Terbium Ion Doping in Ca3Co4O9: A Step towards High-Performance Thermoelectric Materials

Abstract

The potential of thermoelectric materials to generate electricity from the waste heat can play a key role in achieving a global sustainable energy future. In order to proceed in this direction, it is essential to have thermoelectric materials that are environmentally friendly and exhibit high figure of merit, ZT. Oxide thermoelectric materials are considered ideal for such applications. High thermoelectric performance has been reported in single crystals of Ca3Co4O9. However, for large scale applications single crystals are not suitable and it is essential to develop high-performance polycrystalline thermoelectric materials. In polycrystalline form, Ca3Co4O9 is known to exhibit much weaker thermoelectric response than in single crystal form. Here, we report the observation of enhanced thermoelectric response in polycrystalline Ca3Co4O9 on doping Tb ions in the material. Polycrystalline Ca3−xTbxCo4O9 (x = 0.0–0.7) samples were prepared by a solid-state reaction technique. Samples were thoroughly characterized using several state of the art techniques including XRD, TEM, SEM and XPS. Temperature dependent Seebeck coefficient, electrical resistivity and thermal conductivity measurements were performed. A record ZT of 0.74 at 800 K was observed for Tb doped Ca3Co4O9 which is the highest value observed till date in any polycrystalline sample of this system.

Nanostructural Tailoring to Induce Flexibility in Thermoelectric Ca3Co4O9 Thin Films

“…52 Near room temperature, the power factor of the flexible film ( T s : 675 °C) is comparable to the values reported for undoped bulk polycrystalline Ca 3 Co 4 O 9 , 49−52 and further enhancement of power factor of the film is possible by optimal doping. 53,54 …”

Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics

“…Further enhancement of the power factor is still possible by doping. 18,50−52 With this power factor combined with transferability, the nanoporous Ca 3 Co 4 O 9 films are candidates for near-room-temperature thermoelectric applications.…”

Effective Schottky barrier lowering of NiGe/p-Ge(100) using Terbium interlayer structure for high performance p-type MOSFETs

“…In the case of Ni 2p3/2 the peak intensity increase, is due to higher exposed Ni surface area and increase in the nearest Ni-Ni distance due to insertion of Tb as previously reported 37,38 . Also chemical state of Tb in the NiGe-Tb alloy could be +3, +4 corresponding to Tb 4d peak according to pervious studied 39,40 . However we notice high background noise with no characteristic Tb 4d peaks was observed in the XPS spectrum, which could be due to low concentration of Tb in the sample.…”