Abstract
Using a Raman microprobe technique, we have measured the Raman spectra of single crystallites of Tl2Ba2Can-1CunO2n+4-d (n = 1,2 and 3) with Tc varied by oxygen removal or addition. It is found in Tl2Ba2CuO6-d that the photon modes associated with the vibrations of bridging 02 in Ba-O planes (approximately 485 cm-1) and 03 in Tl-0 planes (approximately 600 cm-1) increase in frequency and become broader as the Tc increases from 0 to 70 K with oxygen removal, while the Ba and Tl vibration modes do not change appreciably. The observations are attributed to the valence change of Tl, resulting from a change in the charge transfer between Tl and (Cu-01), and to the distortion and/or disorder in Tl-0 planes due to the oxygen removal. There is a clear correlation between Tc and phonon frequencies in Tl-based superconductors. We suggest that a change in charge distribution in (Cu-O1)-02-(Tl-03) complexes is responsible for the phonon frequency shifts observed in 02 and 03 vibration modes.
Original language | English |
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Pages (from-to) | 93-105 |
Number of pages | 13 |
Journal | Proceedings of SPIE - The International Society for Optical Engineering |
Volume | 1336 |
Publication status | Published - 1990 |
Event | Raman and Luminescence Spectroscopies in Technology II - San Diego, CA, USA Duration: 1990 Jul 10 → 1990 Jul 12 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Computer Science Applications
- Applied Mathematics
- Electrical and Electronic Engineering