PRESSURE EFFECTS ON SUPERCONDUCTIVITY AND STRUCTURAL PHASE-TRANSITIONIN LA1.8-XND0.2BAXCUO4

The structural transition at T-1(similar to 110 K) of La1.8-xNd0.2BaxC uO4 (x=0.1) disappears above 1GPa, but the superconducting critical te mperature T-c increases monotonically with pressure over the whole pre ssure range examined (0 less than or equal to P less than or equal to 2GPa). On the other hand, the structural transition for x=0.125 persis ts up to, at least, 2GPa, though it jumps to the temperature T(simila r to 60 K), where the charge (hole) ordering occurs, at pressures abov e 1.5GPa The structural change for x=0.125 is appreciably depressed at P greater than or equal to 1.5GPa and T-c is largely restored.