Local distortions of the Tl-O layers in Tl-based high-temperature superconductors

Journal Article · Mon Aug 01 00:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.3356· OSTI ID:7174984

Li, G G ^[1]; Mustre de Leon, J ^[2]; Conradson, S D; Lovato, M V ^[1]; Subramanian, M A ^[3]

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1. Electronics Research Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2. Electronics Research Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States) Applied Physics Department, CINVESTAV-Merida, Merida, Yuc 97310 (Mexico)
3. Central Research and Development, E.I. du Pont de Nemours and Company, Experimental Station, Wilmington, Delaware 19880 (United States)

Local distortions of Tl and O(3) atoms from the high-symmetry crystallographic sites in Tl[sub 2]Ba[sub 2]CuO[sub 6] and Tl[sub 2]Ba[sub 2]Ca[sub 2]CuO[sub 8] have been observed by x-ray-absorption fine structure at the Tl [ital L][sub III] edge. The interlayer Tl-Tl distance around [ital R]=3.50 A remains, but the intralayer Tl-Tl distance around [ital R]=3.87 A is not found. The Tl-O(3) distances (in the Tl-O layers) are [ital R]=2.31 A in Tl-2201 and [ital R]=2.35 A in Tl-2212. These results show that both Tl and O atoms are shifted from their ideal crystallographic positions. The differences in the near-edge features of the x-ray-absorption spectra of these materials are consistent with this result. A negative edge shift of 1.2 eV at the Tl [ital L][sub III] edge compared to that of Tl[sub 2]O[sub 3] indicates that the valence state of the Tl ion is less than 3+, which is consistent with charge-transfer models.

• OSTI ID: 7174984
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 50:5; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
CHARGED-PARTICLE TRANSPORT
LATTICE VIBRATIONS
CALCIUM OXIDES
CUPRATES
HIGH-TC SUPERCONDUCTORS
THALLIUM OXIDES
ABSORPTION SPECTRA
ANHARMONIC OSCILLATORS
VALENCE
X-RAY SPECTRA
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
ELECTRONIC EQUIPMENT
EQUIPMENT
OSCILLATORS
OXIDES
OXYGEN COMPOUNDS
RADIATION TRANSPORT
SPECTRA
SUPERCONDUCTORS
THALLIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies