Figure 3.

(a) Schematic diagram showing characteristics of carrier concentration dependence of thermoelectric-related parameters. (b) Carrier concentration at room temperature (shown in brackets) and temperature-dependent electrical conductivity of Bi_2−xLa_xO₂Se. The increased carrier concentration benefited from doping atoms leads to a significant enhancement in electrical conductivity [33]. Reproduced with permission from the American Ceramic Society. (c) Room temperature carrier concentration as a function of alloying concentration in the Bi₂Te_3−xSe_x series. The yellow region represents Bi_Te is the dominating defects while the blue region representing V_Te or V_Se is the dominating defects. Data are from [56, 58, 62]. (d) Temperature dependence ZT value of polycrystalline Bi₂Te_3−xSe_x series prepared via hot deformation [56]. Reproduced with permission from WILEY-VCH.