Friedel oscillations and charge-density waves pinning in quasi-one-dimensional conductors

We present an x-ray diffraction study of 2.8 at.% V-doped blue bronzes. At low temperature, we have observed both an intensity asymmetry of the ±2k F satellite reflections relative to the pure compound, and a profile asymmetry of each satellite reflections. The profile asymmetry is due to Friedel oscillation around the V substituant and the intensity asymmetry is related to the charge density wave (CDW) pinning. These two effects give access to the local properties of CDW in disordered systems, including the pinning and even the phase shift of Friedel oscillations.