Thermoelectric properties of Ln(2-x)Bi(x)Ru(2)O(7) pyrochlores (Ln = Nd and Yb)

The pyrochlore ruthenates Ln(2-x)Bi(x)Ru(2)O(7), (Ln=Nd and Yb, x=1 and 0.6 ) have been synthesized and their thermoelectric properties have been studi ed from room temperature to 1000 K. These samples show the metallic-like re sistivity (rho)-temperature (T) behaviors (except Yb2-xBixRu2O7) and their rho increases with the x values, while their Seebeck coefficients (S) are n ot sensitive to the x values. Although the S of the Nd-system samples is al most the same as that of the Yb-system ones, the rho of the former is less than that of the latter. It indicates that the Nd-system samples have highe r thermoelectric power factors than Yb-system ones. The rho, S and power fa ctor of NdBiRu2O7 at 1000 K is 1.5 m Omega cm, 35 muV/K and 0.8 x 10(-4) W/ mK(2), respectively. (C) 2001 Elsevier Science B.V. All rights reserved.