Bond Angle Study of Self-compensating Y1−xCaxBa2−xLaxCu3Oz System

Single-phase samples of a self-compensating Y1−xCaxBa2−xLaxCu3Oz system were synthesized through a solid-state reaction method with x<0.4. The structure of all samples were characterized by X-ray diffraction and refined by the Rietveld method. Superconducting properties have been investigated by the DC magnetization measurement. The critical temperature (Tc) decreases evidently with the increment of x although the carrier concentration remains constant in the samples for different doping level. Careful study of the chemical bonds in the crystalline lattice demonstrates that the Tc is closely correlated to four pairs of bond angles in the unit cell. The analysis indicates that crystalline structure is one of the important factors to high-Tc superconductivity, and its influence is independent of the carrier concentration.