Equivalent parameters for series thermoelectrics

We study the physical processes at work at the interface of two thermoelectric generators (TEGs) thermally and electrically connected in series. We show and explain how these processes impact on the system's performance: the derivation of the equivalent electrical series resistance yields a term whose physical meaning is thoroughly discussed. We demonstrate that this term must exist as a consequence of thermal continuity at the interface, since it is related to the variation of the junction temperature between the two TEGs associated in series as the electrical current varies. We then derive an expression for the equivalent series figure of merit. Finally we highlight the strong thermal/electrical symmetry between the parallel and series configurations and we compare our derivation with recent published results for the parallel configuration

Structure, electrical conductivity and electrochemical behavior of (La1-xSrx)2(Ni0.9Mn0.1)O4+δ based compounds

Solid oxide fuel cells typically operate at temperatures near 800 °C. One obstacle to reducing this temperature is finding a high-performance cathode for lower temperatures. La2NiO4+δ (LNO) has shown promise as a good material as a cathode being a well-known mixed electronic and ionic conductor. However, increasing the surface exchange in LNO is important for high performance applications. Mn substitution has been shown to increase the surface exchange of LNO with Sr required to stabilize the structure. Changing the ratio of Mn:Sr will change the oxidation state of Mn and Ni and the fundamental properties of the material. Changing the Sr content in (La1-xSrx)2(Ni0.9Mn0.1)O4+δ was investigated with x = 0.1-0.5. The XRD patterns shows a single phase K2NiF4 structures. Above 35% Sr the ‘a’ parameter of the unit cell starts increasing and the ‘c’ parameter starts to decrease. Increasing Sr content showed increased electrical conductivity from 40 S cm−1 to 261 S cm−1. Impedance data of the 10% Sr sample showed behavior similar to LNO sample with slightly increased area specific resistance (ASR); any further increase in Sr content further increases ASR of the electrode

Combined electronic and thermodynamic approaches for enhancing the thermoelectric properties of Ti-doped PbTe

DFT combined with statistical thermodynamics is used for investigating the effects of phase separation and impurity states on the electronic properties of Ti-doped PbTe.</p