THE SYNTHESIS AND CHARACTERIZATION OF A NEW FAMILY OF SINGLE-LAYER CUPRATES - LNBACUO2BO3 (LN=LA, PR, ND, SM, EU AND GD)

We have succeeded in preparing a new series of cuprate compounds with the composition of LnBaCuO2BO3 Where Ln = La, Pr, Nd, Sm, Eu and Gd. A s indicated by the X-ray powder (diffraction patterns and IR spectra, the structure of the compounds is built up by CuO2! planes and borate layers containing distinct BO3 groups. The in-plane Cu-O bond lengths were found to decrease from 1.971 angstrom to 1.936 angstrom when the ionic radii of the rare earth elements (from Ln = La to Ln = Gd) are decreased. Such a variation is equivalent to that found in the n-type superconducting Ln2CuO4 CoMpounds of the T'-structure. Although the Ln BaCuO2BO3 compounds possess the common feature of most high-T(c) cupra tes, we have failed in inducing superconductivity in this system yet.