材料期刊网

采用钽管封装熔炼和热压烧结技术制备了Ca2Si(1-x)Snx (x=0, 0.02, 0.04, 0.06)热电材料.利用X射线衍射(XRD)对样品的物相结构进行了表征,XRD结果表明,Ca2Si(1-x)Snx块体材料的XRD图谱与Ca2Si的XRD图谱对应一致,但所有样品中都出现Ca5Si3衍射峰.当掺杂量Sn为0.06时,样品Ca2Si(1-x)Snx (x=0.06)的XRD图谱中还出现了CaSn3相.在室温下测试了样品的霍尔系数,在300~873 K温度范围内研究了Sn掺杂对Ca2Si电导率和Seebeck系数的影响,随着Sn掺杂浓度的增加,电导率逐渐增大,Seebeck系数则减小.分析了Sn掺杂对Ca2Si晶格热导率和热导率的影响,Sn掺杂浓度为x=0.02和x=0.04时,晶格热导率减小,从而对热导率有所优化,其中Ca2Si(1-x)Snx (x=0.02)的热导率得到明显地改善,在300~873 K温度范围内,其热导率都低于Ca2Si的热导率.在550~873 K温度范围内,Ca2Si(1-x)Snx (x=0.02)表现了较高的ZT值,873 K时的最大ZT值为0.22.

Ca2Si(1-x)Snx (x=0, 0.02, 0.04, 0.06) thermoelectric materials were fabricated by melting in tantalum tube and hot pressing technique.Phase structures of the samples were analyzed by means of x-ray diffraction (XRD).The results show that the characteristic peaks of the bulk Ca2Si(1-x)Snx can be indexed into Ca2Si.The peak of Ca5Si3 exists in the XRD patterns of all the bulk Ca2Si(1-x)Snx samples.The peak of CaSn3 can be found in the XRD patterns of the bulk Ca2Si(1-x)Snx(x=0.06) sample.Hall coefficients of the samples were measured at room temperature.The electrical conductivity and Seebeck coefficient of Ca2Si(1-x)Snx alloys were studied in the temperature range of 300-873 K.The electrical conductivity of the Sn-doped samples increases with increasing Sn concentration, while the Seebeck coefficient of the Sn-doped samples decreases.The lattice thermal conductivity and total thermal conductivity of the Ca2Si(1-x)Snx samples were investigated in the temperature range of 300-873 K.Compared with the Ca2Si sample, Sn-doping (x=0.02, 0.04) results in the decrease of the lattice thermal conductivity, especially Ca2Si(1-x)Snx with x=0.02.The Ca2Si(1-x)Snx with x=0.02 sample exhibits the lowest thermal conductivity within the whole testing temperature range.The ZT values of Ca2Si(1-x)Snx with x=0.02 sample have an enhancement in the temperature range of 550-873 K by contrast with those of the Ca2Si sample.The maximum ZT value was 0.22 at 873 k, which was observed for the Ca2Si(1-x)Snx with x=0.02 sample.