TY - GEN
T1 - High-resolution electron microscopy of thermoelectric compounds Bi-(Sr,Ba)-Rh-O
AU - Yubuta, Kunio
AU - Okada, S.
AU - Miyazaki, Yuzuru
AU - Terasaki, I.
AU - Kajitani, T.
PY - 2006/12/1
Y1 - 2006/12/1
N2 -
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.
AB -
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.
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U2 - 10.1109/ICT.2006.331286
DO - 10.1109/ICT.2006.331286
M3 - Conference contribution
AN - SCOPUS:46149114418
SN - 1424408105
SN - 9781424408108
T3 - International Conference on Thermoelectrics, ICT, Proceedings
SP - 85
EP - 88
BT - Proceedings ICT'06 - 25th International Conference on Thermoelectrics
T2 - ICT'06 - 25th International Conference on Thermoelectrics
Y2 - 6 August 2006 through 10 August 2006
ER -