【摘要】：CdO是一種N型半導體材料,具有抗氧化、高溫穩(wěn)定性好、原材料價格低廉等諸多優(yōu)點,在高溫熱電領域具有潛在應用前景。本論文首次研究了元素雙摻、納米復合、多孔結構對CdO多晶塊體材料電、熱輸運性能的影響規(guī)律和物理機制,以期通過電、熱輸運參量的調(diào)控來提高CdO的高溫熱電性能。論文主要內(nèi)容和結論如下:1.利用固相反應燒結技術制備了Mg/Ca雙摻的CdO多晶塊體并研究了摻雜濃度對樣品電、熱輸運性能的影響。實驗發(fā)現(xiàn),Mg/Ca雙摻在不顯著降低CdO功率因子的前提下可以大幅降低其熱導率,使熱電性能得以優(yōu)化。在最佳摻雜濃度下(3%Mg/Ca),樣品在1000 K時的熱電優(yōu)值為0.5,比未摻雜的樣品提高了約50%。2.利用固相反應燒結技術制備了納米Ag顆粒復合的CdO多晶塊體并研究了納米復合對樣品電、熱輸運性能的影響。一方面,納米Ag顆粒的摻入可以提升CdO的功率因子,這可能源于和能量有關的散射增強導致的載流子能量過濾效應;另一方面,納米Ag顆粒的摻入會引入大量的納米第二相、晶界和界面,使聲子的散射增強,熱導率降低。功率因子和熱導率的同時優(yōu)化使得CdO:Ag樣品具有較高的熱電優(yōu)值,1000 K時,CdO:3at%Ag樣品的ZT值達到了0.43。3.通過向CdO中摻入有機物PMMA制備了多孔結構的CdO多晶塊體并研究了PMMA摻入量對樣品電、熱輸運性能的影響。隨著PMMA的摻入,樣品的孔隙率增多而平均晶粒粒度減小,導致其熱導率大幅下降。盡管這些微米孔的引入也使CdO的功率因子受到影響,但最終因熱導率的大幅降低而使熱電優(yōu)值得以提升。1000 K時,5%PMMA摻入的CdO多晶塊體的ZT值達到了0.51。
[Abstract]:CDO is a kind of N-type semiconductor material, which has many advantages such as oxidation resistance, high temperature stability, low cost of raw materials and so on, so it has a potential application prospect in the field of high temperature thermoelectricity. In this paper, the effect of double doped elements, nanocomposites and porous structures on the electrical and thermal transport properties of CdO polycrystalline bulk materials is studied for the first time, and the physical mechanism is studied in order to improve the high temperature thermoelectric properties of CdO by regulating the electrical and thermal transport parameters. The main contents and conclusions are as follows: 1. The Mg- / Ca doped CdO polycrystalline bulk was prepared by solid state reaction sintering and the effect of doping concentration on the electrical and thermal transport properties of the samples was investigated. It is found that the thermal conductivity can be greatly reduced and the thermoelectric properties can be optimized by adding mg / Ca without significantly reducing the power factor of CdO. At the optimum doping concentration (3mg / Ca), the thermoelectric excellent value of the sample at 1000 K is 0.5, which is about 50. 2% higher than that of the undoped sample. Nanocrystalline Ag composite CdO polycrystalline bulk was prepared by solid state reaction sintering and the effect of nano-composite on the electrical and thermal transport properties of the samples was studied. On the one hand, the incorporation of nano-Ag particles can enhance the power factor of CdO, which may be due to the carrier energy filtering effect caused by the enhanced scattering related to energy; on the other hand, the incorporation of nano-Ag particles will introduce a large number of nanometer-second phases. Grain boundary and interface increase phonon scattering and decrease thermal conductivity. When the power factor and thermal conductivity are optimized simultaneously, the ZT value of CdO _ (10) O _ (3) AT Ag sample reaches 0.43.3 at 1000K. Porous CdO polycrystalline bulk was prepared by incorporation of organic compounds PMMA into CdO and the effect of PMMA incorporation on the electrical and thermal transport properties of the samples was investigated. With the incorporation of PMMA, the porosity of the sample increases and the average grain size decreases, which results in a significant decrease in the thermal conductivity of the sample. Although the introduction of these micron pores also affected the power factor of CdO, the ZT value of CdO polycrystalline bulk doped with 5 PMMA reached 0.51when the thermoelectric excellent value was raised by the decrease of thermal conductivity.
【學位授予單位】：河北大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN304.21

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本文編號：2122961