Atomic radii in ternary adamantines

Abstract

Bonded radii are derived for eight electropositive and four electronegative elements from line plots of total valence electron densities [Jaffe and Zunger, Phys. Rev. B28, 5822 (1983); B30, 741 (1984)] for 10 ternary chalcopyrites, in order to aid in understanding the defect chemistry of such compounds. They scale well with tetrahedral sulphide crystal radii, when a spherical atom approximation is made, in which case they are significantly closer to these than to covalent tetrahedral radii, as illustrated for several ternary chalcogenides. Their derivation confirms that the electronegative elements in these tetrahedrally bonded ternaries are better described by tetrahedrally distorted spheres. Still, models using these radii are to be preferred over the usual ball-and-stick types. This is illustrated by a few examples concerning native defects and ion mobility in some ternaries.