Low temperature thermoelectric properties of K-substituted Bi2Sr2Co2Oy ceramics prepared via laser floating zone technique

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ÖZÇELİK B., ÇETİN G., GÜRSUL M., MADRE M. A., SOTELO A., ADACHİ S., ...Daha Fazla

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, cilt.39, sa.10, ss.3082-3087, 2019 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 39 Sayı: 10
  • Basım Tarihi: 2019
  • Doi Numarası: 10.1016/j.jeurceramsoc.2019.04.029
  • Dergi Adı: JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.3082-3087
  • Anahtar Kelimeler: Thermoelectric oxides, Texture, Microstructure, Electrical properties, Figure of Merit, MAGNETIC-PROPERTIES, CRYSTAL-STRUCTURE, HIGH-PERFORMANCE, IMPROVEMENT, POWER, MICROSTRUCTURE, COBALTITES, FIGURE, PHASE
  • Çukurova Üniversitesi Adresli: Evet

Özet

In the present study, Bi2Sr2-xKxCo2Oy (x = 0.0, 0.050, 0.075, 0.100, and 0.15) ceramic precursors have been produced using the classical ceramic route, followed by texturing through the laser floating zone technique. XRD results show that the thermoelectric phase is the major one in all cases. Moreover, K-substitution decreases the secondary phases content, when compared to the undoped sample. SEM observations indicate that grain orientation is significantly enhanced when K-content is increased. K-doping decreases electrical resistivity from 32 10(-5) Omega m (in undoped samples) to 20-22 10(-5) Omega mat 300 K, while increasing Seebeck coefficient from 55 mu V/K to 100-117 mu V/K at 300 K. On the other hand, thermal conductivity is slightly lower in undoped samples (0.93 W/K m, compared to 1.10-1.28 W/K m for doped ones at 300 K), due to their lower electrical conductivity. Finally, ZT values are higher when the K-content increases up to x = 0.10, reaching 0.029 at around 400 K, and slightly decreasing for higher doping levels.