New 1212-Molybdo-Cuprate phases using High pressure and high temperature synthesis

New 1212- type Molybdo-Cuprates of with composition Mo0.5Cu0.5Sr2RECu2O7.5 (RE = Rare Earth) have been prepared by High Pressure and High Temperature (HPHT) synthesis. Their crystal structures are characterized by combining the X-Ray/Neutron powder diffraction and electron diffraction techniques. All the materials show tetragonal symmetry, crystallizing in the P4/mmm space group (S.G.). The chain oxygens are randomly distributed in the two different oxygen sites, which are not completely filled and the defect induced by oxygen vacancies in fact makes the chain fragmented and disordered. The microstructure of these compounds is interpreted by a well-known diagonal cell √2ap × √2ap × 3ap, as confirmed by the Electron diffraction (ED) and transmission electron microscope (TEM). X-ray photoelectron spectroscopy (XPS) studies show the predominance of the non magnetic MoVI state over the MoV one. At the same time oxidation state of copper is found to be dominated by CuII.