusions:
- The interplay of structural defects significantly enhances thermoelectric performance.
- La3+ doping and Ag addition are effective strategies to tune thermoelectric properties in Ca3Co4O9.
- This research offers a pathway for developing high-performance thermoelectric materials.
