Superconductivity of MRhSi (M=Ti, Zr and Hf) prepared at high pressure

Using a wedge-type cubic-anvil high pressure apparatus, ternary rhodium silicides MRhSi (M=Ti, Zr and Hf) and alloys ZrRh 1− x Ru x Si ( x=0.1, 0.3 and 0.5) with a Co 2P-type orthorhombic structure have been prepared by reaction of stoichiometric amounts of each metal and silicon powders at around 4 GPa and above 1200°C. The electrical resistivity and the d.c. magnetic susceptibility of the ternary rhodium silicides and the alloys have been measured at low temperatures. Superconducting transition temperatures ( T c ) in MRhSi (M=Ti, Zr and Hf) are 5.1, 10.3 and 2.3 K, respectively. These ternary rhodium silicides are new superconductors. The T c (=10.3 K) of ZrRhSi is highest among many compounds with the Co 2P-type structure.