Melt-Spun SiGe Nano-Alloys: Microstructural Engineering Towards High Thermoelectric Efficiency

Avinash Vishwakarma, Nagendra S. Chauhan, Ruchi Bhardwaj, Kishor Kumar Johari, Sanjay R. Dhakate, Bhasker Gahtori, Sivaiah Bathula

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Abstract: Silicon-germanium (SiGe) alloys are prominent high-temperature thermoelectric (TE) materials used as a powering source for deep space applications. In this work, we employed rapid cooling rates for solidification by melt-spinning and rapid heating rates for bulk consolidation employing spark plasma sintering to synthesize high-performance p-type SiGe nano-alloys. The current methodology exhibited a TE figure-of-merit (ZT) ≈ 0.94 at 1123 K for a higher cooling rate of ∼3.0 × 107 K/s. This corresponds to ≈ 88% enhancement in ZT when compared with currently used radioisotope thermoelectric generators (RTGs) in space flight missions, ≈ 45% higher than pressure-sintered p-type alloys, which results in a higher output power density, and TE conversion efficiency (η) ≈ 8% of synthesized SiGe nano-alloys estimated using a cumulative temperature dependence (CTD) model. The ZT enhancement is driven by selective scattering of phonons rather than of charge carriers by the high density of grain boundaries with random orientations and induced lattice-scale defects, resulting in a substantial reduction of lattice thermal conductivity and high power factor. The TE characteristics of synthesized alloys presented using the constant property model (CPM) and CTD model display their high TE performance in high-temperature regimes along with wide suitability of segmentation with different mid-temperature TE materials. Graphic Abstract: [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)364-374
Number of pages11
JournalJournal of Electronic Materials
Issue number1
Publication statusPublished - 2021 Jan
Externally publishedYes


  • SiGe alloys
  • lattice thermal conductivity
  • melt-spun
  • rapid solidification
  • spark plasma sintering

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering


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