n-to-p Transition on K2Bi8-xSbxSe13 Series

beta-K₂Bi₈Se₁₃ and its solid solutions have been found to be interesting for thermoelectric investigations mainly due to their low thermal conductivity and highly anisotropic electrical properties. Solid solution series of the type K ₂Bi_8-xSb_xSe₁₃, K_2-x Rb_xBi₈Se₁₃ as well as K₂ Bi₈Se_13-xS_x has been studied. Interestingly, K₂Bi_8-xSb_xSe₁₃ presents both n- and p-type of character depending on the Sb concentration in the lattice. In this work, the n-to-p transition with Sb concentration is presented. The Seebeck coefficient is discussed as a function of x and the transition at room temperature appears at the stoichiometric region of x ~ 6. The transition temperature for the members of the series increases with Sb incorporation in the lattice and this can be attributed to the band gap increase