Fabrication And Capability Investigation On Thermoelectric Material Of Ca-Co-O System

With environment and energy problems becoming rigorous, thermoelectric materials, which convert heat into electricity and vice versa through the thermoelectric phenomena in solids , have recently attracted a renewed interest as a promising energy-conversion technology that is friendly to the environment. The thermoelectric phenomena, the history and the recent development progress of thermoelectric materials were reviewed in detailed at first. Showed: Ca₃Co₄O₉ is a layered compound consisting of the alternate stack layer which is responsible for the electric conduction and the insulated layer.We have selected calcium cobalt oxide(Ca₃Co₄O₉) and Ca3-xAxCo4O9-based as our research objects. In this thesis, we prepared the sample through the method of sol-gel, sintered the nano-meter powders by common pressure sintering at 900℃in 5 hour. And fabricated the Ca-Co-O-based thermoelectric materials by dopanting rare-earth compound and alkaline-earth.compound The microstructure and crystal composition of the samples were characterized by using XRD and SEM. We have surveyed the electrical conductivity by temperature, and we have accounted the thermal conductivity. The analysis showed that thermoelectric properties of dopanting sample have more increased. In this paper, the method of sol-gel course is analysed at detailed, and the matrix structure and thermoelectric properties are balanced by dopanting material.The result in my thesis are that it is an effective approach to min-granularity and max-activity nona-powders were fabricated by sol-gel method, and the probability of improvements exists if the appropriate fabrication technologies were fixed. It is viable to improve the thermoelectric properties of this system by introducing a good element and applying a appropriate dopanting proportion.