The Fine Structure of YCuO2+x Delafossite Determined by Synchrotron Powder Diffraction and Electron Microscopy

✍ Scribed by G. Van Tendeloo; O. Garlea; C. Darie; C. Bougerol-Chaillout; P. Bordet

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 736 KB
• Volume: 156
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.9018

✦ Synopsis

YCuO 2 delafossite crystallizes into two stacking variants; hexagonal 2H or rhombohedral 3R, depending on the preparation conditions. The structure of the fully oxygenated material YCuO 2.50 has been determined as orthorhombic (a o ‫؍‬ 6.1961 A s ; b o ‫؍‬ 11.2158 A s ; c o ‫؍‬ 7.1505 A s ; space group Pnma). The structure is based on the hexagonal 2H structure (a o ‫؍‬ a H (3; b o ‫؍‬ c H ; c o ‫؍‬ 2a H ). Upon incomplete oxidation, a di4erent YCuO Z phase with ideal composition YCuO 2.33 and lattice parameters a H (3, a H (3, c H is also formed. Di4raction patterns are often very complex because of the presence of planar defects and intergrowth of both phases. Under electron beam irradiation, oxygen is released from the structure and one phase gradually transforms into the other.