Projects / Programmes
New materials for power conversion: Oxide semiconductor thermoelectrics
| Code |
Science |
Field |
Subfield |
| 2.04.01 |
Engineering sciences and technologies |
Materials science and technology |
Inorganic nonmetallic materials |
| Code |
Science |
Field |
| T150 |
Technological sciences |
Material technology |
| Code |
Science |
Field |
| 2.05 |
Engineering and Technology |
Materials engineering |
Energy conversion, thermoelectrics, oxide semiconductors, perovskites, thermal conducivity, phonon glass
Researchers (22)
Organisations (3)
Abstract
In the scope of the project we intend to study oxide thermoelectric materials, which could in the future present a sustainable solution for harvesting electricity from daily-generated excess heat. The most effective thermoelectric materials that have to date been developed are based on alloys such as tellurides, which contain toxic elements and are furthermore prone to decomposition at elevated temperatures under atmospheric conditions. In the last decade, however, it has been shown that some semiconductive oxides exhibit promising thermoelectric properties. Using oxide materials instead of alloys would improve the stability of materials in thermoelectric converters and thus enable harvesting “waste heat” at higher temperatures. The research field of oxide thermoelectrics is relatively young and therefore represents a scientific and technological opportunity.
The research within the project would be divided into three parts, which would include optimization of processing of known thermoelectric oxides, investigation of new oxide thermoelectrics and building of prototype thermoelectric modules containing oxide materials:
-In the first part we would study the correlation of crystal chemistry and processing parameters to the microstructure and resulting thermoelectric properties, which has up to know been poorly described in the literature. We would mainly focus on cobaltates such as NaxCo2O4 and doped ZnO, which are the best known p- and n-type oxide themoelectrics.
-The second part of the project would be dedicated to development of new oxide themoelectrics with the emphasis on studies of physical background of the measured properties via thermopower Seebeck coefficient, electrical conductivity, thermal conductivity and heat diffusion measurements in order to design materials with properties close to phonon glass-electron crystal.
-Within the scope of the third part we intend to build prototype thermoelectric modules containing newly developed thermoelectric oxides. We would mainly focus on minimizing the contact resistance between thermoelements and electrodes by applying the nanotechnological approach of in-situ synthesis of conductor material.
Significance for science
The research performed during the last two decades indicates that materials with layered crystal structure exhibit combination of electrical and thermal transport properties most favorable for development of new thermoelectric materials. Some types of layered structures confine electrons, which results in an increase of thermopower and electrical conductivity. Simultaneously layered structures effectively scatter phonons, which leads to a decrease of thermal conductivity. To make use of these characteristics of layered structures polycrystalline materials need to be textured for which methods like hot pressing and sintering with electrical pulses are most frequently employed. The project team has shown that coherently intergown structures can be readily sintered to a high degree of texturing using conventional sintering methods, which is economically important for further development of the field. Furthermore the project team discovered, utilizing atomically resolved microscopy and theoretical calculations, so far unknown structural anomalies between the layers of layered cobaltates. These findings point to new possibilities of lowering the thermal conductivity of materials and thus new approaches to the design of thermoelectric materials.
Significance for the country
The research of thermoelectric materials falls in the scope of efforts to find sustainable and ecologically acceptable solution to the emerging energy problem. Increasing number of publications and involvement of numerous research groups indicate that thermoelectrics are a fast growing scientific field. With the research of thermoelectric materials the project team started a new research direction in Slovenia, which will contribute to scientific establishing and recognizability of the country. Furthermore development of new thermoelectric materials represents possibility of increasing efficiency of new and existing systems for energy conversion using locally generated knowledge.
Most important scientific results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2012,
2013,
final report,
complete report on dLib.si
