Low-Temperature Structure in La1.85Sr0.15CuO4

Research on the crystal structure of a single crystal of La1.85Sr0.15CuO4-δ was performed at low temperatures by X-ray diffraction technique. New structural phase transitions were found above T c. Lowering the temperature, the (200) reflection peak splits into three peaks along the [010] direction at T 1∼220 K; on further cooling, these peaks split into several peaks at T 2∼145 K. The crystal structures of the new phases are discussed.