Thermoelectrics (TE) are a promising energy conversion technology for power generation and cooling systems. The utilization of this heat is one of the aims of developments in the field of thermoelectricity. The thermal and electrical properties of the materials as the heart of thermoelectric devices dictate conversion efficiency and technological viability. Studying the fundamental properties of potentially new thermoelectric materials is of great importance for improving device performance and understanding the electronic structure of materials systems The ef?ciency of the TE material performance is quanti?ed by a dimensionless ?gure of merit ZT=S2 ?T/?, where S is the Seebeck coef?cient, ? is the electrical conductivity, ? is the thermal conductivity, and T is the absolute temperature. Accordingly, a good TE material with high ZT value requires the combination of high electrical conductivity, low thermal conductivity, and high thermopower or Seebeck coef?cient S. Materials that meet these requirements are found for typically heavily doped, small band-gap semiconductors or semimetals. However, the temperature ranges over which the existing materials could be used together with their stability, cost and toxicity led to the investigation of oxide materials. High temperature stability of ides in air allows using at temperatures found in combustion engine exhaust systems and power stations. The availability, relatively low cost and reduced toxicology concerns of oxides have been fundamental drivers for research in this large group of materials. Many di?erent classes of oxide materials have been investigated including SrTiO3, CaMnO3, Ca3Co4O9, In2O3 and NiO. These systems have been well reviewed in recent years. The values of ZT are approaching , which makes commercial viability more likely. However, the complex nature of the materials with variable densities, grain sizes, crystal structures, stoichiometries and oxygen contents means that it is often di?cult to compare their properties. The continuing desire for both increased energy e?ciency coupled with the need for ever more sensors will continue to provide the incentive for further work in this field. Obtaining and researching nano sized samples of these materials will improve the quality of materials and increase the value.
The main goal of the project is the development of methods for obtaining high-quality ceramics from nano dimensional compounds with a pyrovskite structure, their doping to increase the ZT, studying their chemical and physical properties, toxicity as well as applications as high-temperature thermoelectric materials for energy generation from waste heat sources.To meet this goal, the following tasks will be undertaken:
1. Oxides of La, Nd, Gd, Tb, oxides as well as of Ti, Co, Mn, Sr, Ca and their solid solutions of nano-size will be synthesized as nano-sized powders by mechanical alloying, sol-gel procedure, and other new chemical methods will be used for this aim.
2. New nano-size compounds perovskite structure, their solid solutions will be obtained as promising TE materials.
3. Phase, chemical compositions and dispersion of new TE materials will be determined.
4. Structural, physical and chemical properties of the prepared materials will be studied to characterize them as high temperature thermoelectric (TE) materials.
5. Toxicological-hygienic assessments of all newly synthesized nano-materials will be studied to assess their possible use as TE materials.
Status in the sphere of investigations in the Institute of Chemistry AS RT:
? A review has been prepared of the area and equipment has been developed for synthesis of ultra disperse (nano) powders of REE oxides, oxides of Ti, Co, Mn, by sol-gel method and by the chemical methods.
? A review has been prepared of environmental problems of nano-technologies and nano-materials in field and the corresponding equipment needs for such work.
Effect of suggested project on the progress in this sphere.? As we know, issue of thermal energy transformation into electrical, its transmission to the long distances is one of the most important goals of science and engineering. As a result of synthesis of new nano materials that promote to solve this issue, makes its contributions to the progress of this sphere. This type of transformation of thermal energy into electrical is ecologically clean method.
? In this connection, the synthesis and development of new TE nano-materials on the basis pyrovskite oxides will have both scientific and practical value.
?The study of toxicological properties of nano-size powders of different phase and chemical composition
and with given dispersion will open possibilities of evolution of the technological processes for these new materials in terms of toxically effect minimization relative to human, animals and environment
Expected results and their application. In the result of the works new materials with high ZT will be obtained to transform thermal energy into electrical and to transmit them to long distances, energy generation from waste heat sources, as energy efficiency materials. As a result of the works within the Project novel composite TE nanomaterials based on oxides nanostructures will be obtained, and their physico-chemical properties will be carefully studied. These composites are expected to find their use for the creation of new high temperature TE materials, catalysts. The applicability of such composites in these fields will be investigated and their toxicity will also be assessed.
