X-Ray and Electron Diffraction Study of the Tetragonal Sodium Tungsten Bronze, Na0.10WO3, with Distorted Perovskite Structure

✍ Scribed by S.T. Triantafyllou; P.C. Christidis; Ch.B. Lioutas

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 447 KB
• Volume: 133
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7513

✦ Synopsis

The crystal structure of the tetragonal sodium tungsten bronze, Na0.10WO3, was investigated by single-crystal X-ray and electron diffraction methods. The average structure has space group P4/nmm and cell constants aav ‫؍‬ 5.2492(5) A > , cav ‫؍‬ 3.8953(4) A > , and Z ‫؍‬ 2. The superstructure has space group very probably P4 and cell constants as ‫؍‬ 7.423(3) A > , cs ‫؍‬ 7.791(1) A > , and Z ‫؍‬ 8. Full-matrix least-squares refinements resulted in a conventional R value of 0.041 [86 observed unique reflections, I'2 (I)] for the average structure and an R value of 0.086 [537 observed unique reflections, I'2 (I )] for the superstructure. The general features of the average structure, which is of distorted perovskite type, are the same as those reported earlier (A. Magne´li, 1951. Acta Chem Scand. 5, 670). The two axial bonds of the WO6 octahedron are not equal (1.95 A > ) as observed in the previous work but have significantly different lengths [1.63(6) and 2.27(6) A > ]. The superstructure, reported for the first time, results from the average structure by the combined effects of tilting of the WO6 octahedra about c leading to a doubling of this axis (cs ‫؍‬ 2cav) and of shape deformation of these octahedra in the ab plane leading to a supercell in this plane with as ‫؍‬ (2aav .