The Electronic Structure of Tantalum Oxynitride and the Falsification of α‐TaON

Abstract

Abstract We have performed electronic structure calculations from first principles (LDA & GGA, plane waves & muffin‐tin orbitals, pseudopotentials & all‐electron techniques) on the two reported polymorphs of TaON. For the experimentally well‐characterized β ‐TaON adopting the baddeleyite structure type, there is excellent agreement between all accessible observables despite the supposedly correlated character of an oxynitride phase. Concerning hexagonal α‐TaON proposed first in 1966, one finds tremendous contradictions between theory and experimentally reported data (molar volume, total energy differences, electronic transport etc.) In combination with the communicated X‐ray diffraction diagram, α‐TaON is considered an erroneous entry in the solid‐state chemical literature that needs to be removed from the crystallographic databases.