Phonon Raman scattering in Y{sub 1{minus}{ital x}}Pr{sub {ital x}}Ba{sub 2}Cu{sub 4}O{sub 8} ({ital x}=0{endash}1) and (Y{sub 1{minus}{ital x}}Pr{sub {ital x}}){sub 2}Ba{sub 4}Cu{sub 7}O{sub 15{minus}{delta}} ({ital x}=0{endash}0.6)
- Department of Physics, Chalmers University of Technology, S-41296 Goeteborg (Sweden)
- Institut fuer Festkoerperphysik, Technische Universitaet Berlin, Sekr. 5-4, Hardenbergstrasse 36, D-10623 Berlin (Federal Republic of Germany)
- Department of Inorganic Chemistry, Chalmers University of Technology, S-41296 Goeteborg (Sweden)
- Department of Physics, The Royal Institute of Technology, S-10044 Stockholm (Sweden)
- Research Laboratory of Engineering Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227 (Japan)
We report on a Raman-scattering investigation of phonons in ceramic Y{sub 1{minus}{ital x}}Pr{sub {ital x}}Ba{sub 2}Cu{sub 4}O{sub 8} (Y{sub 1{minus}{ital x}}Pr{sub {ital x}}124) with {ital x}=0{endash}1, and (Y{sub 1{minus}{ital x}}Pr{sub {ital x}}){sub 2}Ba{sub 4}Cu{sub 7}O{sub 15{minus}{delta}} (Y{sub 1{minus}{ital x}}Pr{sub {ital x}}247) with {ital x}=0{endash}0.6. It is found that the {ital A}{sub {ital g}} symmetry phonons of the BaO layers and the CuO double-chain layers increase in frequency with Pr content {ital x}, while {ital B}{sub 2{ital g}} and {ital B}{sub 3{ital g}} symmetry phonons decrease in frequency. In the Y{sub 1{minus}{ital x}}Pr{sub {ital x}}247 samples we are able to identify two symmetry allowed apical oxygen {ital A}{sub {ital g}} modes. The {ital B}{sub 1{ital g}}-like plane oxygen phonon softens by {approximately}12{percent} from {ital x}=0 to {ital x}=1, and exhibits a two-mode behavior at intermediate {ital x} in both Y{sub 1{minus}{ital x}}Pr{sub {ital x}}124 and Y{sub 1{minus}{ital x}}Pr{sub {ital x}}247. Polarized micro-Raman spectra of Pr124 crystallites show that several phonons are asymmetric, exhibiting Fano line shapes similar to what has been found in superconducting Y124. The variation in phonon frequencies with Pr content is similar to what has been reported for the single-chain cuprate Y{sub 1{minus}{ital x}}Pr{sub {ital x}}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (Y{sub 1{minus}{ital x}}Pr{sub {ital x}}123), and the changes can be understood from the variation in structural parameters. We do not observe any peculiarities that can explain the disappearance of superconductivity, or the different rates of {ital T}{sub {ital c}} suppression in the three different Y-Ba-Cu-O systems, upon Pr substitution. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 278741
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 53, Issue 6; Other Information: PBD: Feb 1996
- Country of Publication:
- United States
- Language:
- English
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