Compositionally controlled metal–insulator transition in Tl2−xInxTeO6

Tl2TeO6 and In2TeO6 are both known to crystallize in the Na2SiF6-type structure. We find Tl2TeO6 is metallic, whereas In2TeO6 is an insulator. We have prepared a complete Tl2−xInxTeO6 series in a search for a compositionally controlled metal–insulator transition that might be expected if a complete solid solution can be obtained. Unit cell edges and volume vary monotonically with no indication of a miscibility gap. The metal–insulator transition occurs at an x value of about 1.4, which can be rationalized on a percolation model. No superconductivity could be detected down to 5 K.