✍ Scribed by C. Greaves; P.R. Slater
No coin nor oath required. For personal study only.
Nb and Ta substitutions in YBa2Cu307 and related phases have been examined in an attempt to synthesise phases of formula LBa2Cu2MOs (L = rare earth, M = Nb, Ta), in which the square planar Cu I sites of the YBa2Cu307 structure are occupied by M, and complete oxygen occupancy in the basal plane of the unit cell provides octahedral coordination for M. Single phase materials of composition LaHBat.9Cu2.1M0.908 have been successfully synthesised and their structures examined by powder X-ray and neutron diffraction. The location of M atoms solely in the Cul sites with octahedral symmetry is confirmed. The square planar CuO4 units, which link the layers of square pyramidal CuO5 units in YBa2Cu307, are replaced by MO6 octahedra in the new phases. This new link provides interesting scope for the synthesis of new phases with potential as superconductors, but to date no superconducting properties have been confirmed, possibly due to insufficient oxidation within the layers of CuO5 square pyramids.
📜 SIMILAR VOLUMES
Properties of a series of Zn-cloped YBa2Cu307-samples prepared under identical cond tions have been studied by powder neutron diffraction (20 K, 270 K), powder X-ray-and electron diffraction (290 K), by measurements of specific heat Cp (1.4 K-300 K) and Meissner effect (4 K -100 K). Tc decreases lin
The high-temperature structural behavior of the layered intergrowth phase Bi 4 TaO 8 Cl, belonging to the SilleH n-Aurivillius family, has been studied by powder neutron di4raction. This material is ferroelectric, space group P2 1 cn, at T C (640 K. An order8 disorder transition to centrosymmetric s