Drastic modification of low temperature thermoelectric properties of Na-doped Bi(2)Sr(2)Co(2)O(y)ceramics prepared via laser floating zone technique

Cetin G., Ozcelik B., Gursul M., Madre M. A., Sotelo A., Adachi S., ...More

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS, vol.31, no.18, pp.15558-15564, 2020 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 31 Issue: 18
  • Publication Date: 2020
  • Doi Number: 10.1007/s10854-020-04119-7
  • Journal Name: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Applied Science & Technology Source, Chemical Abstracts Core, Communication Abstracts, Compendex, Computer & Applied Sciences, INSPEC, Metadex, Civil Engineering Abstracts
  • Page Numbers: pp.15558-15564
  • Çukurova University Affiliated: Yes

Abstract

In this study, Bi2Sr2-xNaxCo2Oy(x = 0.0, 0.05, 0.075, 0.10, and 0.15) ceramic powders have been fabricated via the classical ceramic route, followed by a texturing process through the laser floating zone technique. XRD patterns show the thermoelectric phase as the major one. In addition, Na-substitution reduces the amount of secondary phases, when compared to the pure sample. SEM observations point out that grain orientation is significantly improved when Na-content is increased. Na-substitution reduces electrical resistivity from 35 (in pure samples) to 19.6 m omega cm (in Na = 0.05 ones) at around room temperature, while Seebeck coefficient is, approximately, twice measured in Na-free. On the other hand, thermal conductivity is slightly lower in undoped samples (0.83 W/K m), when compared to the Na-substituted ones (1.10-1.40 W/K m) at room temperature, due to their lower electrical conductivity. Finally, ZT values are higher when the Na-content is increased, reaching 0.022 at around 400 K.