CU-NQR STUDY OF THE MAGNETIC-PROPERTIES OF Y1-XCAXBA2CU3O6

The study of the T dependence of the Cu(1) NQR line width in Y1-xCaxBa 2Cu3O6 allows us to demonstrate that the phase diagram of these compou nds is quite similar to that observed in La2-xSrxCuO4, with a disorder ed magnetic intermediate phase. The absence of variation of the NQR fr equency on the Cu(1) site shows that there is no direct correlation be tween T-c and the apical oxygen position. Measurements of the spin-lat tice relaxation time in the AF phase reveal a radically different beha vior of T-l(-1) with respect to LaSCuO samples.