BiCuSeO硒氧化合物的微波超快合成及Bi,Cu空位对化合物电输运性能的影响

Microwave ultra-fast synthesis and influence of Bi/Cu vacancies on electrical transport properties of BiCuSeO oxyselenides

采用微波加热4 min成功合成了Bi_(1-x)CuSeO和BiCu_(1-y)SeO(x,y=0,0.02,0.03,0.04,0.05),随后在650℃下采用放电等离子烧结5min获得相对致密度约95%的热电块体,并对它们的物相组成、微观结构、电输运性能进行系统研究。X衍射分析表明,样品衍射峰与四方晶系BiCuSeO标准卡片吻合,但部分样品中含有少量杂质;微观结构分析结果表明,空位样品晶粒呈针状、条状,平均晶粒尺寸约为2~4μm;电性能分析表明,虽然空位样品的塞贝克系数相比非空位BiCuSeO样品的略有降低,但空位处理显著提高了样品的导电性,其中Bi空位浓度对Bi_(1-x)CuSeO电阻率的影响较不规律,BiCu_(1-y)SeO样品电阻率随Cu空位浓度提高呈规律性降低、导电性增强。综合来看,空位处理可以大幅提高样品综合电性能即功率因子,其中Bi0.96CuSeO的功率因子最高达到395.1μW/(K2·m),BiCu0.95SeO功率因子最高达到481.5μW/(K2·m),分别为非空位BiCuSeO样品最高功率因子的2.1倍和2.5倍。

The series of oxyselenides thermoelectric compounds Bi1-xCuSeO and BiCu1-ySeO(x, y=0, 0.02, 0.03, 0.04, 0.05) were successful synthesized in 4 min via microwave heating for the first time, and the corresponding bulks were subsequent fabricated with spark plasma sintering at 650 ℃ for 5 min. The phase composition, microstructure and electrical transport properties were investigated. The analysis of XRD patterns show that the diffraction peaks for all samples are matching to tetragonal BiCuSeO standard card. However, some samples contain small amounts of impurities. The analysis of microstructure shows that the grains of samples with vacancy show needle-like and strip-like, with average grain sizes of about 2-4 μm. The analyses of electrical transport properties show that the seebeck coefficients of samples with vacancy are slightly lower than that of non-vacancy BiCuSeO, nevertheless, the vacancy treatment significantly improves the conductivity. Bi vacancy concentration has an irregular influence on the resistivity of Bi1-xCuSeO samples, and the resistivity of BiCu1-ySeO samples decrease regularly with the increase of Cu vacancy concentration, respectively. In general, the vacancy treatment can greatly improve the comprehensive electrical performance, namely, enhance the power factor, the maximum power factors for Bi0.96 CuSeO and BiCu0.95 SeO are 395.1 and 481.5 μW/(K2·m), respectively, which are 2.1 times and 2.5 times compared to that of the non-vacancy BiCuSeO.