Abstract
195 Pt-, 139 La- and 11 B-NMR have been investigated in the quaternary superconductors RT 2 B 2 C(R = Y,La,Th and T = Ni,Pd,Pt). The electric quadrupole frequency of 139 La changes almost by one order of magnitude from T = Ni to Pt, indicating that the hybridization of La 5d and d-electrons of the transition element is important and depends largely on the transition element. T 1 T of 195 Pt obeys the Korringa relation in the normal state, but 11 B-1/T 1 T and Knight shift are enhanced with decreasing temperature in some borides. The temperature dependence of T 1 of 195 Pt in ThPt 2 B 2 C below T c strongly suggests that the conventional BCS superconductivity is realized in the quaternary borocarbide.