Thermoelectric properties of Ca-Ir-O compounds prepared by spark plasma sintering

Nittaya Keawprak; Rong Tu; Takashi Goto

doi:10.2320/matertrans.MRA2008377

Thermoelectric properties of Ca-Ir-O compounds prepared by spark plasma sintering

Nittaya Keawprak, Rong Tu, Takashi Goto

Materials Processing and Characterization Division

Research output: Contribution to journal › Article › peer-review

5 Citations (Scopus)

Abstract

Ca-Ir-O Compounds in various molar ratios of Ir to Ca (R_Ir/Ca) from 0.2 to 1.2 were synthesized by solid-state reaction and compacted by spark plasma sintering (SPS). Ca₄IrO₆ and CaIrO₃ with a small amount of second phase were obtained at R_Ir/Ca = 0.25 and 1.0, respectively, whereas Ca₂IrO₄ in a single phase was obtained at R_Ir/Ca = 0.5. The electrical conductivity was 4 × 10^-4 to 150 Sm^-1 at room temperature and exhibited a semiconducting behavior for all the samples. The Seebeck coefficient at R _Ir/Ca = 0.4 to 0.7 showed negative values whereas samples with R _Ir/Ca = 0.25 and 0.9 to 1.2 showed positive values. The thermal conductivity was 1.1 to 2.7 Wm^-1K^-1 at room temperature and slightly decreased with increasing temperature. The highest ZT value of p-type was 0.006 at 1023 K and R_Ir/Ca = 11 and 1.2, while that of n-type was 0.0022 at 800 K and R_Ir/Ca = 0.5.

Original language	English
Pages (from-to)	853-858
Number of pages	6
Journal	Materials Transactions
Volume	50
Issue number	4
DOIs	https://doi.org/10.2320/matertrans.MRA2008377
Publication status	Published - 2009 Apr

Keywords

Calcium iridium oxide
Spark plasma sintering
Thermoelectric materials

ASJC Scopus subject areas

Materials Science(all)
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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10.2320/matertrans.MRA2008377

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title = "Thermoelectric properties of Ca-Ir-O compounds prepared by spark plasma sintering",

abstract = "Ca-Ir-O Compounds in various molar ratios of Ir to Ca (RIr/Ca) from 0.2 to 1.2 were synthesized by solid-state reaction and compacted by spark plasma sintering (SPS). Ca4IrO6 and CaIrO3 with a small amount of second phase were obtained at RIr/Ca = 0.25 and 1.0, respectively, whereas Ca2IrO4 in a single phase was obtained at RIr/Ca = 0.5. The electrical conductivity was 4 × 10-4 to 150 Sm-1 at room temperature and exhibited a semiconducting behavior for all the samples. The Seebeck coefficient at R Ir/Ca = 0.4 to 0.7 showed negative values whereas samples with R Ir/Ca = 0.25 and 0.9 to 1.2 showed positive values. The thermal conductivity was 1.1 to 2.7 Wm-1K-1 at room temperature and slightly decreased with increasing temperature. The highest ZT value of p-type was 0.006 at 1023 K and RIr/Ca = 11 and 1.2, while that of n-type was 0.0022 at 800 K and RIr/Ca = 0.5.",

keywords = "Calcium iridium oxide, Spark plasma sintering, Thermoelectric materials",

author = "Nittaya Keawprak and Rong Tu and Takashi Goto",

year = "2009",

month = apr,

doi = "10.2320/matertrans.MRA2008377",

language = "English",

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pages = "853--858",

journal = "Materials Transactions",

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T1 - Thermoelectric properties of Ca-Ir-O compounds prepared by spark plasma sintering

AU - Keawprak, Nittaya

AU - Tu, Rong

AU - Goto, Takashi

PY - 2009/4

Y1 - 2009/4

N2 - Ca-Ir-O Compounds in various molar ratios of Ir to Ca (RIr/Ca) from 0.2 to 1.2 were synthesized by solid-state reaction and compacted by spark plasma sintering (SPS). Ca4IrO6 and CaIrO3 with a small amount of second phase were obtained at RIr/Ca = 0.25 and 1.0, respectively, whereas Ca2IrO4 in a single phase was obtained at RIr/Ca = 0.5. The electrical conductivity was 4 × 10-4 to 150 Sm-1 at room temperature and exhibited a semiconducting behavior for all the samples. The Seebeck coefficient at R Ir/Ca = 0.4 to 0.7 showed negative values whereas samples with R Ir/Ca = 0.25 and 0.9 to 1.2 showed positive values. The thermal conductivity was 1.1 to 2.7 Wm-1K-1 at room temperature and slightly decreased with increasing temperature. The highest ZT value of p-type was 0.006 at 1023 K and RIr/Ca = 11 and 1.2, while that of n-type was 0.0022 at 800 K and RIr/Ca = 0.5.

AB - Ca-Ir-O Compounds in various molar ratios of Ir to Ca (RIr/Ca) from 0.2 to 1.2 were synthesized by solid-state reaction and compacted by spark plasma sintering (SPS). Ca4IrO6 and CaIrO3 with a small amount of second phase were obtained at RIr/Ca = 0.25 and 1.0, respectively, whereas Ca2IrO4 in a single phase was obtained at RIr/Ca = 0.5. The electrical conductivity was 4 × 10-4 to 150 Sm-1 at room temperature and exhibited a semiconducting behavior for all the samples. The Seebeck coefficient at R Ir/Ca = 0.4 to 0.7 showed negative values whereas samples with R Ir/Ca = 0.25 and 0.9 to 1.2 showed positive values. The thermal conductivity was 1.1 to 2.7 Wm-1K-1 at room temperature and slightly decreased with increasing temperature. The highest ZT value of p-type was 0.006 at 1023 K and RIr/Ca = 11 and 1.2, while that of n-type was 0.0022 at 800 K and RIr/Ca = 0.5.

KW - Calcium iridium oxide

KW - Spark plasma sintering

KW - Thermoelectric materials

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JF - Materials Transactions

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Thermoelectric properties of Ca-Ir-O compounds prepared by spark plasma sintering

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