X-ray diffraction of La1.8Ba0.2CuO4-y reveals two macroscopically segregated tetragonal (K2NiF4-type) phases of nearly identical lattice parameter. Many peaks show additional broadening upon cooling. This broadening is consistent with a spontaneous monoclinic distortion, with an onset temperature of 150 K, and is possibly relevant to the superconducting properties. Small single crystals of 70 m diameter within the powder aggregate are also studied and show a similar two-phase constituency and a resolvable peak splitting at low temperature.
All Science Journal Classification (ASJC) codes