Pb1-xSr4Fe2O9-δ: A Layered Iron Oxide Intergrowth of 1201- and 0201- Type Structures

✍ Scribed by S. Lucas; D. Groult; N. Nguyen; C. Michel; M. Hervieu; B. Raveau

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 597 KB
• Volume: 102
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1993.1004

✦ Synopsis

A new layered iron oxide, (\mathrm{Pb}{1-x} \mathrm{Sr}{4} \mathrm{Fe}{2} \mathrm{O}{9-\delta}), has been isolated for (0 \leq x \leq 0.2). Its structural model, which corresponds to a regular intergrowth of single (\left[\mathrm{SrFeO}{3{-\delta}}\right}{x}) perovskite layers with single ([\mathrm{SrO}]{x}) and double (\left[(\mathrm{SrO})\left(\mathrm{Pb}{1-r} \mathrm{O}\right)\right]{x}) rock salt layers, has been established by high resolution electron microscopy (HREM) and powder XRD. The existence of numerous defects-local variation of the nature of the cations, modulations of the atomic layers, and intergrowth defects interpreted as (\left[\mathrm{Sr}{3} \mathrm{Fe}{2} \mathrm{O}{7-6}\right]{x}) and (\left[\mathrm{Sr}{4} \mathrm{Fe}{3} \mathrm{O}_{10-8}\right]) layers-has been observed by HREM. The existence for (\mathrm{Fe}() III) of two " (5+1) " coordinations for (x=0), and of three coordinations for (x \neq 0) (two (5+1) and one pure pyramidal coordination) has been deduced from Mössbauer spectroscopy measurements. 1992 Academic Press, Inc.