Tie Jian, Xu Guiying, Li Yawei, Fan Xian, Yang Quanxin, Nan Bohang
Beijing Municipal Key Lab of Advanced Energy Materials and Technology, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810016, China.
Materials (Basel). 2023 Jul 24;16(14):5204. doi: 10.3390/ma16145204.
CuSe is a promising thermoelectric (TE) material due to its low cost, Earth abundance, and high thermoelectric properties. However, the biggest problem of CuSe is its unstable chemical properties. In particular, under the action of an electric field or gradient temperature field, the chemical potential of copper ions inside the material increases. When the external field is strong enough, the chemical potential of copper ions at the negative end of the material reaches the chemical potential of elemental copper. Under these conditions, copper ions must precipitate out, causing CuSe to be unstable, and making it unsuitable for use in applications. In this study, we prepared CuMnSe (x = 0, 0.02, 0.04 and 0.06) series bulk materials by vacuum melting-annealing and sintered by spark plasma sintering (SPS). We investigated the effects of Mn doping on the composition, microstructure, band structure, scattering mechanism, thermoelectric properties, and stability of CuSe. The results show that Mn doping can adjust the carrier concentration, promote the stabilization of the β-phase structure and improve the electrical properties of CuSe. When x = 0.06, the highest power factor () value of CuMnSe at 873 K was 1.62 mW m K. The results of carrier scattering mechanism analysis based on the conductivity ratio method show that the sample doped with Mn and pure CuSe had the characteristics of ionization impurity scattering, and the scattering factor was 3/2. However, the deterioration in thermal conductivity was large, and a superior value needs to be obtained. The cyclic test results of high-temperature thermoelectric properties show that Mn doping can hinder Cu migration and improve its thermoelectric stability, which preliminarily verifies the feasibility of using the stable zirconia mechanism to improve the thermoelectric stability of CuSe.
硒化铜（CuSe）因其低成本、在地储量丰富以及高热电性能，是一种很有前景的热电（TE）材料。然而，CuSe最大的问题在于其化学性质不稳定。特别是在电场或梯度温度场的作用下，材料内部铜离子的化学势会增加。当外部场强足够大时，材料负极一端铜离子的化学势达到元素铜的化学势。在这些条件下，铜离子必然会析出，导致CuSe不稳定，使其不适用于相关应用。在本研究中，我们通过真空熔炼退火制备了CuMnSe（x = 0、0.02、0.04和0.06）系列块状材料，并通过放电等离子烧结（SPS）进行烧结。我们研究了锰掺杂对CuSe的组成、微观结构、能带结构、散射机制、热电性能和稳定性的影响。结果表明，锰掺杂可以调节载流子浓度，促进β相结构的稳定，并改善CuSe的电学性能。当x = 0.06时，CuMnSe在873 K时的最高功率因数（）值为1.62 mW m K。基于电导率比法的载流子散射机制分析结果表明，掺杂锰的样品和纯CuSe具有电离杂质散射的特征，散射因子为3/2。然而，热导率的恶化较大，需要获得更高的 值。高温热电性能的循环测试结果表明，锰掺杂可以阻碍铜的迁移并提高其热电稳定性，这初步验证了利用稳定氧化锆机制提高CuSe热电稳定性的可行性。
