Ce掺杂Bi_2O_3纳米棒及热电性能研究

Ce-doped Bi_2O_3 nanorods and thermoelectric properties

当今,大量化石能源(煤炭、石油和天然气)燃烧造成的环境污染和能源短缺的问题日益严重.寻找一种高效、绿色、低成本和可持续的能源材料是现今能源科学研究的重点工作之一.热电技术是能够利用收集工厂、汽车等产生的废热形成温度梯度通过塞贝克效应转化为电能,通过珀尔帖效应可用于制冷.热电材料是热电技术的关键.因此,热电材料的性能研究对于未来解决能源问题具有举足轻重的作用. Bi_2O_3是一种绿色环保、低成本同时具有较高的塞贝克系数的热电材料.但由于导电性差,到目前为止, Bi_2O_3的功率因子(PF)最大为1.05×10^(-3)WK^(-2)m^(-1).制备纳米材料是提高热电转换效率的重要方法之一,本文通过简单的化学气相沉积法(CVD),成功合成Ce_xBi_(2-x)O_3(x=0, 0.1%, 0.2%, 0.3%)纳米棒,并对其进行化学成分、形貌和微观结构分析.常规X-射线衍射花样(XRD)/小角掠射XRD (GIXRD), X-射线光电子能谱(XPS)测量,证明所得的样品为Ce_xBi_(2-x)O_3.通过扫描/透射电子显微镜观察,发现产物为分散均匀的纳米棒,并冷压成圆块.本文用热电性能测试系统(ZEM-3)对样品的电输运性能(赛贝克系数和电阻率)进行测试,并利用激光热导仪(LASER FLASH DLF-1)和差式扫描量热仪(EXSTAR 6200)测试样品的热导率.结果表明,在479 K下, Ce_(0.2)Bi_(1.8)O_3样品的功率因子(PF)为1.265×10-2WK^(-2)m^(-1),ZT值为0.57×10^(-2),远高于未掺杂的样品,因此Ce掺杂的Bi_2O_3热电材料在能源/材料/器件具有良好的应用前景.

Nowadays, the problem of environmental pollution and energy shortage caused by the burning of a large number of fossil fuels （coal, oil and gas） is becoming more and more serious. Finding an efficient, green, low-cost and sustainable energy material is the focus of energy science research now. Thermoelectric technology is able to generate a temperature gradient by collecting waste heat from factories, cars and so on and converts it into electricity through the Seebeck effect, and through the Peltier effect, it can be used for refrigeration. Thermoelectric material is the key to the thermoelectric technology. Therefore, the performance research of thermoelectric materials will play an important role in solving energy problems in the future. As a green environmental material, BiEO3 possesses a low cost and high Seebeck coefficient of thermoelectric materials. Due to poor electrical conductivity; however, the power factor （PF） of BizO3 has so far been less than 1.05×10^-3 W K^-2 m. It is one of the most important way to improve the efficiency of thermoelectric conversion to obtain counterpart nanomaterials. In this paper, through a simple chemical vapor deposition （CVD）, CexBi2-xO3 （x=0%, 0.1%, 0.2%, 0.3%） nanorods were successfully fabricated. As for the chemical composition, morphology, and microstructure analysis, conventional X-ray diffraction （XRD） pattern/small grazing incident X-ray diffraction （GIXRD）, X-ray photoelectron spectroscopy （XPS） were used to prove to be the CexBi2-xO3 sample. Through scanning/transmission electron microscope, it was found that products were dispersed uniformly nanorods, and counterpart samples cold be pressed into a round piece. Based on Seebeck coefficient/electrical resistivity measurement system using thermoelectric performance testing system （ZEM-3）, electrical transport properties of the samples were characterized. Laser thermal conductivity meter （LASER FLASH DLF-1） and EXSTAR differential scanning calorimeter （6200） were used to test the thermal conductivity of the sample. The obtained results showed that the power factor （PF） and ZT value of the sample （Ce02Bi1.803） arrived at 1.265×10^-2 W K^-2m^-1 and 0.57×10^-2 at 479 K, respectively, which is far higher than that of the un-doped samples. So Ce-doped Bi2O3 thermoelectric nanomaterials have a good application prospect for energy, material and devices.