Abstract
Ruddlesden-Popper (RP) phase (Sr0.9La0.1)3Ti2O7/xAg (x=0, 0.05, 0.10, 0.15) are systematically investigated with regard to their phase composition and thermoelectric transport properties. The XRD results show that all oxide samples are of two phases and they have layered microstructure. The electrical conductivity is found to be increased simultaneously. And the absolute Seebeck coefficient decreases firstly and then increases Ag addition, which leads to (Sr0.9La0.1)3Ti2O7/xAg (x=0.10) sample possesses optimum power factor. The total thermal conductivity lowers with Ag addition. The dimensionless figure of merit, ZT, reaches 0.12 for x=0.10. These results suggest that a proper of metal element Ag addition would be an effective way improving thermoelectric performance of (Sr0.9La0.1)3Ti2O7 system.
Highlights
Thermoelectric materials have been attracted much attention for which can convert thermal energy to electrical energy [1–3]
The electrical conductivity increases slightly with increasing Ag addition content, the same phenomena has been observed in the Ag added in Ca3Co4O9+δ ceramic [16]
Ag addition causes an increase in carrier concentration, and, on the other hand, Ag can act as electrical connections between (Sr0.9La0.1)3Ti2O7 grains
Summary
Thermoelectric materials have been attracted much attention for which can convert thermal energy to electrical energy [1–3]. Lanthanum doped SrTiO3 single crystal exhibits high power factor comparable with that of Bi-Te alloy at room temperature [8, 9] Their thermoelectric performance is still low due to the fact that the κ value of SrTiO3 bulk crystal (∼12 W/mK) [10] at room temperature is approximately one order of magnitude larger than that of Bi2Te3 [8]. According to the reference [15], in the semiconducting matrix, metallic addition induces band bending which creates a potential barrier Such a barrier acts as an energy filter from which low-energy electrons are strongly scattered, while high-energy electrons remain almost unaffected. This filtering effect increases the mean energy per carrier resulting in the Seebeck coefficient larger Encouraged by these results, we attempt to improve the thermoelectric performance for the Ruddlesden-Popper phases (Sr0.9La0.1)3Ti2O7 ceramic by Ag addition. Thermoelectric properties have been measured in temperature range from 250 K to 1050 K, and the effects of Ag addition on thermoelectric properties (Sr0.9La0.1)3Ti2O7 ceramic have been discussed
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