11:30 〜 11:45
▲ [21a-W323-8] Enhancement of power factor by energy filtering effect in Re substituted HMS
キーワード：thermoelectric materials,silicide,energy filtering effect
The higher manganese silicide (HMS) is an promising thermoelectric material, as it is nontoxic, cheap and it possess large Seebeck coefficient 200mVK-1 with metallic electrical connectivity 2 mWcm. The reported Re substituted HMS shows ZT=1.04 at 900K which is due to substantial reduction in lattice thermal conductivity [1]. On the other hand, the power factor of HMS can be enhanced by introducing energy filtering effect by grain boundaries [2]. Thus, in this study we combined both mechanisms: 1) reduction of lattice thermal conductivity by Re substitution and 2) energy filtering effect by grain boundaries to obtain high performance HMS.
We prepared (Mn30.6Re6Si63.4) by melting high purity Mn, Si, and Re elements in arc-melting furnace followed by Liquid quenching (LQ) technique, where the molten alloy was injected on a copper wheel of 200mm diameter and rotating at ~4500 rpm. All the above processes were carried out under pressurized argon atmosphere. The ribbon samples were annealed and then sintered by spark plasma sintering.
The structural and transport properties were analyzed for three different samples: 1) Non-annealed LQ ribbons, 2) Annealed LQ ribbons and 3) Sintered pellet. The powder XRD and SEM data confirms process dependent structural evolution of Re-HMS, the LQ samples show very fine grains (500nm) and coarse grains (8mm) for SPS samples. The Seebeck coefficient show 30-40% improvement in LQ samples compared to SPS sample, which eventually improves power factor by ~35%. The results suggest successful implementation of energy filtering effect in high ZT Re substituted HMS. Further, the detailed analysis of microstructure and transport properties will be shown in presentation.
1. A. Yamamoto, S. Ghodke et al. “Thermoelectric poperties of super-saturated Re solid solution of higher manganese silicides” Jpn. J. Appl. Phys. (2016) in press
2. S. Ghodke et al., CMCEE-11, American ceramic society, 14-20 June 2015.(Proceedings)
We prepared (Mn30.6Re6Si63.4) by melting high purity Mn, Si, and Re elements in arc-melting furnace followed by Liquid quenching (LQ) technique, where the molten alloy was injected on a copper wheel of 200mm diameter and rotating at ~4500 rpm. All the above processes were carried out under pressurized argon atmosphere. The ribbon samples were annealed and then sintered by spark plasma sintering.
The structural and transport properties were analyzed for three different samples: 1) Non-annealed LQ ribbons, 2) Annealed LQ ribbons and 3) Sintered pellet. The powder XRD and SEM data confirms process dependent structural evolution of Re-HMS, the LQ samples show very fine grains (500nm) and coarse grains (8mm) for SPS samples. The Seebeck coefficient show 30-40% improvement in LQ samples compared to SPS sample, which eventually improves power factor by ~35%. The results suggest successful implementation of energy filtering effect in high ZT Re substituted HMS. Further, the detailed analysis of microstructure and transport properties will be shown in presentation.
1. A. Yamamoto, S. Ghodke et al. “Thermoelectric poperties of super-saturated Re solid solution of higher manganese silicides” Jpn. J. Appl. Phys. (2016) in press
2. S. Ghodke et al., CMCEE-11, American ceramic society, 14-20 June 2015.(Proceedings)