Abstract
A group of researchers belonging to a few different universities has been formed to study Ba2YCu3O7-δ and related oxides.from various aspects and to develope new systems. Phase diagram of the Ba-Sr-Y-Cu-O system has been drawn and microstructure formed on cooling at various rates from the molten state, preparation of fine powder, complex susceptibility of powder and sinterd pellets, microscopic structure observed by TEN and Mossbauer spectroscopy of 57Fe impurity, surface chemical composition, and effects of the application of high oxygen pressure (-108Pa) have been studied for the Ba2YCu3O7-δ, and some related systems. For the developement of new systems, we are trying to prepare two dimensional lattices of MO2 (M: transition metal ions with S=1/2) sandwitched by or sandwitching acceptor layers containing highly charged transition metals.
