Interface reaction, phase transition, and composition were investigated for Co thin films on amorphous SiC films as a function of heat treatment (600-1000~ Amorphous SiC layers were grown on (001) Si substrate by magnetron sputter deposition. The SiC layers had a 1:1 stoichiometric ratio of Si to C and an amorphous structure containing microcrystals. The interface reaction between a sputter-deposited Co (250.~ thick) and amorphous SiC (2000~ thick) layer on a (001) Si substrate induced by vacuum annealing at temperatures of 600-1000~ was examined. Co2Si was formed at 700~ as the first crystalline phase and CoSi at 800~ as the final stable phase of the Co/SiC interface reaction. This phase sequence of C%Si-~CoSi was interpreted in terms of the effective heat of formation and the calculated ternary Co-Si-C phase diagram, and it was consistent with the experimental results. The high formation temperature of the first crystalline Co2Si phase and no formation of a final stable CoSi 2 phase are discussed in comparison with Co/Si interface reaction and related to the binding energy of the reacting materials. In addition, the behavior of free carbon remaining after the Co/SiC reaction was investigated. This free carbon moved to the top of the reacted cobalt silicide/SiC layer.

Structure and Superconductivity in New Nb-Based Cuprates (Nb,Ti,Cu)Sr 2EuCu2Oz. -Polycrystalline samples of (Nb1-xCux)Sr2EuCu2Oz (0  x  0.5) and (Nb 0.9-xTi0.1Cux)Sr2EuCu2Oz (0  x  0.4) are prepared by calcination of stoichiometric amounts of the metal oxides in air (1010 C, 7-10 h) followed by sintering in O2 (1. 1050 C, 12 h, 2. 1060 C, 15 h). No superconductivity is observed in the resistivity measurements of Ti-free Cu-doped samples and Ti-doped samples. In contrast, the Ti/Cu co-doped sample with x = 0.4 shows a superconducting transition in both electric resistivity and magnetization measurements with a T c (onset) of 30 K. Rietveld refinements of XRD data for the Ti/Cu co-doped samples shows a structural transformation from tetragonal (space group P4/mmm) to orthorhombic (space group Ima2) with the weight fraction of the orthorhombic phase increasing with Cu level. The superconductivity induced by Ti/Cu co-doping is discussed in terms of the change in hole concentration and the structural transformation. -(LEE*, H. K.; KIM, Y. I.; J. Alloys Compd. 646 (2015) 517-521, http://dx.