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., ...Daha Fazla

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS, cilt.31, sa.18, ss.15558-15564, 2020 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 31 Konu: 18
  • Basım Tarihi: 2020
  • Doi Numarası: 10.1007/s10854-020-04119-7
  • Dergi Adı: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
  • Sayfa Sayıları: ss.15558-15564

Özet

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.