Thermoelectric Performance Optimization of n-Type La3−xSmxTe4/Ni Composites via Sm Doping

• Published in: Energies (Basel) Vol. 15; no. 7; p. 2353
• Main Authors: Li, Jian, Song, Qingfeng, Liu, Ruiheng, Dong, Hongliang, Zhang, Qihao, Shi, Xun, Bai, Shengqiang, Chen, Lidong
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.04.2022
• Subjects: carrier concentration optimization; Carrier density; composite; Composite materials; Crystal structure; Doping; Efficiency; Heat conductivity; Heat transfer; High temperature; Hot pressing; lanthanum telluride; Optimization; Point defects; Rare earth elements; Samarium; Scanning electron microscopy; Substitutes; Tellurides; Thermal conductivity; Thermal stability; thermoelectric; Thermoelectric generators; Thermoelectric materials; Thermoelectricity; Transport properties; Germany
• ISSN: 1996-1073; 1996-1073
• DOI: 10.3390/en15072353

La3Te4-based rare-earth telluride is a kind of n-type high-temperature thermoelectric (TE) material with an operational temperature of up to 1273 K, which is a promising candidate for thermoelectric generators. In this work, the Sm substitution in La3−xSmxTe4/Ni composites is reported. The electrical transport property of La3−xSmxTe4 is modified by reducing carrier concentration due to the substitution of Sm2+ for La3+. The electric thermal conductivity decreases by 90% due to carrier concentration reduction, which mainly contributes to a reduction in total thermal conductivity. Lattice thermal conductivity also decreases by point-defect scattering by Sm doping. Meanwhile, based on our previous study, compositing nickel improves the thermal stability of the La3 − xSmxTe4 matrix. Finally, combined with carrier concentration optimization and the decreased thermal conductivity, a maximum zT of 1.1 at 1273 K and an average zTave value of 0.8 over 600 K–1273 K were achieved in La2.315Sm0.685Te4/10 vol.% Ni composite, which is among the highest TE performance reported in La3Te4 compounds.