Crystal structure determination of Pb2Sr2YCu3O8+δ (δ=0, 1.67) by powder neutron diffraction

Crystal structures of Pb₂Sr₂YCu₃O_8+δ(δ=0.0 and 1.67) were determined by powder neutron diffraction. For δ=0, it had been indicated by powder X-ray diffraction that the structure was a monoclinic one. The R factors of the present analysis for the monoclinic structure were about 3/4 of those for the previous orthorhombic ones. The structure was almost the same as the previous X-ray result except z(O(2)). For the annealed phase, the tetragonal and the orthorhombic structures had been presented by X-ray diffraction and by neutron diffraction, respectively. The R factors of the present analysis for the orthorhombic structure were about 5/6 of those for the tetragonal structure. The distance between the Pb plane and the oxygen-deficient Cu plane was found to become larger in proportion to δ, though there occurs a phase separation in the low-δ region.