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Influence of p- and n-type doping on the transport properties of the Nowotny chimney-ladder compounds RuAl2 and RuGa2

Published online by Cambridge University Press:  03 June 2011

V. Ponnambalam*
Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824-1226
Gloria Lehr
Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824-1226
Donald T. Morelli
Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824-1226
a)Address all correspondence to this author. e-mail:
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Nowotny chimney-ladder compounds RuAl2 and RuGa2 have been substituted with p- and n-type dopants to study the resistivity, Seebeck and Hall coefficients, and thermal conductivity of resulting compounds in the temperature range of 80–300 K. The resistivity and Seebeck coefficient suggest that these compounds are degenerate semiconductors. Hall measurements reveal that the carrier concentration has indeed been changed by an order of magnitude, particularly in p-type RuGa2 by substituting Cr and Mn. Compared to p-type samples, the resistivity is an order of magnitude larger for n-type samples, for a similar level of carrier concentration. Interestingly, the hole mobility is two to three orders of magnitude larger, reaching the highest value of ∼750 cm2/V·s. The electron mobility is temperature independent and is typically in the range of ∼1–4 cm2/V·s. Thermal conductivity shows characteristics of mixed scattering with impurity scattering contributing appreciably in heavily substituted compositions.

Copyright © Materials Research Society 2011

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