Abstract
In this study, Ca3−xAgxCo4O9 ceramics were synthesized by the sol–gel method combined with spontaneous combustion and cold isostatic pressing. The Ca3−xAgxCo4O9 ceramics were characterized via X-ray diffraction and scanning electron microscopy. Thermoelectric properties of the ceramics were measured from 323 to 673 K. The results indicated that Ag doping significantly affected the microstructure and thermoelectric properties. With the increase in Ag content and gradual increase in electrical conductivity, the Seebeck coefficient first increased and then decreased, whereas the thermal conductivity exhibited the opposite case. The figure of merit, ZT, was 0.17 at 673 K for the Ca2.8Ag0.2Co4O9 sample. These results indicated that the thermoelectric properties could be optimized remarkably with the substitution of Ag.
Highlights
Many industrial production processes or similar sources of significant waste heat have the characteristics of being dispersed and small scale
Thermoelectric materials are a type of new promising energy conversion materials, which provide a better solution for solving the problem of the direct discharge of waste heat [1]
Wu et al [12] explored the effects of Y and Fe co-doping on the high-temperature thermoelectric properties of the thermoelectric material Ca3 Co4 O9 prepared by the combustion method
Summary
Many industrial production processes or similar sources of significant waste heat have the characteristics of being dispersed and small scale. Thermoelectric conversion does not require traditional mechanical transmission parts and does not produce discarded objects during processing This type of promising energy conversion material does not generate noise and causes no pollution to the environment. Materials 2018, 11, 2573 performance of Ca3 Co4 O9 are more stable than those of Nax CoO2 at high temperatures because of its stable insulating layer structure, which makes Ca3 Co4 O9 more suitable for the direct conversion of high-temperature waste heat into electric energy. Higher thermoelectric properties can be obtained by optimizing the preparation process and element doping. Wu et al [12] explored the effects of Y and Fe co-doping on the high-temperature thermoelectric properties of the thermoelectric material Ca3 Co4 O9 prepared by the combustion method. Through Ag doping on the Ca site, the mechanism of its effect on the thermoelectric performance of Ca3 Co4 O9 was studied
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