Glassy Thermal Transport Triggers Ultra‐High Thermoelectric Performance in GeTe
Abstract
Abstract The consequences of broken long‐range atomic arrangement in glasses or amorphous solids are reflected in the temperature dependence of lattice thermal conductivity (κ lat ). However, the appearance of glassy ultralow κ lat in a crystalline solid with high electrical transport like metal is unusual but can have a remarkable impact on the thermoelectric performance of a material. Here, an ultra‐high thermoelectric performance is demonstrated with a maximum figure of merit, zT ≈ 2.7 (≈2.92 with Dulong–Petit heat capacity) via achieving glassy thermal transport along with significant electrical conductivity in ball milled BiSe, Pb co‐doped polycrystalline Ge 1.03 Te followed by spark plasma sintering. The glassy thermal transport results from the inhomogeneous ferroelectric instability developed due to local polar distortions near the dopant sites, which interacts with soft polar optical modes via strain fluctuations. Resulting structural degeneracy and associated soft vibrations sink heat effectively from acoustic phonons, which along with various nanoscale defects, confine the phonon mean free path (MFP) close to the interatomic distance, rendering the thermal transport glassy. However, the material still maintains a high electrical conductivity at ambient condition due to much longer MFP of the charge carriers. A promising output power density of ≈0.8 W cm −2 for ΔT ≈441 K in double‐leg thermoelectric device demonstrate the potential of this material for mid‐temperature thermoelectric applications.
Article Details
Authors (15)
Debattam Sarkar
Department of Chemistry
Subarna Das
New Chemistry Unit, and School of Advanced Materials and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore 560064, India
Vaishali Taneja
New Chemistry Unit, and School of Advanced Materials and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore 560064, India
Manisha Samanta
New Chemistry Unit, International Centre for Materials Science and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore 560064, India
Koushik Jagadish
Animesh Das
New Chemistry Unit, International Centre for Materials Science and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore 560064, India
Monika Bhakar
Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli 140306, India
Prasad V. D. Matukumilli
Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, Jakkur P.O. 560064, India
Suresh Perumal
Department of Materials Science and Metallurgical Engineering Indian Institute of Technology Hyderabad Telangana 502285 India
Goutam Sheet
Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli 140306, India
Dirtha Sanyal
Variable Energy Cyclotron Centre 1/AF Bidhannagar Kolkata 700064 India
Koushik Pal
Department of Physics
N. Ravishankar
Materials Research Centre
Umesh V. Waghmare
Theoretical Sciences Unit, and School of Advanced Materials and International Centre for Materials Science
Kanishka Biswas
New Chemistry Unit, and School of Advanced Materials and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore 560064, India