摘要
开展了TiNiSn_(0.95)Sb_(0.05)热电块体材料的微波快速合成-烧结研究,并对样品的物相组成、电性能、热性能、微观结构和综合热电性能进行了测试和表征分析。相组成分析表明,采用微波固相合成在4~5min内即获得了单一相纯度相对较高的TiNiSn_(0.95)Sb_(0.05)合金,但存在少量杂质SnO_2、Ni_3Sn_2、Sb_2O_4;合成样品经20min微波烧结后,还存在少量Sn和Sb_2O_4。电性能分析表明,电阻率较低为2.7~5.3μΩm,从而对功率因子产生较大影响,功率因子最高为4042μWm~(-1)K~(-2)。热性能分析表明,TiNiSn_(0.95)Sb_(0.05)样品的热导率随着温度升高而降低,热导率最大为5.9Wm~(-1)K~(-1),晶格热导率仅为2.7~3.5 Wm~(-1)K~(-1),热性能良好。微观结构分析表明,微波烧结抑制了TiNiSn_(0.95)Sb_(0.05)晶粒长大TiNiSn_(0.95)Sb_(0.05)基体晶内和晶界分布有大量纳米晶粒,绝大部分属于晶内析出,且分布较均匀,少部分分布在晶界。综合热电性能ZT值随温度的上升显著增大,并在573~673K获得最大值0.44。
The rapid microwave synthesis and sintering of TiNiSn_(0.95)Sb_(0.05) bulk was studied.The phase composition and microstructure of samples were characterized by X-ray diffractometer(XRD) and transmission electron microscope(TEM),respectively.The thermoelectric properties i.e.Seebeck coefficient(S),electrical resistivity(ρ),and thermal conductivity(κ) were measured through Seebeck coefficient/resistance analysis system(S/RAs) and laser flash thermal analyzer(LFT).The results show that a relatively high purity single phase of TiNiSn_(0.95)Sb_(0.05) alloy is synthesized within 4~5 min in microwave field,with present of a small amount of impurity SnO_2,Ni_3Sn_2,Sb_2O_4.The variation trends of S,p and power factor with temperature were analyzed.The electrical resistivity is relatively low,2.7-5.3 μΩ·m.The highest power factor is 4042 μW·m~(-1)·K~(-2).The thermal conductivity is decreased with temperature,and its maximum value is 5.9 W·m~(-1)·K~(-1).The lattice thermal conductivity is merely 2.7~3.5 W·m~(-1)·K~(-1).The microstructure analysis shows that the growth of TiNiSn_(0.95)Sb_(0.05) grain is inhibited during microwave sintering.A large number of nanometer grains are precipitated in the interior of TiNiSn_(0.95)Sb_(0.05) grain and on the boundary.The calculated thermoelectric figure of merit(ZT) is rapidly increased with temperature,and a maximum ZT of 0.44 is achieved at 573~673 K.
引文
