Crystal structures of the triple perovskites Ba₂K₂Te₂O₉ and Ba₂KNaTe₂O₉, and redetermination of the double perovskite Ba₂CaTeO₆.

ABSTRACT: Single crystals of Ba₂K₂Te₂O₉ (dibarium dipotassium nona-oxidoditellurate), (I), Ba₂KNaTe₂O₉ (dibarium potassium sodium nona-oxidoditellurate), (II), and Ba₂CaTeO₆ (dibarium calcium hexa-oxidotellurate), (III), were obtained from KNO₃/KI or KNO₃/NaNO₃ flux syntheses in platinum crucibles for (I) and (II), or porcelain crucibles for (III). (I) and (II) are isotypic and are members of triple perovskites with general formula A₂^[12co]A'^[12co]B₂^[6o]B'^[6o]O₉. They crystallize in the 6H-BaTiO₃ structure family in space-group type P6₃/mmc, with the A, A', B and B' sites being occupied by K, Ba, Te and a second Ba in (I), and in (II) by mixed-occupied (Ba/K), Ba, Te and Na sites, respectively. (III) adopts the A₂^[12co]B'^[6o]B''^[6o]O₆ double perovskite structure in space-group type Fmm, with Ba, Ca and Te located on the A, B' and B'' sites, respectively. The current refinement of (III) is based on single-crystal X-ray data. It confirms the previous refinement from X-ray powder diffraction data [Fu et al. (2008). J. Solid State Chem.181, 2523-2529], but with higher precision.

SUBMITTER: Weil M 

PROVIDER: S-EPMC6038633 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature