Low temperature electrical and thermal transport properties of the Ca3−xSbxCo4O9 system
Low temperature electrical and thermal transport properties of the Ca3−xSbxCo4O9 system
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DOI：
10.1007/s10854-012-0792-8
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发表时间：
2012-06
期刊：
影响因子：
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通讯作者：
S. Demirel;M. Aksan;S. Altın
中科院分区：
文献类型：
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作者：
S. Demirel;M. Aksan;S. Altın
本研究采用固相反应技术制备了Ca3−xSbxCo4O9（x = 0.0, 0.5, 0.75和1.0）体系。XRD分析发现，随着体系中Sb浓度的增加，杂质相的形成导致主晶格的畸变。SEM-EDX结果表明，在ca3co4o9体系中，随着Sb的增加，晶粒尺寸减小。电阻率ρ值随sb含量的增加而增大，绝缘性能随温度的降低而降低。制备的样品具有正热电功率S值，表明空穴是样品中主要的载流子。Svalue随温度的降低而减小。费米能EF和载流子浓度n因sb取代而降低。sb取代导致体系导热系数κ降低，这是由于体系中声子导热系数κph降低所致。由于ρ的大幅增加，优点值ZT值显著下降。杂质、缺陷和Sb取代引起的畸变是导致电学和热输运性质发生较大变化的原因。
In this study, the Ca3−xSbxCo4O9(x = 0.0, 0.5, 0.75 and 1.0) system was fabricated using solid-state reaction technique. From the XRD analysis, it was found that increase of the Sb concentration in the system caused formation of impurity phases and therefore a distortion in the main lattice. The SEM-EDX results showed that the grain size reduced with increasing Sb in the Ca3Co4O9system. The resistivity,ρ, value increased with increasing the Sb-content and insulating behavior was obtained as the temperature was decreased. The samples fabricated have positive thermoelectric power,S, value, suggesting that holes are dominant charge carriers in the samples.Svalue decreased with decreasing the temperature. The Fermi energy,EF, and the carrier concentration,n, decreased by the Sb-substitution. The Sb-substitution caused a decrease of thermal conductivity,κwhich is due to reduction of the phonon thermal conductivity,κph,in the system. Figure of merit,ZT, value decreased significantly due to strongly increase inρ. The impurities, defects and distortion with substitution of Sb are responsible for large variation on electrical and thermal transport properties.