Effects of Ga content on thermoelectric properties of P-type Ba8Ga16+xZn3Ge27−x type-I clathrates
2009
Deng, Shu-kang | Tang, Xin-feng | Yang, Pei-zhi | Li, Ming
P-type Ba₈Ga₁₆₊ₓZn₃Ge₂₇₋ₓ (x = 0.1, 0.2, 0.3, and 0.4) type-I clathrates were synthesized by combining solid-state reaction with spark plasma sintering (SPS) technology. The effects of slight increase of Ga content on thermoelectric properties have been investigated. The results show that at room temperature the carrier concentration Nₚ of p-type Ba₈Ga₁₆₊ₓZn₃Ge₂₇₋ₓ clathrates increases remarkably compared with that of Ba₈Ga₁₆Zn₃Ge₂₇ compound, which results in the increases of electrical conductivity although carrier mobility μH slightly decreases. The thermal conductivity κ of all samples increases with the increase of Ga content. Ba₈Ga₁₆.₂Zn₃Ge₂₆.₈ compound exhibits the highest ZT value of 0.43 at 700 K, which is increased by 13% compared with that of Ba₈Ga₁₆Zn₃Ge₂₇ compound.
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