Improvement in the Thermoelectric Figure of Merit by La/Ag Cosubstitution in PbTe

K. Ahn, C.P. Li, C. Uher, M.G. Kanatzidis



 The strongly anisotropic thioarsenates A(3)Ta(2)AsS(11) are stabilized in a polysulfide flux. All compounds contain the same parallel (1)/(infinity)[Ta(2)AsS(11)(3-)] polymeric anionic chains, but the size of the alkali-metals has a profound effect on the packing of the chains. The K(+) or Rb(+) favor noncentrosymmetric packing of the chains, whereas the larger Cs(+) favors the centrosymmetric packing. The chains feature the combination of two asymmetric units [Ta(2)S(11)] and [AsS(3)] and exhibit strong nonlinear optical (NLO) second harmonic generation (SHG) response. Polycrystalline samples exhibit is up to approximately 15 times stronger SHG than that of commercially used AgGaSe(2).

Link to article - American Chemical Society

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