本文關(guān)鍵詞：Bi-Te薄膜材料的電化學(xué)制備及其熱電性能研究　出處：《北京化工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 熱電材料 Bi_2Te_3 電沉積 薄膜 納米棒陣列

【摘要】：對于合金熱電薄膜材料,傳統(tǒng)的制備方法如氣相沉積、分子外延生長等存在著設(shè)備依賴性強(qiáng)、靶材價(jià)格昂貴和大面積制備困難等弊端。本論文采用電沉積的方法,通過調(diào)控電鍍液成分及電沉積工藝參數(shù),在金種層修飾的導(dǎo)電玻璃基底(Au/ITO)上,制備了較大面積的純相n型Bi2Te3和p型BixTey熱電薄膜材料,在具有良好的熱電性能的同時(shí)降低成本、簡化工藝。在10mM Bi3+15 mM HTeO2++1 M HNO3的電鍍液體系中,實(shí)現(xiàn)了對不同表面形貌的純相n型Bi2Te3熱電薄膜的可控制備：當(dāng)沉積電位為-0.20 V,沉積時(shí)間為120 s時(shí)制備的薄膜具有致密連續(xù)的麥粒狀微觀形貌,其電阻率為8.060×10-6Ω·m,載流子濃度為5.029×1020 cm-3,Seebeck系數(shù)為-64.949 μV·K-1,功率因子為5.234×104 W·m-1·K2,具有最佳的n型熱電性能。在12.5 mM Bi3+12.5 mM HTe02++1M HN03的電鍍液體系中,制備了具有Bi2Te3六方相結(jié)構(gòu)的p型富Bi熱電薄膜材料。在沉積電位為-0.25 V,沉積時(shí)間為60 s時(shí)制備的薄膜制具有致密連續(xù)的麥粒狀微觀形貌,其電阻率為4.525×10-6 Ω·m,載流子濃度為1.093×1021cm-3,Seebeck系數(shù)為57.168 μV.K-1,功率因子達(dá)了7.222×10-4W·m-1·K2,優(yōu)于n型純相Bi2Te3的熱電性能,實(shí)現(xiàn)了自身摻雜對載流予類型的改變和性能的優(yōu)化。對以上體系進(jìn)行分析,研究Bi-Te薄膜的共沉積機(jī)理：Bi3+優(yōu)先析出還原為Bi0,同時(shí)誘導(dǎo)HTeO2+發(fā)生欠電位沉積。在優(yōu)選電位下,致密薄膜的形核過程為依附于金種層的均勻形核；其穩(wěn)定生長階段發(fā)生Bi3+、HTeO2+的共沉積反應(yīng),且此時(shí)受擴(kuò)散步驟控制,晶核連續(xù)橫向長大,相互連接形成致密薄膜。在此沉積機(jī)理的啟發(fā)下,采用周期性脈沖雙電位法,對Bi-Te納米棒陣列的無模板輔助電沉積進(jìn)行了探索。陣列薄膜中Bi-Te納米棒的直徑約為80～120nm,長度約為250nm,分散均勻。其生長過程可描述為：當(dāng)體系加載短暫的還原電位時(shí),工作電極上制備了均勻的島狀Bi-Te晶核,再加載氧化剝離電位時(shí),溶解部分非晶態(tài)晶核中不穩(wěn)定的Bi原子；如此反復(fù)多次,最終得到Bi-Te納米棒陣列薄膜。
[Abstract]:For alloy thermoelectric thin film materials, the traditional preparation methods such as vapor deposition, molecular epitaxial growth have a strong equipment dependence. The price of target is expensive and the preparation of large area is difficult. In this paper, electrodeposition method is used to control the composition of electroplating solution and the parameters of electrodeposition process. A large area of pure n-type Bi2Te3 and p-type BixTey thermoelectric thin films were prepared on au / ITO substrate modified with gold seed layer. The electroplating bath system with 10mm Bi3 15mm HTeO2 1m HNO3 has good thermoelectric properties and lower cost and simplifies the process. The controllable preparation of n-type Bi2Te3 thermoelectric thin films with different surface morphologies was achieved: the deposition potential was -0.20 V. When the deposition time is 120 s, the films have dense and continuous wheat grain morphology, and their resistivity is 8.060 脳 10 ~ (-6) 惟 路m. The carrier concentration is 5.029 脳 10 ~ (20) cm ~ (-3) ~ (-1) Seebeck coefficient is -64.949 渭 V 路K ~ (-1). The power factor is 5.234 脳 104 W 路m-1 路K2. It has the best n type thermoelectric properties in the electroplating bath system of 12. 5 mm Bi3 12. 5 mm HTe02 1 M HN03. Bi-rich p-type thermoelectric thin films with Bi2Te3 hexagonal phase structure were prepared at a deposition potential of -0.25 V. The thin films prepared at the deposition time of 60 s have dense and continuous micromorphology of wheat grains, and their resistivity is 4.525 脳 10 ~ (-6) 惟 路m. The carrier concentration is 1.093 脳 1021cm-3. The Seebeck coefficient is 57.168 渭 V.K-1, and the power factor is 7.222 脳 10-4 W 路m-1 路K2. The thermoelectric properties of n-type pure phase Bi2Te3 are better than that of n-type pure phase Bi2Te3. The mechanism of co-deposition of Bi-Te thin films was studied. The precipitation and reduction of Bi-Te thin films were preferentially reduced to Bi0, and the underpotential deposition of HTeO2 was induced. The nucleation process of the dense film is uniform nucleation dependent on the gold seed layer. The codeposition reaction of Bi3 / HTeO2 occurs in the stable growth stage, which is controlled by the diffusion step, and the crystal nucleus grows laterally and connects with each other to form a compact film. The template-free assisted electrodeposition of Bi-Te nanorod arrays was investigated by means of periodic pulse double potential method. The diameter of Bi-Te nanorods in the array films was about 80 ~ 120nm. The growth process can be described as: when the system is loaded with a short reduction potential, a uniform island Bi-Te crystal nucleus is prepared on the working electrode. When the oxidation stripping potential is reloaded, the unstable Bi atoms in some amorphous nuclei are dissolved. Finally, Bi-Te nanorod array films were obtained after repeated times.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.2

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 劉宏,王繼揚(yáng);半導(dǎo)體熱電材料研究進(jìn)展[J];功能材料;2000年02期

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本文編號：1378460