La_2O_3-SrO-CuO系平衡状態図について

概要

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Phase equilibrium in the La-Sr- Cu- O system has been studied mainly by the X- ray diffraction analysis. The equilibrium phase diagram of the La_2O_3-SrO- CuO system was drawn up at 1173 K in air. We found two new compounds ; Sr_3Cu_5O_x and La_4SrCu_5O_x. Sr_3Cu_5O_x has an orthorhombic structure with lattice parameters ; a = 3.956, b =13.412 and c =11.475 in A. U. It was confirmed that the K_2NiF_4-type oxide (La_<1-a>Sr_a)_2CuO_x is a solid solution of ≦a≦O0.5 in which the terminal compounds are La_2CuO_4 and LaSrCuO_4, respectively. In contrast with an orthorhombic La_2CuO_4 (a=O), (La__<1-a>Sr_a)_2CuO_x of 0.1≦a≦0.5 has a tetragonal structure. (La_<1-a>Sr_a)_2CuO_x. coexists with CuO, La_4SrCu_5O_x and La_2SrCu_2O_x for ≦a≦O0.05, 0.05≦a≦0.13 and 0.13≦a≦0.5, respectively. The dependence of lattice parameters of the solid solution (La_<1-a>Sr_a)_2CuO_x on a was also determined.
1988-04-01