Carbon observation by electron energy-loss spectroscopy and thermoelectric properties of graphite added bismuth antimony telluride prepared by mechanical alloying-hot pressing

Kenji Hirota, Katsuhiro Takagi, Kenichi Hanasaku, Kana L. Hasezaki, Hikaru Saito, Satoshi Hata, Kazuhiro Hasezaki

Research output: Contribution to journalArticle

Abstract

The effects of additional graphite in (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x (x = 0, 0.004, 0.012, 0.032, 0.06, and 0.12) prepared by mechanical alloying followed by hot pressing were investigated. Carbon was added to obtain a low thermal conductivity via phonon scattering. The samples were examined by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and electron energy-loss spectroscopy (EELS). EELS can be used to investigate the distributions of light elements such as carbon. The diffraction peaks indicated a single-phase Bi 2 Te 3 –Sb 2 Te 3 solid solution. All the specimens were p-type semiconductors and SEM and TEM images showed dense without coarse grains. Agglomeration along the grain boundaries and inhomogeneous dispersion of carbon was observed by EELS. (Bi 0.3 Sb 1.7 Te 3.1 ) 0.88 C 0.12 grains wrapped by carbon layers of thickness approximately 50 nm were observed. The thermal conductivity of (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x increased with increasing x. It is considered that the presence of a large amount of carbon affected the thermal conductivity of the Bi 0.3 Sb 1.7 Te 3.1 matrix because the thermal conductivity of carbon is much higher than that of Bi 0.3 Sb 1.7 Te 3.1 and the carbon was dispersed inhomogeneously. Bi 0.3 Sb 1.7 Te 3.1 without additional graphite had a maximum dimensionless figure of merit ZT = 1.1. The ZT value decreased, and varied from 0.8 to 1.0, for (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x . The results show that inhomogeneously dispersed carbon did not improve the thermoelectric properties of Bi 0.3 Sb 1.7 Te 3.1 .

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalIntermetallics
Volume109
DOIs
Publication statusPublished - Jun 1 2019

Fingerprint

Antimony
Bismuth
Graphite
Electron energy loss spectroscopy
Mechanical alloying
Hot pressing
Carbon
Thermal conductivity
Transmission electron microscopy
Scanning electron microscopy
Phonon scattering
Chemical elements
Solid solutions
Grain boundaries
Agglomeration
Diffraction
Semiconductor materials
X ray diffraction

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

Cite this

Carbon observation by electron energy-loss spectroscopy and thermoelectric properties of graphite added bismuth antimony telluride prepared by mechanical alloying-hot pressing. / Hirota, Kenji; Takagi, Katsuhiro; Hanasaku, Kenichi; Hasezaki, Kana L.; Saito, Hikaru; Hata, Satoshi; Hasezaki, Kazuhiro.

In: Intermetallics, Vol. 109, 01.06.2019, p. 1-7.

Research output: Contribution to journalArticle

@article{fac5e41c11a84748af7d9a4ea6f357b5,
title = "Carbon observation by electron energy-loss spectroscopy and thermoelectric properties of graphite added bismuth antimony telluride prepared by mechanical alloying-hot pressing",
abstract = "The effects of additional graphite in (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x (x = 0, 0.004, 0.012, 0.032, 0.06, and 0.12) prepared by mechanical alloying followed by hot pressing were investigated. Carbon was added to obtain a low thermal conductivity via phonon scattering. The samples were examined by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and electron energy-loss spectroscopy (EELS). EELS can be used to investigate the distributions of light elements such as carbon. The diffraction peaks indicated a single-phase Bi 2 Te 3 –Sb 2 Te 3 solid solution. All the specimens were p-type semiconductors and SEM and TEM images showed dense without coarse grains. Agglomeration along the grain boundaries and inhomogeneous dispersion of carbon was observed by EELS. (Bi 0.3 Sb 1.7 Te 3.1 ) 0.88 C 0.12 grains wrapped by carbon layers of thickness approximately 50 nm were observed. The thermal conductivity of (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x increased with increasing x. It is considered that the presence of a large amount of carbon affected the thermal conductivity of the Bi 0.3 Sb 1.7 Te 3.1 matrix because the thermal conductivity of carbon is much higher than that of Bi 0.3 Sb 1.7 Te 3.1 and the carbon was dispersed inhomogeneously. Bi 0.3 Sb 1.7 Te 3.1 without additional graphite had a maximum dimensionless figure of merit ZT = 1.1. The ZT value decreased, and varied from 0.8 to 1.0, for (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x . The results show that inhomogeneously dispersed carbon did not improve the thermoelectric properties of Bi 0.3 Sb 1.7 Te 3.1 .",
author = "Kenji Hirota and Katsuhiro Takagi and Kenichi Hanasaku and Hasezaki, {Kana L.} and Hikaru Saito and Satoshi Hata and Kazuhiro Hasezaki",
year = "2019",
month = "6",
day = "1",
doi = "10.1016/j.intermet.2019.03.005",
language = "English",
volume = "109",
pages = "1--7",
journal = "Intermetallics",
issn = "0966-9795",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - Carbon observation by electron energy-loss spectroscopy and thermoelectric properties of graphite added bismuth antimony telluride prepared by mechanical alloying-hot pressing

