水热法制备硫化铋基材料及其热电性能表征

发布时间：2018-03-07 05:36

本文选题：热电材料　切入点：Bi2S3　出处：《湘潭大学》2015年硕士论文　论文类型：学位论文

【摘要】：热电材料是一种能实现热能和电能相互转换的功能材料,用其制成的热电器件,既能够利用工业生产中的废热进行发电,同时也能用作制冷设备。热电器件具有环境污染小、噪声污染低、重量轻、体积小、工作性能稳定等优点,因此热电材料的开发与应用受到科研工作者们的密切关注。Bi2S3作为一种低温热电材料,在室温下具有较低的热导率。采用储量丰富的S替代了最常用热电材料Bi2Te3中昂贵的稀有元素Te,大大降低了材料的成本,对于热电材料的研究具有重要意义。因此本论文以Bi2S3基热电材料的制备和性能表征为主,系统的研究了不同第二相复合对Bi2S3热电材料性能的影响。研究的主要内容包括以下几个方面:1.采用水热法制备了Bi2S3粉末,之后采用等离子烧结(SPS)技术制备了块体样品,系统地研究了水热合成温度、添加剂对样品形貌的影响,同时测试了样品的热电性能。实验结果表明:水热法合成的Bi2S3粉末都具有由条状纳米晶聚集而成的球状形貌,180°C下合成的粉末平均晶粒尺寸比150°C的小;当表面活性剂乙二醇的添加量为12 m L时,粉末的晶粒尺寸有明显的降低;随着十二烷基苯磺酸添加量的增加,粉末样品逐渐由球形向圆饼状形貌转变;样品的热电性能总体趋势与文献报道的相近,575 K时样品的ZT值为0.1。2.采用水热法结合SPS技术制备了BiCl3/Bi2S3复合块体,系统地研究了BiCl3复合量对样品热电性能的影响。实验结果表明SPS后样品的晶粒尺寸有所增加;适量的BiCl3复合Bi2S3既降低了样品的热导率,又提高了样品的电导率;样品的ZT值随着温度的升高而升高,当BiCl3复合量为0.25%时样品的ZT值最大,在724.3 K时达到了0.63,约为纯Bi2S3样品ZT值的3倍。3.采用水热法结合SPS技术制备了Ag2S/Bi2S3复合粉末及其块体样品,系统地研究了Ag2S复合量对样品形貌和热电性能的影响。实验结果表明随着Ag2S复合量的增加,样品中球形逐渐向圆饼状结构转变,但仍然保持分级结构的形貌特征;Ag2S/Bi2S3复合粉末样品的热导率都比纯Bi2S3样品的热导率低,当Ag2S复合量为3%时其ZT值最高,在724.3 K时达到了0.23。4.采用水热法结合SPS技术制备了Ag2S、BiCl3双复合Bi2S3样品,系统地研究了Ag2S、BiCl3复合量对Bi2S3样品热电性能的影响。实验结果表明双相复合样品的电导率有明显的提高,Bi2S3复合5%Ag2S和1%BiCl3样品具有最大的ZT值,在724.3 K时达到了0.59,比5%Ag2S复合样品的ZT值提高了近5倍。
[Abstract]:Thermoelectric material is a kind of functional material which can realize the conversion of heat energy and electric energy. The thermoelectric device made of thermoelectric device can not only generate electricity from waste heat in industrial production, but also be used as refrigeration equipment. Because of the advantages of low noise pollution, light weight, small volume and stable working performance, the development and application of thermoelectric materials have been paid close attention to by researchers. Bi2S3 is a kind of low-temperature thermoelectric material. It has low thermal conductivity at room temperature. The expensive rare element Tein in the most commonly used thermoelectric material Bi2Te3 is replaced by S with abundant reserves, which greatly reduces the cost of the material. Therefore, the preparation and characterization of thermoelectric materials based on Bi2S3 are the main topics in this thesis. The effects of different second phase compounding on the properties of Bi2S3 thermoelectric materials were systematically studied. The main contents of the study included the following aspects: 1.The Bi2S3 powder was prepared by hydrothermal method, and then bulk samples were prepared by plasma sintering. The effects of hydrothermal synthesis temperature and additives on the morphology of the samples were systematically studied. At the same time, the thermoelectric properties of the samples were tested. The experimental results showed that the average grain size of the Bi2S3 powders synthesized by hydrothermal method was smaller than that of 150 掳C with spherical morphology of 180 掳C, which was formed from the aggregation of nanocrystalline stripes. When the amount of surfactant ethylene glycol was 12 mL, the grain size of the powder decreased obviously, and with the increase of 12 alkyl benzenesulfonic acid, the morphology of powder gradually changed from spherical to round shape. The general trend of the thermoelectric properties of the samples is 0.1.2 when the samples are close to 575K reported in the literature. The BiCl3/Bi2S3 composite blocks were prepared by hydrothermal method combined with SPS technology. The effects of BiCl3 composition on the thermoelectric properties of the samples were systematically studied. The experimental results showed that the grain size of the samples increased after SPS, and the proper amount of BiCl3 composite Bi2S3 not only decreased the thermal conductivity of the samples, but also improved the conductivity of the samples. The ZT value of the sample increases with the increase of temperature. The ZT value of the sample reaches 0.63 at 724.3 K when the amount of BiCl3 compound is 0.25, which is about 3 times of the ZT value of pure Bi2S3 sample. The Ag2S/Bi2S3 composite powder and its bulk samples were prepared by hydrothermal method and SPS technique. The effects of Ag2S composition on the morphology and thermoelectric properties of the samples were systematically studied. The experimental results showed that the sphericity of the samples gradually changed to the round shape structure with the increase of the Ag2S composition. However, the thermal conductivity of Ag2S / Bi2S3 composite powder is lower than that of pure Bi2S3, and the ZT value is the highest when the Ag2S composition is 3. At 724.3 K, it reached 0.23.4.The Ag _ 2S _ 2O _ 3 BiCl _ 3 double composite Bi2S3 sample was prepared by hydrothermal method combined with SPS technique. The influence of the amount of Ag _ 2S _ 2 / BiCl _ 3 on the thermoelectric properties of Bi2S3 samples was systematically studied. The experimental results showed that the conductivity of the two-phase composite samples was significantly improved, and the maximum ZT values of the samples were obtained. At 724.3 K, the ZT value of the composite sample is 0.59, which is nearly 5 times higher than that of the 5Ag2S composite sample.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ135.32

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