Enhancement of Thermoelectric Properties in SnTe with (Ag, In) Co-Doping

• Published in: Journal of electronic materials 2018, Vol.47 (1), p.205-211
• Main Authors: Li, J. Q., Yang, N., Li, S. M., Li, Y., Liu, F. S., Ao, W. Q.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Doping; Electrical resistivity; Electronics and Microelectronics; Heat conductivity; Heat transfer; Instrumentation; Lead free; Materials research; Materials Science; Optical and Electronic Materials; Plasma sintering; Power factor; Precipitates; Quenching; Silver; Silver base alloys; Solid solutions; Solid State Physics; Spark plasma sintering; Thermal conductivity; Thermoelectricity; Tin
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-017-5745-9

A lead-free SnTe compound shows good electrical property but high thermal conductivity, resulting in a low figure-of-merit ZT . We present a significant enhancement of the thermoelectric properties of p -type SnTe with (Ag, In) co-doping. The Ag and In co-doped Sn 1−2 x Ag x In x Te ( x  = 0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) are prepared by melting, quenching and spark plasma sintering. A homogeneous NaCl-type SnTe-based solid solution forms in the alloys at low Ag and In content ( x  ≤ 0.02), while a AgInTe 2 minor secondary phase precipitates for higher x . Similar to In doping, the introduction of Ag and In at Sn sites in SnTe considerably increases the Seebeck coefficient and power factor by creating resonant levels near the Fermi energy. In addition, the Ag and In solute atoms in the SnTe-based solid solution and the minor secondary phase AgInTe 2 enhance phonon scattering and thus significantly reduce the carrier and lattice thermal conductivity. Ag and In co-doping shows a collective advantage on the overall thermoelectric performance of SnTe or In-doped SnTe. A maximum ZT of 1.23 at 873 K and average ZT of 0.58 can be obtained in the alloy Sn 1−2 x Ag x In x Te with x  = 0.03.