Synthesis And Thermoelectric Properties Of RXTe3

A new method combining mechanical alloying method (MM) with spark plasma sintering(SPS) technique was used to synthesize layered rare earth ternary thermoelectric materialsRXTe3(R=La, Ce, Nd; X=Bi, Sb). Followings are the main results:(1) NdBiTe3、La0.3Ce0.7BiTe3、La0.7Ce0.3BiTe3and NdSbTe3ternary alloys were synthesizedby solid state reaction method using high purity La、Ce、Bi、Sb、Nd and Te. Measured XRDspectra indicate four samples have Bi2Te2S-type layered structure. However, NdBiTe3andNdSbTe3contains minor content of NdTe2，while La0.7Ce0.3BiTe3and La0.3Ce0.7BiTe3containminor content of LaTe2。(2) In order to reduce the binary impurities, the products of high speed solid state reactionball mill were milled for different period of time. XRD spectra demonstrate milled samples havesingle phase of layered Bi2Te2S-type crystal structure. As the milling time increases, the binaryrare-earth phases were quickly reduced. Compared with the synthesis methods of literature, oursynthetic method has the advantage of simple and quick.(3) Further analysis of the XRD patterns of LaBiTe3, La0.7Ce0.3BiTe3, La0.3Ce0.7BiTe3, andCeBiTe3, it was found that with increasing content of the Ce, the peak of (0,0,15) obviouslymoves towards high angle, which demonstrates our preparation of the synthesis of mixed rareearth compounds.(4) With the TTO module of physical property measurement system (PPMS), resistivity,thermal conductivity and Seebeck coefficient were measured simultaneously at temperatures of2–400K. The Seebeck coefficient of NdSbTe3is positive and with a maximum of483μV K1,while Seebeck coefficients of La0.7Ce0.3BiTe3、La0.3Ce0.7BiTe3and NdBiTe3are negative. The signof Seebeck coefficients prove that NdSbTe3is a P-type semiconductor, while La0.7Ce0.3BiTe3、La0.3Ce0.7BiTe3and NdBiTe3is a N-type semiconductor.(5) The resistivity of La0.7Ce0.3BiTe3、La0.3Ce0.7BiTe3and NdBiTe3were measured with4-prope method in magnetic field. They show magneto resistance effect.