Intergrowth tungsten bronze structures of PrxWO3, formed at 50 kbar: An HRTEM study

New praseodymium intergrowth tungsten bronzes, PrxWO3, of (n)-ITB structure type have been prepared by solid state reaction at P = 50 kbar and T = 157 0 K. The ordered members 2, 3, and 4 were identified by high-resolution tra nsmission electron microscopy. The structure of (2)-ITB was deduced from an electron micrograph, and the unit cell parameters were determined from the X-ray powder data: n 10.17 Angstrom, b = 7.418 Angstrom, and c = 3.790 Ang strom. The praseodymium content (0.04 less than or equal to x less than or equal to 0.1), corresponding to less than half-filled hexagonal tunnels in the ITB-structures, was found by combining electron diffraction and microan alysis studies of the same crystal fragments. An ordered superstructure, de signated (2)(5)(3)(3)-ITB, was also observed. (C) 1999 Academic Press.