STRUCTURE AND OXYGEN STOICHIOMETRY IN COMPLEX NEODYMIUM STRONTIUM COBALT COPPER OXIDES - [NDSRCO1-XCUXO4-Y]

Compounds from the solid solution NdSrCo1-xCuxO4-y (0 less-than-or-equ al-to x less-than-or-equal-to 0.9) have been prepared and characterise d with powder X-Ray and neutron diffraction together with thermogravim etric analysis. The materials have been shown to adopt the K2NiF4 stru cture (spacegroup 14/mmm). Variations of the a- and c- parameters show a complex behaviour with increasing copper content. At all values of x, the average transition-metal oxidation is high. The changes in cell parameters are discussed in terms of oxygen stoichiometry and transit ion-metal oxidation state from the perspective of the Brown bond valen ce calculation theory.