Nano-engineering via intercalation: Layer-by-layer interstratification of high-{Tc} superconducting and superionic materials, Ag{sub x}I{sub y}Bi{sub 2}Sr{sub 2}Ca{sub n{minus}1}Cu{sub n}O{sub 2n+4} (n = 1, 2, and 3)
- Seoul National Univ. (Korea, Republic of)
Through intercalation, the authors have successfully synthesized new materials having layer-by-layer stacking of superconducting and superionic conductor, Ag{sub x}I{sub y}Bi{sub 2}Sr{sub 2}Ca{sub n{minus}1}Cu{sub n}O{sub 2n+4} (n = 1, 2, and 3). According to powder X-ray diffraction analyses, the lattice expansions along the c-axis upon intercalation of Ag-I are {approximately} 7.3 {angstrom} independent on various x values (0.75 < x < 1.2). Superconducting properties were maintained after the intercalation with slight {Tc} depressions. In order to investigate the evolution of electronic and crystal structures of host compound upon Ag-I intercalation and to determine the intracrystalline structure of the intercalated silver iodide, Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) analyses have been performed. According to the nonlinear curve fitting for the Ag K-edge EXAFS spectra, the coordination number for silver in the Ag-I intercalate has been determined to be 4, which is in good agreement with the previous results for Ag{sup +} ionic conductors. This strongly suggests that the new compounds may also have Ag{sup +} ionic conductivity, which has been measured by the a.c. impedance spectroscopy and the pulsed method. All the intercalates have been proved to be mixed conductors with substantial ionic contributions. For example, the ionic conductivity of Ag{sub x}I{sub y}Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (x = 1.09) is about 10{sup {minus}1.5} (ohm {center_dot} cm){sup {minus}1} at 270 C, which is comparable to those of other Ag{sup +} superionic conductors such as Ag{sup +}-{beta}-alumina and Py{sub 5}Ag{sub 18}I{sub 23} (Py = C{sub 5}H{sub 5}NH), with an ionic transference number (t{sub i}) of 0.40.
- Sponsoring Organization:
- Korea Science and Engineering Foundation (Korea, Republic of)
- OSTI ID:
- 548484
- Report Number(s):
- CONF-960163--; ISBN 0-8194-2071-9
- Country of Publication:
- United States
- Language:
- English
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