Superconductivity and electronic instability at high pressure in Sc5Co4Si10-type compounds

The variation of the superconducting transition temperature (T/sub c/) with hydrostatic pressure up to 23.7 kbar is reported for eleven ternary silicides and germanides with the Sc5Co4Si10-type structure. Most of these compounds display a modest linear depression of T/sub c/ with pressure (dT/sub c//dpapprox.10-5 K/bar); however, two materials, Lu5Ir4Si10 and Lu5Rh4Si10, undergo a discontinuous transformation to a state with a significantly higher T/sub c/ above a critical pressure of about 20 kbar. For Lu5Ir4Si10, the pressure-enhanced T/sub c/ of 9.12 K is the highest transition temperature reported for this class of compounds