Academic Journal
Enhancing the Thermoelectric Performance of Calcium Cobaltite Ca3Co4O9 through Single and Dual Elements Doping
| العنوان: | Enhancing the Thermoelectric Performance of Calcium Cobaltite Ca3Co4O9 through Single and Dual Elements Doping |
|---|---|
| المؤلفون: | Romo de la Cruz, Cesar Octavio |
| المصدر: | Graduate Theses, Dissertations, and Problem Reports |
| بيانات النشر: | The Research Repository @ WVU |
| سنة النشر: | 2019 |
| المجموعة: | The Research Repository @ WVU (West Virginia University) |
| مصطلحات موضوعية: | Calcium cobalt oxide, thermoelectric materials, grain boundaries, nanostructure, Ceramic Materials |
| الوصف: | Worldwide energy consumption losses more than 60% of the energy after its conversion, most of these losses are in the form of waste heat. Therefore, it is a matter of utmost importance to harness waste heat and reutilize this energy source to improve the overall conversion efficiency. Thermoelectric (TE) technology is one of the rising alternatives to harvest the excessive amount of energy lost as waste heat for a better and sustainable energy future. TE materials can utilize waste heat to improve efficiency in the ever-increasing demand for energy by converting a temperature difference directly into electricity due to the Seebeck effect. The energy conversion efficiency of TE materials is described by the figure of merit ZT, which is defined as ZT= S2ρ‑1κ‑1T, where S, ρ, S2ρ-1, and κ are the Seebeck coefficient, electrical resistivity, electrical power factor(PF) and thermal conductivity, respectively. P-type calcium cobaltite Ca3Co4O9-δ is a promising candidate for TE applications over conventional TE materials due to its high thermal stability in the air at high temperatures, low cost, lightweight, and non-toxicity. Single crystal Ca3Co4O9-δ already possess an excellent TE performance, approaching that of the well-developed conventional TE materials. However, TE energy conversion efficiency of polycrystalline Ca3Co4O9-δ remains low and accounts to ~30-60% of the single crystals. To overcome the low performance of the ZT in Ca3Co4O9-δ ceramics, dopants were introduced through both the cation stoichiometric substitution and novel non-stoichiometric addition. This thesis work shows that dopants intragranular non-stoichiometric addition and concurrent intergranular segregation at the grain boundaries dramatically decrease the electrical resistivity, simultaneously increase the Seebeck coefficient, and ultimately result in the polycrystalline ceramics outperforming the single crystals over a wide range of temperatures. A record high thermoelectric figure of merit ZT~0.9 at 1073 K was achieved for Ca3Co4O9‑δ ... |
| نوع الوثيقة: | text |
| وصف الملف: | application/pdf |
| اللغة: | unknown |
| Relation: | https://researchrepository.wvu.edu/etd/7396; https://researchrepository.wvu.edu/cgi/viewcontent.cgi?article=8499&context=etd |
| الاتاحة: | https://researchrepository.wvu.edu/etd/7396 https://researchrepository.wvu.edu/cgi/viewcontent.cgi?article=8499&context=etd |
| رقم الانضمام: | edsbas.CC0121A5 |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |