Crystal Structure of a Modulated Composite Structure with Two Subsystems: Ba1.1064CoO3

✍ Scribed by A. El Abed; S.E. Elqebbaj; M. Zakhour; M. Champeaux; J.M. Perez-Mato; J. Darriet

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 456 KB
• Volume: 161
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9314

✦ Synopsis

The structure of Ba 1.1064 CoO 3 has been solved in the (3 ؉ 1)dimensional formalism. The structure is described as a modulated chain composite with two subsystems, [CoO 3 ] and [Ba], respectively. The superspace group is R-3m(00 )0s with a ‫؍‬ 9.8842(20) A s , c ‫؍‬ 2.4785(12) A s , and q ‫؍‬ 0.5532(4) c* (Z ‫؍‬ 3). A saw-tooth function was used to model both the occupational and displacive modulations. Each atomic saw-tooth function is de5ned by its center xL 4 along the fourth dimension, its width ( ), and the maximum amplitude of the displacive modulation ( ). The paper describes how, as a 5rst approximation, the columns (CoO 3 ) can be mainly described by a single free parameter, based on the height di4erence of the trigonal prisms and octahedra that constitute the transition metal chains. As a result, this superspace formalism requires only a small number of variables to be re5ned, compared to the conventional superstructure description.