Atomic Disorder and Superconductivity in Ca sub 3 Rh sub 4 Sn sub 13

• Published in: Journal of physics. Condensed matter 1989-08, Vol.1 (33), p.5689-5702
• Main Authors: Westerveld, J P A, Cascio, DMRL, Bakker, H, Loopstra, B O, Goubitz, K
• Format: Article
• Language: English
• ISSN: 0953-8984

Superconducting Ca sub 3 Rh sub 4 Sn sub 13 was quenched from high temperatures. X-ray diffraction measurement gave an indication of the type of defects (Sn atoms on the Ca sublattice) generated at high temperatures that are responsible for the degradation of the superconducting transition temperature. The relative degradation turns out to be approx 10% for each 1% of anti-site Sn atoms on the Ca lattice. Restoration of the superconducting transition temperature by annealing at intermediate temperatures is employed to study the kinetics of the defects. Values are obtained for the vacancy formation energy (1.10 eV) and the vacancy migration energy (0.89 eV). The activation energy for the annealiing of anti-site defects is measured as 2.14 eV ( approx = 1.10 + 0.89 eV), which suggests a vacancy mechanism for diffusion. The pre-exponential factor in the relaxation time for vacancy migration is obtained as 1.3 x 10 exp --3 s and that for annihilation of anti-site atoms as 9.3 x 10 exp --10 s. Graphs. 18 ref.--AA