Carbonate: an alternative dopant to stabilize new perovskite phases; synthesis and structure of Ba3Yb2O5CO3 and related isostructural phases Ba3Ln2O5CO3 (Ln = Y, Dy, Ho, Er, Tm and Lu)

Abstract

In this paper we report the synthesis of the new layered perovskite oxide carbonate, Ba₃Yb₂O₅CO₃. This phase is formed when 3BaCO₃ : 1Yb₂O₃ mixtures are heated in air at temperatures ≤1000 °C, while above this temperature the carbonate is lost and the simple oxide phase Ba₃Yb₄O₉ is observed. The structure of Ba₃Yb₂O₅CO₃ was determined from neutron diffraction studies and consists of a tripled perovskite with double Yb–O layers separated by carbonate layers, the first example of a material with such a structure. Further studies showed that analogous Ba₃Ln₂O₅CO₃ phases could be formed for other rare earths (Ln = Y, Dy, Ho, Er, Tm and Lu). The results highlight the ability of the perovskite structure to accommodate carbonate groups, and emphasise the need to consider their potential presence particularly for perovskite systems prepared in lower temperature synthesis routes.