Strategies To Stabilize New Oxides in the Srn+1(CoTa)nO3n+1 Ruddlesden-Popper Homologous Series

• Published in: Chemistry : a European journal 2007-01, Vol.13 (3), p.910-915
• Main Authors: Boulahya, Khalid, Parras, Marina, González-Calbet, José María
• Format: Article
• Language: English
• Subjects: high resolution electron microscopy; layered compounds; perovskite phases; solid-state structures; X-ray diffraction
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200600882

Two new oxides of the Ruddlesden–Popper series have been isolated and structurally characterized in the Sr‐Co‐Ta‐O system. X‐ray and electron diffraction and high‐resolution electron microscopy show that polycrystalline Sr3CoTaO7 constitutes the n=2 member of a new Srn+1(CoTa)nO3n+1 homologous series, the essential feature of which is the existence of two connected Co/Ta octahedral layers, separated by Sr atoms. Sr2CoTaO6, the n=∞ member of the series, shows a particular short‐range ordering of Co and Ta at the octahedral sites leading, as shown by high‐resolution electron microscopy, to the disordered intergrowth of simple and double perovskite type domains. Strategies to stabilize new oxides of this series are discussed. Results of a microstructural study, obtained by means of high‐resolution electron microscopy, show a crystal that is composed of the intergrowth of n=2, 3, and 5 members (shown here) of the Ruddlesden–Popper homologous series of chemical composition Srn+1(Co0.5Ta0.5)nO3n+1.