An Aspect of the Fe Distribution of YBa2Cu3-xFexOy: Electrical and Mössbauer Studies | ||||
| Egyptian Journal of Solids | ||||
| Article 8, Volume 25, Issue 1, 2002, Page 83-92 PDF (322.76 K) | ||||
| DOI: 10.21608/ejs.2002.150465 | ||||
 View on SCiNiTO | ||||
| Abstract | ||||
| Oxygen-rich samples of YBa2Cu3-xFexOy with different concentrations have been prepared by solid state reaction in both superconducting (SC) and antiferromagnetic (AFM) phases. Electrical resistivity measurements indicated the preference of Fe to substitute Cu in Cu (1) sites for low iron concentrations in the Sc phase. Mössbauer measurements have been carried out at room temperature, 77 K and 4.2 K in order to elucidate Fe distribution just below the SC-AFM phase transition of x=0.45 and up to x=1. From the analysis of the obtained MS spectra, it is concluded that in the SC phase with x=0.4, Fe substitutes Cu in both square planar and induced pyramidal Cu (1) sites. The latter is formed by oxygen filling the unoccupied O (5) site. With increasing iron content, Fe accommodated in Cu (2) sites prevail, together with the Cu (1) sites of pyramidal configuration. The obtained small QS values for Fe in Cu(2) sites suggest the formation of quasi-octahedral Fe site by additional oxygen atom insertion in the mid plane of the Cu (2)-O bilayer. At 4.2 K, a suppressed hyperfine ordering with Bhf value of 472 kOe is assigned to Fe in Cu (1) sites for the superconducting sample with x=0.4. On the other hand, a hyperfine field of 502 kOe, slightly increasing with x, is suggested to associate Fe in Cu (2) sites with subsequent increase in iron content. | ||||
|
Statistics Article View: 54 PDF Download: 77 |
||||
