| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
In order to obtain higher efficient ceramic thermoelectric converting materials, semiconductor ceramics with dispersing nano-metal particles, such as CuO-added AgSbO_3, were studied. First of all, to clarify the reason of high efficiency of the material, relation between the size and the distribution of Ag particles and the thermoelectric properties were investigated. (a) Calcinating conditions and (b) preparation process of raw powders were specifically considered. The thermoelectric properties of ZnO, CoO, Fe_2O_3. PdO or WO_3-added AgSbO_3 were also investigated. Furthermore, as another example system of metal nano particles and semiconductors, Ag-added Ca_3Co_4O_3 was also studied. The main results of this study is as follows.
(1) From the consideration of the condition during synthesis and calcinations, thermoelectric properties of AgSbO_3 system is affected by the size and distribution of dispersing silver particles.
(2) It was found that addition of ZnO, CoO, Fe_O3 and PdO made electrical conductivity of AgSbO_3 increase and Seebeck coefficients decrease, which meant the carrier concentration was increased. Density of sintered bodies of AgSbO_3 increase by addition of WO_3, and carrier concentration also increase.
(3) Deposition of LaNiO_3-like phase is detected by Fe_2O_3 addition in the La_2NiO_4 ceramics. However, the carrier concentration was decreased and higher efficiency of thermoelectric property was not obtained.
(4) Calculation of density of state of AgSbO_3 made to be clear that the conduction orbital is 5s of antimony and the modification of this orbital is the key of high thermoelectricity.
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