Approaching the Minimum Thermal Conductivity in Rhenium-Substituted Higher Manganese Silicides

Journal Article · Wed Jan 01 00:00:00 EST 2014 · Advanced Energy Materials

DOI:https://doi.org/10.1002/aenm.201400452· OSTI ID:1132985

Chen, Xi ^[1]; Girard, S. N. ^[2]; Meng, F. ^[2]; Lara-Curzio, Edgar ^[3]; Jin, S ^[2]; Goodenough, J. B. ^[1]; Zhou, J. S. ^[1]; Shi, L ^[1]

---

1. University of Texas at Austin
2. University of Wisconsin, Madison
3. ORNL

Higher manganese silicides (HMS) made of earth-abundant and non-toxic elements are regarded as promising p-type thermoelectric materials because their complex crystal structure results in low lattice thermal conductivity. It is shown here that the already low thermal conductivity of HMS can be reduced further to approach the minimum thermal conductivity via partial substitu- tion of Mn with heavier rhenium (Re) to increase point defect scattering. The solubility limit of Re in the obtained RexMn1 xSi1.8 is determined to be about x = 0.18. Elemental inhomogeneity and the formation of ReSi1.75 inclusions with 50 200 nm size are found within the HMS matrix. It is found that the power factor does not change markedly at low Re content of x 0.04 before it drops considerably at higher Re contents. Compared to pure HMS, the reduced lattice thermal conductivity in RexMn1 xSi1.8 results in a 25% increase of the peak figure of merit ZT to reach 0.57 0.08 at 800 K for x = 0.04. The suppressed thermal conductivity in the pure RexMn1 xSi1.8 can enable further investigations of the ZT limit of this system by exploring different impurity doping strategies to optimize the carrier concentration and power factor.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Revolutionary Materials for Solid State Energy Conversion (RMSSEC); Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1132985
• Journal Information: Advanced Energy Materials, Journal Name: Advanced Energy Materials Journal Issue: 14 Vol. 4; ISSN 1614-6832
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

thermal conductivity
thermoelectric