Microstructure and thermoelectric properties of Bi1.9Lu0.1Te3 compound

Effect of fabrication conditions on microstructure and thermoelectric properties of the Bi1.9Lu0.lTe3 compound was studied. Starting nanopowder with mean nanoparticle size of -37 nm was synthesized by a microwave-solvothermal method. In order to prepare samples with various micro-grained structures, the synthesized nanopowder was compacted by two methods. The first method is cold isostatic pressing with further high- temperature annealing, while the second method is spark plasma sintering at various temperatures of process （653 and 683 K）. It is found that mean grain size is equal to -290,-730 and -1160 nm for cold isostatically pressed and spark plasma sintered at 653 and 683 K samples, respectively. The micro-grained sample with maximum mean grain size shows the best thermoelectric properties. This sample is structurally inhomogeneous and has the lowest thermal conductivity and the specific electrical resistivity. Maximum dimensionless figure of merit for this sample is equal to -0.9 for temperature range of 450-500 K.

N型(Bi2Te3)0.9(AgxBi2-xSe3)0.1热电材料的快速热压法制备及性能表征

采用水热法制备平均粒度约300 nm的六方相Bi2Te3纳米粉末。再以Bi2Te3粉末为原料,采用封管熔炼法制备N型(Bi2Te3)0.9(AgxBi2-xSe3)0.1(x为Ag的摩尔分数。x=0.1,0.2,0.3,0.4)合金粉体材料,通过快速热压制备N型(Bi2Te3)0.9(AgxBi2-xSe3)0.1块状热电材料。在300～550 K温度范围内研究该材料的热电性能与Ag掺杂量之间的关系,以及热压工艺对材料热电性能的影响。结果表明在775 K,40 MPa条件下烧结20 min后材料的相对密度达到97%以上,晶粒大小在3μm左右。当Ag掺杂量x=0.2时,在300 K温度下热导率达到最小值0.71 W/mK,同时获得最高的热电优值(ZT值)1.07。

Bi6Fe1.9Co0.1Ti3O18纳米片负载Au尺寸对其可见光光催化性能的影响

我们通过一种简单的化学方法制备了具有可见光催化性能的Bi6Fe1.9Co0.1Ti3O18/Au(BFCTO/Au)纳米复合材料。结果表明,通过负载不同颗粒大小的Au纳米颗粒(~23 nm、~36 nm、~55 nm和~80 nm),BFCTO的可见光光催化性能明显增强,其中负载粒径为~23 nm的Au纳米颗粒的BFCTO/Au-1样品的可见光光催化效率最高。

添加Sb的Ga_2Te_3合金热电性能

本研究采用等摩尔分数的Sb元素替换Ga2Te3中的Ga元素,并利用放电等离子烧结技术制备Ga1.9Sb0.1Te3合金,研究其微观结构和热电性能。结果表明,添加Sb元素后,材料的Seebeck系数为130～240μV/K,明显低于单晶Ga2Te3,电导率为3600～1740??1·m?1,至少是单晶Ga2Te3的17倍,热导率提高近25%。在649K时Ga1.9Sb0.1Te3合金的热电优值(ZT)达到最大值0.1,是同温度下单晶Ga2Te3ZT值的3倍。

共晶二元Sn基焊料与Bi_2(Te_(0.9)Se_(0.1))_3基热电材料的界面反应

热电元件焊接常用的焊料为铟基焊料和铋基焊料。由于碲化铋材料与低熔点合金焊料之间的浸润性较差,常在碲化铋基热电元件上镀覆镍镀层。本文在大气条件下,不加助焊剂,采用共晶SnBi和SnIn焊料分别对n型热电元件进行了铺展实验及界面显微组织的观察。铺展温度主要选择了210℃和300℃,实验表明300℃界面结合比250℃更好。此外,热电元件表面通过蒸镀仪蒸镀上薄镍层。对含薄镍层的热电元件与不含镍层的热电元件的铺展实验进行对比,得到薄镍镀层可能会增加界面裂纹。