High temperature thermoelectric characteristics of Ca0.9R0.1MnO3 (R=La,Pr,…,Yb)

Abstract

Electron-doped perovskite manganite Ca0.9R0.1MnO3 (R=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) polycrystalline samples were prepared and their transport and thermoelectric properties were studied from room temperature to 1000 K. The transport behavior for all the samples is adiabatic small polaron hopping mechanism below 600 K but changes to metallic conductivity at higher temperature. Above 600 K, more 3d electrons of Mn3+ ions will occupy eg orbitals, resulting in the variation in thermoelectric power values. For all the samples, thermoelectric power is only determined by carrier concentration, but resistivity also rests with effective bandwidth. The size matching between Ca2+ and R3+ ions together with heavier R3+ doping can improve thermoelectric performance evidently. Combining these two factors, Ca0.9Dy0.1MnO3 and Ca0.9Yb0.1MnO3 reach ZT=0.2 at 1000 K, suggesting that they can be efficient high temperature n-type thermoelectric oxide materials.

Thermoelectric and thermal transport properties of complex oxide thin films, heterostructures and superlattices

“…151,152 Interestingly, the idea of electron filtering to improve thermoelectric properties of superlattices was studied in the model system La 0. 67 …”

Half-metallic perovskite superlattices with colossal thermoelectric figure of merit

“…However, the room temperature gure of merit is usually low. For example, for NaCo 2 18) a value of 0.11 at high Na doping. Good oxide thermoelectrics at room temperature and elevated temperatures as well as understanding of the mechanisms leading to such properties therefore are highly desirable.…”

“…Efficient thermoelectric materials [2][3][4][5][6] have to show a high thermoelectric gure of merit Z ¼ S 2 s/k, where S, s, and k denote the Seebeck coefficient, electrical conductivity, and thermal conductivity, respectively. On the other hand, the power factor S 2 s focuses on the behavior of the electrons when thermal conductivity can be ruled out at the two end reservoirs.…”

High-temperature thermoelectric properties of Ca0.9Y0.1Mn1−x Fe x O3 (0 ≤ x ≤ 0.25)

“…Many attempts have been 54 made in order to improve the thermoelectric performance 55 of this type of material, mainly to enhance the electrical 56 conductivity, reduce further the thermal conductivity, 57 while avoiding degradation of the Seebeck coefficient. 58 Most of these studies have been focused on doping, for 59 example, Yb at Ca-site [4][5][6][7] or Nb at Mn-site [3,8], while 60 only few reports performed the research on dually doping, 61 e.g., Sr and Yb at Ca-site [9]. Previous reports have showed 62 that the substitution of Y for Ca resulted in a significant 63 improvement in the thermoelectric performance of Ca 12x 64 Y x MnO 3 system in a wide temperature region, and the 87 (99.9 %) precursors were thoroughly mixed by ball milling 88 with ethanol for 24 h. The mixtures were dried and then 89 calcined at 1273 K for 24 h in air with an intermediate 90 grinding procedure.…”

“…For 48 this purpose, metal oxide-based materials are considered as 49 good candidates. 50 CaMnO 3 , which is a perovskite oxide with orthorhombic 51 structure at room temperature, has also been considered as 52 a promising thermoelectric n-type material for high-53 temperature application [3][4][5][6][7][8][9]. Many attempts have been 54 made in order to improve the thermoelectric performance 55 of this type of material, mainly to enhance the electrical 56 conductivity, reduce further the thermal conductivity, 57 while avoiding degradation of the Seebeck coefficient.…”