Abstract
Systematical study on the structural stability and superconducting properties of the pseudo-quaternary borocarbide system Y(Pd <sub>1-x</sub> Rh <sub>x</sub> ) <sub>2</sub> B <sub>2</sub> C (0 ≤ x < 0.2) are reported. The LuNi <sub>2</sub> B <sub>2</sub> C-type phase is unstable with the nominal 1:2:2:1 composition in the low (x < 0.05) Rh substitution region. Metastable, multiphase samples with the accompanying superconductivity were observed only in higher Rh concentration region. Superconducting transition temperature T <sub>c</sub> decreases steadily from 23 K in YPd <sub>2</sub> B <sub>2</sub> C (x = 0), to 13.5 K at x = 0.05, to 6.5 K at x = 0.075, 4.5 K at x = 0.1, and 3.6 K at x = 0.15.