Superconductivity of PrOs4Sb12 at pressures to 10GPa

Electrical resistivity measurements have been performed on the heavy fermion superconductor PrOs 4 Sb 12 between 0.3 and 300K at pressures up to 9.8 GPa. Zero resistivity due to superconducting state was observed at all pressures up to P = 9.8 GPa. With increasing pressure up to 2.0 GPa, superconducting transition temperature T c was linearly shifted to lower temperature at a rate of -0.16 K/GPa. Effect of pressure on T c became smaller on further pressurization, following that the value of T c was saturated to a constant value of 1.3 K at high pressure. While, the upper critical field H c2 was strongly suppressed by increasing pressure. H c2 at 9.8 GPa estimated from the onset temperature of superconducting transition was 0.91 T at 0.5K.