High-Purity FeSe^sub 1-x^ Superconductors Prepared by Solid-State Synthesis and Liquid Phase Processing

• Published in: Journal of the American Ceramic Society 2010-10, Vol.93 (10), p.3195
• Main Authors: Qi, Xiaoding, Wang, Jiun-Yi, Hung, Chi-Jung, Kuo, Jui-Chao, Yates, Karen, Cohen, Lesley
• Format: Article
• Language: English
• Subjects: Annealing; Ceramic sintering; Ceramics; Gas flow; Materials science; Spectrum analysis; Superconductors
• ISSN: 0002-7820; 1551-2916

... samples have been prepared by a solid-state reaction in the Ar+3% ... gas flow. The samples sintered at 410...C were of the tetragonal PbO structure (β-phase), showing little trace of ...-phase (hexagonal). However, the samples sintered at higher temperatures contained a fair amount of ...-phase, which was unable to be eliminated completely by subsequent annealing at ≤450C for a prolonged period. Both M - T and R - T measurements showed that sintered samples of β-phase were superconducting with an onset ... above 8.1 K. Thick films of ... were grown on ... substrates by liquid phase processing with SeSn as the flux. In contrast to the sintering, the films grown around 910...C from the Sn-containing liquid had a pure β-phase. Although the phase diagram showed some solid solubility of Sn in FeSe, energy-dispersive X-ray spectroscopy failed to find Sn trace in the crystallized films, which showed a steeper superconducting transition at lower ... of 6.0 K. To clarify whether the possible Sn contamination caused the drop of ..., ...:5% Sn samples were sintered, which showed little change of ... from the pure β. The cause for the ... reduction of thick films remains unclear. (ProQuest: ... denotes formulae/symbols omitted.)