Investigation of superlattices in Ksub(x)WO3 in relation to electric transport properties

Single crystals of Ksub(x)WO3 were investigated with electron microscopy and X-ray diffraction methods. In most cases deviations from the hexagonal tungsten bronze structure in terms of commensurate and apparently incommensurate superlattices were observed. The commensurate superlattices in the a-b plane of the hexagonal lattice were, for most compounds, relatively simple, resulting in either an orthohexagonal unit cell or a hexagonal unit cell with two or four times the volume of the tungsten bronze structure, respectively. The 'incommensurate' superlattice rows in the c direction indicated a periodicity of 50 to 250 A or more, depending in part on the crystal composition and temperature. Several different superlattice phases were observed. Diffraction patterns of Rbsub(x)WO3 showed only reflections of the regular tungsten bronze structure. (orig./TWO)