Effects of Ni, Pd and Pt substitutions on thermoelectric properties of cosi alloys

Hui Sun, Xu Lu, Donald T. Morelli

Research output: Contribution to journalArticle

  • 9 Citations

Abstract

Ni-, Pd- and Pt-substituted CoSi samples have been prepared by an arc melting and annealing procedure. The x-ray diffraction and scanning electron microscopy results show that Ni and Pd are effective n-type dopants for CoSi, while Pt is immiscible with CoSi and forms an impurity phase with a possible chemical formula of PtCoSi2. The thermoelectric properties were measured from 80 K to 300 K. For Ni- and Pd-doped samples, the electrical resistivity and Seebeck coefficient decrease simultaneously due to the increasing carrier concentration. For Pt-substituted samples, the electrical resistivity also decreases. However, this reduction is thought to be not due to an increase in carriers but rather to originate from the effect of the Pt-rich impurity phase at the grain boundaries. The Seebeck coefficient is not affected by 1% Pt substitution; however, further increase of the Pt level also causes a decrease in the Seebeck coefficient. The room-temperature power factor is 63 μW K-2 cm-1 for pure CoSi and 73 μW K-2 cm-1 for the Co0.99Pt0.01Si sample. Although the thermal conductivity is reduced for both n-type-doped and Pt-substituted samples around 80 K, the room-temperature values are still close to that of pure CoSi. As a result, ZT of 0.13 is obtained at room temperature for Co 0.99Pt0.01Si, an 18% increase compared with CoSi.

LanguageEnglish (US)
Pages1352-1357
Number of pages6
JournalJournal of Electronic Materials
Volume42
Issue number7
DOIs
StatePublished - Jul 2013

Profile

Seebeck coefficient
Substitution reactions
substitutes
Seebeck effect
Impurities
room temperature
Temperature
Carrier concentration
Thermal conductivity
Grain boundaries
Melting
Diffraction
impurities
arc melting
Doping (additives)
electrical resistivity
Annealing
X rays
Scanning electron microscopy
x ray diffraction

Keywords

  • CoSi
  • impurity phase
  • Ni doping
  • Pd doping
  • Pt substitution
  • thermoelectric properties

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Materials Chemistry

Cite this

Effects of Ni, Pd and Pt substitutions on thermoelectric properties of cosi alloys. / Sun, Hui; Lu, Xu; Morelli, Donald T.

In: Journal of Electronic Materials, Vol. 42, No. 7, 07.2013, p. 1352-1357.

Research output: Contribution to journalArticle

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abstract = "Ni-, Pd- and Pt-substituted CoSi samples have been prepared by an arc melting and annealing procedure. The x-ray diffraction and scanning electron microscopy results show that Ni and Pd are effective n-type dopants for CoSi, while Pt is immiscible with CoSi and forms an impurity phase with a possible chemical formula of PtCoSi2. The thermoelectric properties were measured from 80 K to 300 K. For Ni- and Pd-doped samples, the electrical resistivity and Seebeck coefficient decrease simultaneously due to the increasing carrier concentration. For Pt-substituted samples, the electrical resistivity also decreases. However, this reduction is thought to be not due to an increase in carriers but rather to originate from the effect of the Pt-rich impurity phase at the grain boundaries. The Seebeck coefficient is not affected by 1{\%} Pt substitution; however, further increase of the Pt level also causes a decrease in the Seebeck coefficient. The room-temperature power factor is 63 μW K-2 cm-1 for pure CoSi and 73 μW K-2 cm-1 for the Co0.99Pt0.01Si sample. Although the thermal conductivity is reduced for both n-type-doped and Pt-substituted samples around 80 K, the room-temperature values are still close to that of pure CoSi. As a result, ZT of 0.13 is obtained at room temperature for Co 0.99Pt0.01Si, an 18{\%} increase compared with CoSi.",
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N2 - Ni-, Pd- and Pt-substituted CoSi samples have been prepared by an arc melting and annealing procedure. The x-ray diffraction and scanning electron microscopy results show that Ni and Pd are effective n-type dopants for CoSi, while Pt is immiscible with CoSi and forms an impurity phase with a possible chemical formula of PtCoSi2. The thermoelectric properties were measured from 80 K to 300 K. For Ni- and Pd-doped samples, the electrical resistivity and Seebeck coefficient decrease simultaneously due to the increasing carrier concentration. For Pt-substituted samples, the electrical resistivity also decreases. However, this reduction is thought to be not due to an increase in carriers but rather to originate from the effect of the Pt-rich impurity phase at the grain boundaries. The Seebeck coefficient is not affected by 1% Pt substitution; however, further increase of the Pt level also causes a decrease in the Seebeck coefficient. The room-temperature power factor is 63 μW K-2 cm-1 for pure CoSi and 73 μW K-2 cm-1 for the Co0.99Pt0.01Si sample. Although the thermal conductivity is reduced for both n-type-doped and Pt-substituted samples around 80 K, the room-temperature values are still close to that of pure CoSi. As a result, ZT of 0.13 is obtained at room temperature for Co 0.99Pt0.01Si, an 18% increase compared with CoSi.

AB - Ni-, Pd- and Pt-substituted CoSi samples have been prepared by an arc melting and annealing procedure. The x-ray diffraction and scanning electron microscopy results show that Ni and Pd are effective n-type dopants for CoSi, while Pt is immiscible with CoSi and forms an impurity phase with a possible chemical formula of PtCoSi2. The thermoelectric properties were measured from 80 K to 300 K. For Ni- and Pd-doped samples, the electrical resistivity and Seebeck coefficient decrease simultaneously due to the increasing carrier concentration. For Pt-substituted samples, the electrical resistivity also decreases. However, this reduction is thought to be not due to an increase in carriers but rather to originate from the effect of the Pt-rich impurity phase at the grain boundaries. The Seebeck coefficient is not affected by 1% Pt substitution; however, further increase of the Pt level also causes a decrease in the Seebeck coefficient. The room-temperature power factor is 63 μW K-2 cm-1 for pure CoSi and 73 μW K-2 cm-1 for the Co0.99Pt0.01Si sample. Although the thermal conductivity is reduced for both n-type-doped and Pt-substituted samples around 80 K, the room-temperature values are still close to that of pure CoSi. As a result, ZT of 0.13 is obtained at room temperature for Co 0.99Pt0.01Si, an 18% increase compared with CoSi.

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