【摘要】：熱電材料可將熱能與電能進(jìn)行直接轉(zhuǎn)換,未來在廢熱發(fā)電和熱電制冷有廣闊應(yīng)用前景。熱電材料目前的焦點(diǎn)是如何提高其熱電優(yōu)值ZT。本論文以BST和SnSe這兩種含化合物為研究對(duì)象,通過對(duì)材料摻雜及引入納米復(fù)合相等措施來探索提高其ZT值。論文的研究結(jié)果及創(chuàng)新點(diǎn)如下:(1)我們研究了 PbSe/BST復(fù)合體系的熱電性能。結(jié)果表明:當(dāng)在BST基體中引入PbSe納米粒子時(shí),PbSe納米顆粒附近會(huì)形成界面勢(shì)壘,因此抑制了少數(shù)載流子的輸運(yùn),實(shí)現(xiàn)了增強(qiáng)塞貝克系數(shù)和降低雙極效應(yīng)來降低熱導(dǎo)率,在此過程中我們提出了 "載流子散射工程"。因此,在復(fù)合了 0.2 vol.%的PbSe納米顆粒的BST樣品中,獲得最大ZT = 1.56(400K),在300K至500K的溫度范圍內(nèi)的平均ZTave達(dá)到1.44,相應(yīng)地,在冷端為300K和熱端為500K時(shí)實(shí)現(xiàn)了熱電轉(zhuǎn)換效率約10%。(2)我們研究了 Na摻雜對(duì)多晶SnSe熱電性能的影響。結(jié)果表明:Na摻雜SnSe的電導(dǎo)率提高了約兩個(gè)數(shù)量級(jí),這可歸因于Na原子替代了 Sn產(chǎn)生了大量的載流子(空穴);從而大幅提高了樣品的功率因子。通過在SnSe中摻Na,在873K時(shí)我們得到了最大的ZT=1.2,比純SnSe(ZT = 0.68)高出76%。(3)我們研究了 PbSe/Na_(0.003)Sn_(0.997)Se 和 PbTe/Na_(0.003)Sn_(0.997)Se 樣品熱電性能。樣品的熱導(dǎo)率大幅下降,這可歸因于引入了第二相引起了很強(qiáng)的聲子散射。在773K 時(shí),獲得了 ZT 值～1.3(f(PbSe)/Na_(0.003)Sn_(0.997)Se(f=0.5 vol.%)。
[Abstract]:Thermoelectric materials can convert heat energy and electric energy directly, and have broad application prospects in waste heat power generation and thermoelectric refrigeration in the future. The current focus of thermoelectric materials is how to improve their thermoelectric optimal value ZT. In this paper, BST and SnSe are taken as the research objects to explore how to improve the ZT value by doping the materials and introducing nanocomposite equality measures. The research results and innovations of this paper are as follows: (1) We studied the thermoelectric properties of PbSe/BST composite system. The results show that when PbSe nanoparticles are introduced into BST matrix, the interface barrier is formed near the PbSe nanoparticles, so the transport of minority carriers is suppressed, and the Seebeck coefficient is enhanced and the bipolar effect is reduced to reduce the thermal conductivity. In this process, we propose "carrier scattering engineering". Therefore, in the BST sample with 0.2 vol.% PbSe nanoparticles, the maximum ZT = 1.56 (400K) is obtained, and the average ZTave reaches 1.44 in the temperature range of 300K to 500K. The thermoelectric conversion efficiency is about 10% when the cold end is 300K and the hot end is 500K. (2) the effect of Na doping on the thermoelectric properties of polycrystalline SnSe is studied. The results show that the conductivity of Na doped SnSe is increased by about two orders of magnitude, which can be attributed to the large number of carriers (holes) produced by Na atoms instead of Sn, thus greatly increasing the power factor of the samples. By adding Na, to SnSe at 873k, we get the largest ZT=1.2,. The thermoelectric properties of PbSe/Na_ (0.003) Sn_ (0.997) Se and PbTe/Na_ (0.003) Sn_ (0.997) Se samples were studied. (3) the thermoelectric properties of PbSe/Na_ (0.003) Sn_ (0.997) Se and PbTe/Na_ (0.003) Sn_ (0.997) Se samples were studied. The thermal conductivity of the sample decreases greatly, which can be attributed to the strong phonon scattering caused by the introduction of the second phase. At 773k, the ZT value of ~ 1.3 (f (PbSe) / Na_ (0.003) Sn_ (0.997) Se (f 鈮，

本文編號(hào)：2473490