【摘要】：Ag In Se2作為一種典型的I III VI2黃銅礦結(jié)構(gòu)化合物,其中存在固有的陰陽離子缺陷對(2V-1Ag+In2+Ag)。選擇Zn原子替代其中Ag原子,Zn原子會占位在Ag或者In的晶格位置,從而產(chǎn)生多種反結(jié)構(gòu)缺陷,例Zn Ag1+和Zn In1-缺陷,分別成為施主和受主。這些缺陷對材料的能帶結(jié)構(gòu)和輸運性能會產(chǎn)生很大的影響,從而調(diào)控熱電性能。α?In2Se3是一種層狀結(jié)構(gòu)半導體化合物,其中存在1/3 In原子層空位并有少量未成鍵的Se原子,這同樣對優(yōu)化結(jié)構(gòu)和熱電性能具有巨大的潛力。本文研究了Ag1-x In Znx Se2(x=0.025,0.05,0.1),In2-x Znx Se3(x=0.005,0.01,0.02)兩種材料,具體研究成果總結(jié)如下:1、根據(jù)化學計量比設計制備Ag1-x In Znx Se2(x=0.025,0.05,0.1),采用X射線粉末衍射結(jié)合GSAS結(jié)構(gòu)精修原子占位情況。通過精修,發(fā)現(xiàn)Zn原子占據(jù)在In原子和Ag原子的位置幾率基本相同。在815 K,且x=0.01時,材料Ag1-x In Znx Se2(x=0.1)的ZT值為1.05±0.12,遠遠高于本征Ag In Se2。2、采取同樣的方法制備In2-x Znx Se3(x=0.005,0.01,0.015,0.02)化合物,并對其進行晶體結(jié)構(gòu)和熱電性能研究。實驗發(fā)現(xiàn)Zn有插層到In2Se3中Se-Se層(van der waals)間隙的跡象,但尚需進一步證實。這一插層降低了載流子跨越層隙的阻力,極大地提高了電導率。同時,插層還使晶格結(jié)構(gòu)發(fā)生嚴重畸變,降低了晶格熱導率。通過熱電性能測試分析,在垂直于壓制方向,當x=0.01、溫度為917K時,熱電優(yōu)值ZT取得最大值0.75,為本征α-In2Se3的3.27倍;而平行于壓制方向,熱電優(yōu)值ZT取得最大值1.22,約為本征α-In2Se3的5.0倍。因而,研究得出,Zn的摻入大大改善了α-In2Se3的熱電性能。
[Abstract]:Ag In Se2 is a typical structural compound of III VI2 chalcopyrite, in which there are inherent anion defect pairs (2V-1Ag In2 Ag). The Ag atom is replaced by the Zn atom, and the Zn atom will occupy the lattice position of the Ag or In, resulting in a variety of anti-structural defects. For example, the Zn Ag1 and Zn In1- defects become the donor and the acceptor, respectively. These defects have a great influence on the energy band structure and transport properties of the materials, thus regulating the thermoelectric properties. A? In2Se3 is a layered semiconductor compound with a third of the In atom layer vacancy and a small amount of unbonded Se atoms. It also has great potential for optimizing structure and thermoelectric performance. In this paper, two kinds of materials, Ag1-x In Znx Se2 and In2-x Znx Se3, have been studied. The results are summarized as follows: 1. According to the stoichiometric design, Ag1-x In Znx Se2 was prepared by means of X-ray powder diffraction and GSAS structure refinement. By refinement, it is found that the probability of Zn atoms occupying the positions of In atoms and Ag atoms is almost the same. At 815K, the ZT value of the material Ag1-x In Znx Se2 (xC0. 1) is 1. 05 鹵0. 12, which is much higher than that of the intrinsic Ag In Se2.2, which uses the same method to prepare the In2-x Znx Se3 compound (xK0. 005, 0. 01, 0. 015 ~ 0. 02). The crystal structure and thermoelectric properties were studied. It is found that Zn intercalates the (van der waals) gap of Se-Se layer in In2Se3, but it needs further confirmation. This intercalation reduces the resistance of carriers to cross the layer gap and greatly increases the conductivity. At the same time, the intercalation also leads to the serious distortion of the lattice structure and reduces the lattice thermal conductivity. Through the thermoelectric performance test and analysis, when the temperature is 917K, the maximum value of ZT is 0.75, which is 3.27 times that of the intrinsic 偽-In2Se3, perpendicular to the pressing direction, when XG is 0.01 and the temperature is 917K. Parallel to the pressing direction, the maximum value of thermoelectric ZT is 1.22, which is about 5.0 times of the intrinsic 偽-In2Se3. Therefore, the study shows that the incorporation of Zn greatly improves the thermoelectric properties of 偽-In2Se3.
【學位授予單位】：中國礦業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN304

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相關期刊論文 前1條

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本文編號：2427472