Dimensionality of the oxidic layers in pnictide oxides and transition metal p‐element ordering in tetrelides and pnictides

Abstract

Pnictide oxides exhibit a rich crystal chemistry, which is much more than the ZrCuSiAs structure of LaFeAsO, the mother‐structure of the 1‐1‐1‐1 materials. The present micro‐review focuses on different dimensionalities in the oxidic and the pnictide substructures, largely extending the structural building units. The second part concerns BaAl4/ThCr2Si2 superstructures, which extend the crystal chemistry of BaFe2As2. Key parameters for superstructure formation are either an ordering of the transition metal and p‐element atoms (coloring) or an ordering of vacancies.