AU - Hirota, Kenji

AU - Takagi, Katsuhiro

AU - Hanasaku, Kenichi

AU - Hasezaki, Kana L.

AU - Saito, Hikaru

AU - Hata, Satoshi

AU - Hasezaki, Kazuhiro

PY - 2019/6/1

Y1 - 2019/6/1

N2 - The effects of additional graphite in (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x (x = 0, 0.004, 0.012, 0.032, 0.06, and 0.12) prepared by mechanical alloying followed by hot pressing were investigated. Carbon was added to obtain a low thermal conductivity via phonon scattering. The samples were examined by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and electron energy-loss spectroscopy (EELS). EELS can be used to investigate the distributions of light elements such as carbon. The diffraction peaks indicated a single-phase Bi 2 Te 3 –Sb 2 Te 3 solid solution. All the specimens were p-type semiconductors and SEM and TEM images showed dense without coarse grains. Agglomeration along the grain boundaries and inhomogeneous dispersion of carbon was observed by EELS. (Bi 0.3 Sb 1.7 Te 3.1 ) 0.88 C 0.12 grains wrapped by carbon layers of thickness approximately 50 nm were observed. The thermal conductivity of (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x increased with increasing x. It is considered that the presence of a large amount of carbon affected the thermal conductivity of the Bi 0.3 Sb 1.7 Te 3.1 matrix because the thermal conductivity of carbon is much higher than that of Bi 0.3 Sb 1.7 Te 3.1 and the carbon was dispersed inhomogeneously. Bi 0.3 Sb 1.7 Te 3.1 without additional graphite had a maximum dimensionless figure of merit ZT = 1.1. The ZT value decreased, and varied from 0.8 to 1.0, for (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x . The results show that inhomogeneously dispersed carbon did not improve the thermoelectric properties of Bi 0.3 Sb 1.7 Te 3.1 .

AB - The effects of additional graphite in (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x (x = 0, 0.004, 0.012, 0.032, 0.06, and 0.12) prepared by mechanical alloying followed by hot pressing were investigated. Carbon was added to obtain a low thermal conductivity via phonon scattering. The samples were examined by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and electron energy-loss spectroscopy (EELS). EELS can be used to investigate the distributions of light elements such as carbon. The diffraction peaks indicated a single-phase Bi 2 Te 3 –Sb 2 Te 3 solid solution. All the specimens were p-type semiconductors and SEM and TEM images showed dense without coarse grains. Agglomeration along the grain boundaries and inhomogeneous dispersion of carbon was observed by EELS. (Bi 0.3 Sb 1.7 Te 3.1 ) 0.88 C 0.12 grains wrapped by carbon layers of thickness approximately 50 nm were observed. The thermal conductivity of (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x increased with increasing x. It is considered that the presence of a large amount of carbon affected the thermal conductivity of the Bi 0.3 Sb 1.7 Te 3.1 matrix because the thermal conductivity of carbon is much higher than that of Bi 0.3 Sb 1.7 Te 3.1 and the carbon was dispersed inhomogeneously. Bi 0.3 Sb 1.7 Te 3.1 without additional graphite had a maximum dimensionless figure of merit ZT = 1.1. The ZT value decreased, and varied from 0.8 to 1.0, for (Bi 0.3 Sb 1.7 Te 3.1 ) 1−x C x . The results show that inhomogeneously dispersed carbon did not improve the thermoelectric properties of Bi 0.3 Sb 1.7 Te 3.1 .

UR - http://www.scopus.com/inward/record.url?scp=85062462345&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85062462345&partnerID=8YFLogxK

U2 - 10.1016/j.intermet.2019.03.005

DO - 10.1016/j.intermet.2019.03.005

M3 - Article

VL - 109

SP - 1

EP - 7

JO - Intermetallics

JF - Intermetallics

SN - 0966-9795

ER -