STRUCTURE OF BA2INCUOY - A NEW LAYERED CUPRATE WITH A BLOCKING LAYER OF BAINOY PEROVSKITE

A new blocking layer with an a-axis length of 4.18 Angstrom, BaInOy, w as found. The blocking layer supplies an apical oxygen to the CuO2 lay er and produces an oxygen vacancy in the in-plane of the CuO2 layer. B y matching the blocking layer with the CuO2 layer, a new layered cupra te, Ba2InCuO4.53, was prepared. Its space group was Pmmm with lattice parameters of a = 4.1820(6) Angstrom, b = 4.1820(5) Angstrom and c = 8 .0889(9) Angstrom. The fact that the a- and b-axis lengths of Ba2InCuO 4.53 compound are much longer than those of the other cuprate compound s is explained by the existence of an oxygen vacancy in the CuO2 Its r esistivity at room temperature was as large as 28.8 M Omega cm. The in sulating property probably comes from the existence of the oxygen vaca ncy in the CuO2 layer.