硒化银的溶剂热法制备及热电性能研究

Solvothermal preparation of silver selenide and its thermoelectric properties

为了采用一种能耗低且耗时短的方法制备高性能的硒化银(Ag_(2)Se)基热电材料,选择以乙二胺为溶剂,硝酸银(AgNO_(3))和单质硒(Se)为原材料,采用溶剂热法合成不同银硒摩尔配比(n_(AgNO_(3))/n_(Se))的硒化银粉体后,再经过放电等离子体烧结(SPS)制备成块体。利用X射线衍射(XRD)与扫描电子显微镜(SEM)对样品进行物相分析及微观形貌观察,利用热电性能测试系统对样品的热电性能进行测试,通过模拟计算与热电发电器件的实际输出电压测试验证样品的性能。结果表明,随着n_(AgNO_(3))/n_(Se)的增大,硒化银粉体中第二相Ag单质的衍射峰增强,有利于优化样品的载流子输运特性。当n AgNO_(3)/n Se为2∶1时,所得样品具有最佳的室温热电性能,即在303 K时的热电优值(zT)约为0.74。当n_(AgNO_(3))/n_(Se)为1.9∶1时,所得样品在393 K时取得最大zT值,约为1.07,其在303~393 K之间的平均zT值约为0.82。模拟计算与热电发电器件的实际输出电压测试都表明,实验制备的硒化银块体具有替代N型Bi_(2)Te_(3)基热电材料的潜力。

To adopt a low energy consumption and short time-consuming method,high-performance silver selenide(Ag_(2)Se)based thermoelectric materials was prepared.The different silver-selenium molar ratios(n _(AgNO_(3))/n_(Se))silver selenide powder was synthesized by solvothermal method using ethylenediamine as the solvent,silver nitrate(AgNO_(3))and elemental selenium(Se)as raw materials.After spark plasma sintering(SPS)process,the block was obtained.X-ray diffraction(XRD)and scanning electron microscope(SEM)were used to conduct phase analysis and microscopic morphology observation of the sample.The thermoelectric performance test system was used to test the pyroelectric performance of the sample.The performance of the sample was verified by simulation calculation and actual output voltage test of thermoelectric power generation device.The results shows that with the increase of n_(AgNO_(3))/n_(Se),the diffraction peak of the second phase Ag element in the silver selenide powder increases,which is beneficial to optimize the carrier transport characteristics of the sample.The highest thermoelectric figure of merit(zT)about 0.74 at room temperature is obtained when the n_(AgNO_(3))/n_(Se) is 2∶1.A maximum zT of 1.07 is achieved at 393 K and its average zT value(zT avg)during 303 K~393 K is about 0.82 when the n_(AgNO_(3))/n_(Se) is 1.9∶1.Simulation calculation and actual output voltage test of thermoelectric power generation show that the experimentally prepared silver selenide bulk thermoelectric material is promising to replace N-type Bi_(2)Te_(3) based thermoelectric material.