PRESSURE EFFECT ON ANOMALOUS SUPPRESSION OF T-C AROUND X=1 8 IN LA2-XBAXCUO4 AND LA1.8-XND0.2BAXCUO4/

In La2-xBaxCuO4 (LBCO) and La1.8-xNd0.2BaxCuO4 (LNBCO), the low-temper ature structural change at T-1 (=60-110K), resulting from tilt of the CuO6 octahedra, is easily suppressed at high pressures. However, the s tructural change of LNBCO (x=0.125) remains up to 2GPa though it jumps from T-1 (similar to 110K) to T (similar to 60K), where the electric resistivity rho begins to upturn, at 0-1.5GPa. The upturn of rho is a lso suppressed at high pressures, and the superconducting critical tem perature T-c is fully restored except in a very narrow x-range around x=0.125. The T-c for x approximate to 0.125 is appreciably lower at 2G Pa than those for other Ba-contents.