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Interstitial Copper Doping and Thermally Activated Rattling in La3- xTe4 for Enhanced Thermoelectric Performance.
Feng Qiao1, Fei Jia2, Yan Cao1
1State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan, China.
Angewandte Chemie (International Ed. in English)
|June 24, 2026
Summary
Copper doping in lanthanum telluride (La₂Te₄) enhances thermoelectric performance for radioisotope thermoelectric generators. This interstitial doping strategy improves efficiency by optimizing electronic properties and reducing heat transfer.
Area of Science:
- Materials Science
- Solid State Physics
- Thermoelectrics
Background:
- Lanthanum telluride (La₂Te₄) materials show promise for radioisotope thermoelectric generators (RTGs) due to high-temperature stability and good thermoelectric properties.
- Traditional doping methods for La₂Te₄ struggle to simultaneously optimize electronic properties and reduce thermal conductivity.
- Interstitial doping offers a novel approach to decouple and optimize these competing factors.
Purpose of the Study:
- To investigate the effect of copper (Cu) interstitial doping on the thermoelectric properties of La₂Te₄.
- To explore simultaneous optimization of electrical transport and thermal conductivity through interstitial doping.
- To enhance the thermoelectric figure of merit (zT) for improved RTG applications.
Main Methods:
- Synthesis of a series of Cu-doped La₂.₇₄CuₓTe₄ (x = 0, 0.01, 0.05, 0.1, 0.15) samples.
- Characterization of thermoelectric properties, including Seebeck coefficient, power factor, and thermal conductivity.
- Analysis of lattice thermal conductivity reduction mechanisms, focusing on phonon scattering and anharmonicity.
Main Results:
- Cu incorporation enhanced the Seebeck coefficient while maintaining a competitive power factor.
- Lattice thermal conductivity was significantly suppressed due to Cu doping-induced anharmonic vibrations and enhanced phonon scattering.
- La₂.₇₄Cu₀.₀₅Te₄ achieved a peak thermoelectric figure of merit (zT) of 1.58 at 1073 K, a 34% improvement over the undoped sample.
- An average zT of 1.5 was achieved between 873-1073 K, representing a 71.3% increase compared to previous state-of-the-art lanthanum telluride materials.
Conclusions:
- Interstitial Cu doping is an effective strategy for simultaneously enhancing the electronic and thermal transport properties of La₂Te₄.
- The optimized La₂.₇₄Cu₀.₀₅Te₄ composition demonstrates superior thermoelectric performance, making it a highly competitive material for next-generation RTGs.
- This work highlights the potential of interstitial doping in thermoelectric materials for advanced energy conversion applications.
