The Research And Preparation On SnO₂-based Thermoelectric Ceramic Materials

In this thesis,preparation techniques and thermoelectric properties about semiconducting BaSnO₃ ceramics are researched. The samples are prepared by using BaCO₃ and SnO₂ as starting materials,a few of puities as additives,donors and acceptors ,and conventional solid-state reaction method. The materials prepared have high density over 90% theoretical value,good grains with size of 1-5μm and average diameter 4μm,clear grain boundary structure and without other phase between grain and grain boundary.The effect of Na₂CO₃ and Y₂O₃ doping as acceptors to BaSnO₃ is study detailedly. Result indicate thet Na₂CO₃ dopping solely to improve the thermoelectric properties ineffectively, Y₂O dopping have some effect in improving the themoelectric properties of BaSnO₃ ceramics.While effectively doping with MnO₂ and better with more quantities,but effect the conduction badly when dope MnO₂ too much. Using an appropriate quantity and ratio can get a better result, i.e. apparent Thermoelectric power factor 0.46μwm^-1K^-2 and Resistivity 0.053Ω·m.Sb₂O₃ doped have powerful performance as additive to BaSnO₃ ceramics sintering, can improve the material density, and reduce the temperature for sintering,make material becoming ceramics at 1350℃with large quantity. The sintering temperature is a key factor to performance of BaSnO₃ ceramics. With the temperature reducing,the worse sintering effect will lead to the bad thermoelectric properties. Using an appropriate quantity can get b better result, i.e.apparent Thermoelectric power factor 0.44μwm^-1K^-2. samples with purity granin phase can be attained with 1350℃temperature.