Structure and thermoelectric properties of Me-substituted In4Sn3O12, Me = Y and Ti

Me-substituted In4Sn3O12, Me = Y and Ti, have been prepared by high-tempera ture solid state reaction and subsequent quenching. The structure of these compounds was analyzed using the Rietveld method. Y substitution causes an enlargement of the lattice constant whereas Ti substitution diminishes the size of the unit cell. The thermoelectric transport properties of Me-substi tuted In4Sn3O12-delta were investigated over a temperature range of 300 to 1273 K. The electrical conductivity, sigma, decreases with increasing subst itution level, whereas the absolute value of the Seebeck coefficient, S, in creases. Highly Ti-substituted compounds at high temperatures exhibited max imum values of the power factor S(2)sigma for thermoelectric power generati on of 1.9 10(-4) W K-2 m(-1) during annealing under an argon atmosphere con taining less than 10 ppm oxygen. Relatively low thermal conductivities of t he sintered pellets of the compounds, ca. 1.3 W m(-1) K-1 at 1273 K, lead t o the largest value of the thermoelectric figure of merit Z = S(2)sigma/kap pa = 1.5 10(-4) K-1 as the maximum value at 1273 It. (C) 2000 Academic Pres s.