TY - GEN

T1 - Structural, magnetic and thermoelectric properties of Delafossite-type oxide, CuCr1-xMgxO2(0 ≤ × ≤ 0.05)

AU - Ono, Yasuhiro

AU - Satoh, Ken Ichi

AU - Nozaki, Tomohiro

AU - Kajitani, Tsuyoshi

PY - 2006/12/1

Y1 - 2006/12/1

N2 - We report structural, magnetic and high-temperature thermoelectric properties of Delafossite-type oxide, CuCr1-xMgxO 2 (0≤×0.05). Lattice parameter, c, linearly decreases with increasing Mg concentration in the range, 0≤ × <0.03. This decrease is mainly caused by the shrinking of O-Cu-O dumbbells which connect the CdI 2-type (Cr/Mg)O2 slabs. Magnetic susceptibility measurements indicate that Cr3+ is in the high spin state in the paramagnetic phase above 25 K. Electrical resistivity, ρ, of CuCr 1-xMgxO2 exhibits semiconducting behavior (dp/dT<0) in the range from 350 K to 1100 K and becomes lower through the partial substitution of Mg2+ for Cr3+ in 0≤×≤0.03. Due to positive Seebeck coefficients, S, of these oxides, it is natural to assume that the dominant charge carriers of CuCr 1-xMgxO2 are positive holes. Experimental values of Sat 1100 K have consistency with the theoretical values predicted from Koshibae's formula. From the linear S vs. lnσ plot, it is estimated that the observed power factor, S2σ, reaches the maximum value around x=0.03 in this system. The thermal conductivity, Κ, for CuCr 1-xMgxO2 ranges from 6 to 10 W·m -1·K-1 at 300 K. The maximum dimensionless figure of merit, ZT=S2T/ρΚ, of the sample with x=0.03 is 0.04 at 950 K.

AB - We report structural, magnetic and high-temperature thermoelectric properties of Delafossite-type oxide, CuCr1-xMgxO 2 (0≤×0.05). Lattice parameter, c, linearly decreases with increasing Mg concentration in the range, 0≤ × <0.03. This decrease is mainly caused by the shrinking of O-Cu-O dumbbells which connect the CdI 2-type (Cr/Mg)O2 slabs. Magnetic susceptibility measurements indicate that Cr3+ is in the high spin state in the paramagnetic phase above 25 K. Electrical resistivity, ρ, of CuCr 1-xMgxO2 exhibits semiconducting behavior (dp/dT<0) in the range from 350 K to 1100 K and becomes lower through the partial substitution of Mg2+ for Cr3+ in 0≤×≤0.03. Due to positive Seebeck coefficients, S, of these oxides, it is natural to assume that the dominant charge carriers of CuCr 1-xMgxO2 are positive holes. Experimental values of Sat 1100 K have consistency with the theoretical values predicted from Koshibae's formula. From the linear S vs. lnσ plot, it is estimated that the observed power factor, S2σ, reaches the maximum value around x=0.03 in this system. The thermal conductivity, Κ, for CuCr 1-xMgxO2 ranges from 6 to 10 W·m -1·K-1 at 300 K. The maximum dimensionless figure of merit, ZT=S2T/ρΚ, of the sample with x=0.03 is 0.04 at 950 K.

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U2 - 10.1109/ICT.2006.331288

DO - 10.1109/ICT.2006.331288

M3 - Conference contribution

AN - SCOPUS:46149125758

SN - 1424408105

SN - 9781424408108

T3 - International Conference on Thermoelectrics, ICT, Proceedings

SP - 92

EP - 96

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 -