Low-temperature x-ray diffraction studies of superconducting Tl-2212 ceramics revealed anomalies in thec cell parameter andc-axis thermal expansion coefficient near the superconducting transition. Air and vacuum anneals in the range 400–550‡C demonstrate that these anomalies correlate with the superconducting properties of the material. The anomalous temperature variation of thermal expansion suggests that the superconducting transition is accompanied by significant changes in the phonon spectrum.

Tl Content and Superconductivity in Tl‐2212 Compounds

Low-temperature structural studies of Tl2Ba2CaCu2Ox

Tl 4{ital f} core levels of Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}, Tl{sub 2}O{sub 3}, and Tl{sub 2}O were measured by x-ray photoelectron spectroscopy in order to elucidate the chemical state of Tl ions in the superconducting oxide. The Tl 4{ital f}{sub 7/2} level is found at 117.4, 118.2, and 118.6 eV for Tl{sub 2}O{sub 3}, Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}, and Tl{sub 2}O, respectively. This result reveals that the Tl valence is between +3 and +1. The creation of holes in Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} is discussed in terms of a charge transfer between Tl ions and (Cu-O) layers. Furthermore, the stabilization of double (Tl-O) layers is also discussed from the viewpoint of structural chemistry.

Tl Content and Superconductivity in Tl‐2212 Compounds

Citations

Low-temperature structural studies of Tl2Ba2CaCu2Ox

References

Chemical state of Tl in the superconductor Tl2Ba2Ca2Cu3O10 studied by x-ray photoelectron spectroscopy.

Tl Content and Transition Temperature in Tl-2223 Superconductors

Related Papers (5)

Tl Content and Transition Temperature in Tl-2223 Superconductors

Superconductivity above 100K in compounds containing Hg

Effectiveness of Bi versus Pb for superconductivity in the TlSr2CaCu2O7 (1212) phase

Formation of Tl-1212 phase in (Tl0.8M0.2)Sr2(Ca,Cr)Cu2O7 (M = Cd and Sc) High-Tc superconductor

Superconductivity in (Tl,Pb)Sr2(Ca,Cr)Cu2O7 and TlSr2(Ca,V)Cu2O7 ceramics