High-resolution electron microscopy of thermoelectric compounds Bi-(Sr,Ba)-Rh-O

Kunio Yubuta, S. Okada, Yuzuru Miyazaki, I. Terasaki, T. Kajitani

研究成果: Conference contribution


The crystal structures of thermoelectric (TE) compounds Bi 1.91 Sr 2.0 Rh 1.77 O x and Bi 2.12 Ba 2.00 Rh 1.95 O x are investigated by means of electron diffraction measurements and high-resolution electron microscopy. These compounds have layered structures and consist of two interpenetrating subsystems exhibiting incommensurated periodicities along b-axis. Both subsystems, CdI 2 -type RhO 2 sheets and a distorted four-layered rock-salt (RS)-type (Bi,(Sr,Ba))O blocks, have common a-, c-axes and β-angles. On the other hand, the ratios of two axis lengths, i.e., b 1 (RhO 2 sheet) / b 2 (RS-type block), are irrational. Based on the cation ratio and b 1 /b 2 value, the structural formulae are expressed as [(Bi 1-x Rh x ) 2 (Sr 1-y Bi y ) 2 O 4+δ ] 0.63 RhO 2 with x=0.077, y=0.016 and δ=0.46 for the Sr-system and [(Bi 1-x Rh x ) 2 (Ba 1-y Bi y ) 2 O 4+δ ] 0.56 RhO 2 with x=0.037, y,=0.047 and δ=0.39 for the Ba-system, respectively. Based on the electron diffraction measurements, it is found that these compounds have irrational modulation vectors, q1 = - a* + 0.63b1* and q2 = 0.17b1* + c for Bi-Sr-Rh-O, and q1 = - a* + 0.56b1* and q2 = 0.11b1* + 0.35c* for Bi-Ba-Rh-O, respectively, being the indications of (3+2) dimensional structures. High-resolution images taken with the incident electron beam parallel to the a- and c-axes clearly exhibit modulated atomic arrangements. These compounds are characterized by the displacement modulations in both RhO 2 layers and the RS-type blocks.

ホスト出版物のタイトルProceedings ICT'06 - 25th International Conference on Thermoelectrics
出版ステータスPublished - 2006 12月 1
イベントICT'06 - 25th International Conference on Thermoelectrics - Vienna, Austria
継続期間: 2006 8月 62006 8月 10


名前International Conference on Thermoelectrics, ICT, Proceedings


OtherICT'06 - 25th International Conference on Thermoelectrics

ASJC Scopus subject areas

  • 工学(全般)


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