Interactions between nickel and melted R-Ba-Cu-O (R=Y,Nd)

R-Ba-Cu-O (R = Y and Nd) compounds were melted and crystallized in nickel crucibles. The interaction between these materials was studied by examining the physical aspect of the nickel interface. Interaction mechanisms between nickel and melted R-Ba-Cu-O compounds are proposed to explain the formation of an interface, constituted of a top layer of Ni_0.8Cu_0.2O_x and of an NiO_x underlayer as well as the presence of nickel oxide-rich particles in the melt.