“…The Nb(Ta)O 6 octahedral layer is a new kind of intermediary layer for high-T c copper oxides, and the Nb and Ta charges of +5 are the highest yet on cations to be accommodated in such a layer. The (Nb, Ta-O) octahedral layers join (Tl-O) and (Pb, Cu-O) octahedral layers, (PbOCu-PbO) and (Bi-O) distorted pyramids, Cu-O sticks and chains, and possibly GaO 4 tetrahedra [6,7], as building blocks for new materials. The octahedra in the new layer share corners, not edges as [8,9] and the expected optimal concentration for superconductivity, x 0.6 (which corresponds to a nominal hole concentration of 0.2/Cu).…”