Kimball, Clyde W.
M.S. (Master of Science)
Department of Physics
Superconductors; Mössbauer spectroscopy
Temperature-dependent Mossbauer measurements have been carried out on the high T[sub c] oxide superconductor (La₁.₈₅Sr₀.₁₅) CuO₄ (T[sub c] = 37 K) doped with tin. Using the 23.88 keV Mossbauer resonance at ¹¹⁹Sn, the valency state of tin ions in the superconductor has been characterized and hyperfine interactions studied. The temperature dependence of the mean-squared displacement shows phonon softening near 75 and 170 K. Above 180 K the data fit to a harmonic model with 0[sub D] ~ 403K; between 77 and 160 K, 0[sub D] = 383K; and below 77 K, 0[sub D] is temperature dependent. Below 250 K, the temperature dependence of the shift indicates that, in addition to a temperature dependent 0[sub D], there are electronic changes characteristic of a phase transformation. The valency of tin is found to be 4+.
Giapintzakis, John, "A mossbauer study of phonon and electron anomalies in perovskite superconductor La₁.₈₅Sr.₁₅Cu.₉₅Sn.₀₅O₄" (1987). Graduate Research Theses & Dissertations. 414.
Northern Illinois University
Rights Statement 2
NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.