A thermoelectric material includes a filled skutterudite crystal structure having the formula G.sub.yM.sub.4X.sub.12, where i) G includes at least two rare earth elements and an alkaline earth element, ii) M is cobalt, rhodium, or iridium, and iii) X is antimony, phosphorus, or arsenic. The subscript "y" refers to a crystal structure filling fraction ranging from about 0.001 to about 0.5.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made in the course of research and/or development supported by the U.S. Department of Energy, under Government Contract No. DE-FC26-04NT42278. The U.S. government has certain rights in the invention.