【摘要】：熱電材料是可以將熱能轉(zhuǎn)化成電能的材料,在溫差發(fā)熱和制冷上被廣泛應(yīng)用。理論研究和實(shí)驗(yàn)探究均表明降低材料維度可以有效提高材料熱電轉(zhuǎn)化效率。碲化鉍基化合物是目前室溫下性能最好的熱電材料。本文采用高真空熱蒸發(fā)鍍膜法,以高純碲化鉍粉末為蒸發(fā)源,在襯底380℃蒸發(fā)源360℃鍍膜反應(yīng)5min即可制備出尺寸較大且均勻的碲化鉍拓?fù)浣^緣體納米薄膜。用掃描電子顯微鏡(SEM)、X射線衍射儀(XRD)、高分辨率透射電子顯微鏡(HRTEM)等手段對(duì)鍍膜生長(zhǎng)10min的樣品產(chǎn)物的形貌和結(jié)構(gòu)進(jìn)行表征,樣品表面呈現(xiàn)出螺旋形貌的臺(tái)階生長(zhǎng)三角結(jié)構(gòu)納米薄膜,臺(tái)階邊緣生長(zhǎng)出直立排列的片狀結(jié)構(gòu),對(duì)其螺旋形貌生長(zhǎng)機(jī)制進(jìn)行了分析。使用原子力顯微鏡(AFM)對(duì)螺旋結(jié)構(gòu)和直立排列的片狀結(jié)構(gòu)高度厚度進(jìn)行統(tǒng)計(jì)測(cè)試。結(jié)果表明,鍍膜生長(zhǎng)10min的樣品螺旋生長(zhǎng)的臺(tái)階結(jié)構(gòu)厚度大致為15-20nm,直立排列的片狀結(jié)構(gòu)厚度在40-80nm左右、高度大概在150-200nm左右。采用一步水熱法,以Bi(NO_3)_3·5H_2O為Bi源,Na_2TeO_3為Te源,葡聚糖(分子量40000)為還原劑和碳包裹層,制備了不同Bi和Te摩爾比的碲化鉍樣品。利用SEM、XRD、HRTEM對(duì)不同摩爾比樣品的物相和形貌進(jìn)行了表征。結(jié)果表明,Bi的摩爾百分比會(huì)影響產(chǎn)物最終的形貌。隨著Bi的摩爾百分比的升高,樣品形貌趨向于生長(zhǎng)為二維結(jié)構(gòu)。對(duì)Bi:Te=1:3碳加入量不同的樣品進(jìn)行光催化測(cè)試,碳含量為0.03mmol時(shí)降解率達(dá)到87.5%。對(duì)碳含量為0.02mmol而Bi和Te摩爾比不同的樣品進(jìn)行光催化測(cè)試,Bi:Te=1:2降解率最高,達(dá)到70.8%。對(duì)納米線的生長(zhǎng)機(jī)制進(jìn)行了闡述。
[Abstract]:Thermoelectric materials, which can convert heat energy into electric energy, are widely used in temperature difference heating and refrigeration. Both theoretical and experimental studies show that reducing the material dimension can effectively improve the efficiency of thermoelectric conversion. Bismuth telluride compounds are the best thermoelectric materials at room temperature. In this paper, large and uniform bismuth telluride topological insulator nanocrystalline films were prepared by high vacuum thermal evaporation method and high purity bismuth telluride powder as evaporation source. Scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) were used to characterize the morphology and structure of 10min films. The growth mechanism of the spiral morphology of the flat structure with vertical arrangement on the edge of the step was analyzed. Atomic force microscopy (AFM) was used to measure the height and thickness of helical and vertical lamellar structures. The results show that the thickness of spiral growth of 10min is about 15-20 nm, the thickness of vertically arranged sheet structure is about 40-80nm and the height is about 150-200nm. Bismuth telluride samples with different Bi and Te molar ratios were prepared by one-step hydrothermal method with Bi (no _ 3) _ 3H _ 2O as Bi source and Na _ 2TeO _ 3 as Te source, dextran (molecular weight 40000) as reducer and carbon encapsulation layer. The phase and morphology of the samples with different molar ratios were characterized by means of SEM-XRD- HRTEM. The results show that the mole percentage of Bi will affect the final morphology of the product. With the increase of the molar percentage of Bi, the morphology of the sample tends to grow into two dimensional structure. The photocatalytic test was carried out on the samples with different carbon content of 1: 3: 1: 3, and the degradation rate reached 87.5% when the carbon content was 0.03mmol. The photocatalytic test was carried out on the samples with carbon content of 0.02mmol and different molar ratio of Bi and Te. The degradation rate of Bi: Te1: 2 was the highest, reaching 70.8%. The growth mechanism of nanowires was described.
【學(xué)位授予單位】：新疆大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O484

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