09:30 〜 09:45
▼ [13a-2T-3] Thermoelectric properties of bulk β-Indium sulfide with Mg doping
キーワード：thermoelectric,sulfide
Abstract
An ab initio calculation indicated that the low temperature phase of indium sulfide, β-In2S3 has a potential to be good thermoelectric materials. The thermoelectric properties of Mg-doped β-In2S3 above room temperature were investigated at the first time.
The bulk samples of In2-xMgxS3 (x =0, 0.05, 0.1, 0.2 and 0.3) were prepared by pulsed current sintering using the powder obtained from the solid reaction of raw elements in a sealed silica tube. All bulk samples showed high relative density over than 90%. The powder X-ray diffraction (XRD) patterns of all samples were well indexed as β-In2S3 structure without any second phases. The peaks shift to the lower diffraction angles indicating the increasing of lattice parameter of magnesium-substituted samples. This result sounds strange because ionic radius of magnesium is smaller than indium, and presumably indicates the simultaneous formation of vacancies on magnesium-substitution.
The thermoelectric properties of Seebeck coefficient (S), electrical resistivity (ρ), and thermal conductivity (κ) were measured at temperature range from 300 K to 700 K. The maximum power factor (S2/ρ) for non-doped In2S3 is 426.5 μW/mK2, which was slightly higher than that of magnesium substituted samples at the same temperature. On the other hand, the thermal conductivity κ at 300 K significantly decreased from 1.64W/mK for the non-doped sample to 1.10 W/mK for the sample with x = 0.2. The reduction in κ may attribute to the increasing of point defect scatting caused by the anharmonic oscillation of atoms in the vicinity of vacancies. The maximum dimensionless figure of merit ZT = S2T/ρκ for non-doped In2S3 and magnesium doped sample (x = 0.1) were 0.38 and 0.45 at 700 K, respectively.
An ab initio calculation indicated that the low temperature phase of indium sulfide, β-In2S3 has a potential to be good thermoelectric materials. The thermoelectric properties of Mg-doped β-In2S3 above room temperature were investigated at the first time.
The bulk samples of In2-xMgxS3 (x =0, 0.05, 0.1, 0.2 and 0.3) were prepared by pulsed current sintering using the powder obtained from the solid reaction of raw elements in a sealed silica tube. All bulk samples showed high relative density over than 90%. The powder X-ray diffraction (XRD) patterns of all samples were well indexed as β-In2S3 structure without any second phases. The peaks shift to the lower diffraction angles indicating the increasing of lattice parameter of magnesium-substituted samples. This result sounds strange because ionic radius of magnesium is smaller than indium, and presumably indicates the simultaneous formation of vacancies on magnesium-substitution.
The thermoelectric properties of Seebeck coefficient (S), electrical resistivity (ρ), and thermal conductivity (κ) were measured at temperature range from 300 K to 700 K. The maximum power factor (S2/ρ) for non-doped In2S3 is 426.5 μW/mK2, which was slightly higher than that of magnesium substituted samples at the same temperature. On the other hand, the thermal conductivity κ at 300 K significantly decreased from 1.64W/mK for the non-doped sample to 1.10 W/mK for the sample with x = 0.2. The reduction in κ may attribute to the increasing of point defect scatting caused by the anharmonic oscillation of atoms in the vicinity of vacancies. The maximum dimensionless figure of merit ZT = S2T/ρκ for non-doped In2S3 and magnesium doped sample (x = 0.1) were 0.38 and 0.45 at 700 K, respectively.