S. C. Moss

X-ray search for charge-density-wave satellites in single-crystal Ba1-xKxBiO3.

Two electrochemically grown single crystals of Ba[sub 1[minus][ital x]]K[sub [ital x]]BiO[sub 3] were investigated on the insertion line X25 at the National Synchrotron Light Source: one in the middle of the semiconducting regime ([ital x]=0.23) studied at 300 K and one near the metal-semiconductor, or cubic-orthorhombic, boundary ([ital x]=0.35) studied at 300 and 11 K. The proposed charge-density-wave satellites, seen along [l angle]110[r angle] directions with electron diffraction, have been attributed previously to electron-beam irradiation effects even though their positions seem to vary smoothly with K content. A careful x-ray search in all equivalent [l angle]110[r angle] directions of the pseudocubic reciprocal lattice revealed no satellite structure in either of the samples. We therefore conclude that the reported electron-diffraction results are indeed induced through electron-beam effects and discuss possible interpretations of our observed absence of these satellites in the as-grown crystals and their dependence on electron-beam irradiation.