A new family of high-TC superconductors (Ln1-xCex)2(Ba1-yLny)2Cu3O10-z (Ln : Nd, Sm, Eu, Gd) has been found by resistivity and magnetization measurements. The highest onset transition temperature is about 48K. The structure is proposed on the basis of electron diffractions and Rietveld analysis of powder X-ray diffraction data.
