多結晶Ba₈Au_xSi_46−xクラスレートを用いた温度差を必要としない新規熱－電力変換材料の開発

抄録

Poly-crystalline Ba₈Au_xSi_46−x clathrate with p-n junction was synthesized for electric power generation from heat under no temperature difference. The n-type Ba₈Au_4.5Si_41.5 and the p-type Ba₈Au_5.5Si_40.5 powder were stacked in the graphite die and sintered by a Spark Plasma Sintering (SPS) method at 1073 K for 5 min with pressure of 50 MPa. The Au composition of Ba₈Au_4.5Si_41.5 and Ba₈Au_5.5Si_40.5 side in the sintered sample were Ba_7.8Au_4.2Si_41.8 and Ba_7.8Au_5.2Si_40.8, respectively. It was found that the Au composition was gradually changed near the interface with thickness of around 500 micrometers. Electric power generation test under no temperature difference was performed by using the sample cut to contain the interface of two layers. The electric power increased by only heating and the maximum voltage can be observed around 2 mV at 773 K. These results suggested that electron excitation occurred near the n/p interface and generated electrons and holes diffuse to n-type and p-type semiconductor side, respectively.