Crystal Research and Technology
Cryst. Res. Technol. 35 (2000) 713 - Abstract -

N. D. Zakharov, P. Werner, I. P. Zibrov*, V.P. Filonenko**, M. Sundberg***

Max-Planck-Institute for Microstructure Physic, Halle/Saale, Germany
*Institute of Crystallography, Russian Academy of Sciences, Moscow, Russia
**Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk, Russia
***Department of Inorganic Chemistry, Arrhenius laboratory, Stockholm University, Sweden

Structural Studies of Calcium Tungsten Bronzes, CaxWO3, Formed at High Pressure

The structure of a new calcium intergrowth tungsten bronze, CaxWO3, prepared at P = 80 kbar and T = 1670 K, has been studied by high-resolution transmission electron microscopy and supplementary techniques. The unit-cell dimensions, determined from X-ray powder data, are: a = 10.1500(9), b = 7.4232(7) and c = 3.7915(4) Å. The crystal structure is of (n)-ITB type with n = 2. It is isotypic with those recently reported for the RExWO3 bronzes (RE = Pr and Nd) prepared at P = 50 kbar. Combined electron diffraction and energy-dispersive X-ray spectroscopy (EDX) studies of thin crystallites showed that the hexagonal tunnels were less than half-filled with Ca atoms (x ~ 0.07+-0.01). Electron diffraction patterns revealed ordered superstructures of (2)-ITB as well as an order–disorder transformation under the intense electron beam. A calcium bronze (Ca~0.12WO3) with an hexagonal tungsten bronze structure (HTB) was also observed in the sample.

Keywords: calcium tungsten bronze, high-resolution transmission electron microscopy, high-pressure synthesis, microanalysis, crystal structure, order-disorder


The full text of this paper in pdf-Format:

If you came directly to this page, click this symbol to go to the homepage of CRT.