Displacement Waves in La2CuO4-δ and La1.85Sr0.15CuO4-δ

Abstract
Structural investigation of orthorhombic La2CuO4-δ and La1.85Sr0.15CuO4-δ was carried out by means of X-ray and neutron diffraction on the basis of the space group Cmmm. The periodic expansion/contraction type distortion of CuO6 octahedra was found in both orthorhombic compounds. The distortion is nearly one-dimensional in La2CuO4-δ but is two-dimensional in La1.85Sr0.15CuO4-δ. The existence of a charge-density wave, CDW, with a wave vector q CDW=(0 0 c *) is highly possible in the structures.