Crystal structure of the high-temperature superconductor TI2Ba2CaCu2O8

Subramanian, M.A.; Calabrese, J. C.; Torardi, C.C.; Gopalakrishnan, J.; Askew, T.R.; Flippen, R. B.; Morrissey, K. J.; Chowdhry, U.; Sleight, A.W.

doi:10.1038/332420a0

Cited by 426 publications

(57 citation statements)

References 7 publications

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“…A notable comparison, representative of the η = 1 cuprates, can be made between Bi 2 (Sr 1.6 La 0.4 )CuO 6+δ and Tl 2 Ba 2 CuO 6 (denoted as 2201 compounds). Although belonging to different space groups, these materials share one-to-one correspondences between like structural layers, yet exhibit vastly different T C0 values of 34 K [1][2][3] and 80 K [4], respectively; for η = 2, Bi 2 Sr 2 CaCu 2 O 8+δ and Tl 2 Ba 2 CaCu 2 O 8 (2212 compounds) display measured T C0 = 89 K [5] and 110 K [6], respectively, and this tendency continues for η = 3 (2223 compounds). Data for T C0 are cited after Ref.…”

Section: Introductionmentioning

confidence: 99%

Superconducting interaction charge in thallium-based high-TC cuprates: Roles of cation oxidation state and electronegativity

Harshman

Fiory

2015

Journal of Physics and Chemistry of Solids

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Superconductivity in the Tl-based cuprates encompasses a notably broad range of measured optimal transition temperatures T C0 , ranging from lowest in the charge-depleted Tl-1201 compounds (Tl 1-x (Ba/Sr) 1+y La 1-y CuO 5-δ ), such as Tl 0.7 LaSrCuO 5 (37 K) and TlBa 1.2 La 0.8 CuO 5 (45.4 K), to highest in the Tl-1223 compound TlBa 2 Ca 2 Cu 3 O 9±δ (133.5 K). Seven Tl-based cuprates are considered and compared using the model of superconductive pairing via electronic interactions between two physically separated charge reservoirs, whereis determined by the superconducting interaction charge fraction σ, the number η of CuO 2 layers, and the basal-plane area A, each per formula unit, and the transverse distance ζ between interacting layers. Herein it is demonstrated that σ follows from the elemental electronegativity and the oxidation state of Tl, and other structurally analogous cations. The comparatively lower elemental electronegativity of Tl, in conjunction with its oxidation state, explains the higher σ and T C0 values in the Tl-based compounds relative to their Bi-based cuprate homologues. A derivation of σ is introduced for the optimal Tl 2 Ba 2 Ca η-1 Cu η O 2η+4 (for η = 1, 2, 3) compounds, which exhibit a Tl oxidation state at or near +3, obtaining the fundamental value σ 0 = 0.228 previously established for YBa 2 Cu 3 O 6.92 . Also reported is the marked enhancement in σ associated with Tl +1 and analogous inner-layer cations relative to higher-valence cations. For a model proposition of σ = σ 0 , the fractional Tl +1 content of the mixed-valence compound, TlBa 2 Ca 2 Cu 3 O 9±δ , is predicted to be 1/3 at optimization, in agreement with existing data. Charge depletion is illustrated for the two Tl-1201 compounds, where σ < σ 0 values are determined according to substitution of Ba , and/or Tl depletion. Additionally, statistical analysis of calculated and experimental transition temperatures of 48 optimal superconductors shows an absence of bias in determining σ, A, and ζ.

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Section: Introductionmentioning

confidence: 99%

Superconducting interaction charge in thallium-based high-TC cuprates: Roles of cation oxidation state and electronegativity

Harshman

Fiory

2015

Journal of Physics and Chemistry of Solids

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“…The dynamic conductivity is connected to the dielectric function € by the relation e = iV/wto " ia/(2irvc€Q), where o> is the angular frequency, v is the frequency (divided by c), *o 35 8.9 X 10" 12 A-sec V" 1 m" 1 , and c is the velocity of light.…”

Section: B Methods Of Analysismentioning

confidence: 99%

Preparation, characterization, and far-infrared study of ceramic high-Tc superconductors

et al. 1989

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We report on a study of single-phase (superconducting) YBa2Cu;}07 and (nonconducting) Y2BaCu05 and mixed phases of these compounds in bulk and film samples and on an investigation of ceramic bulk material of the homologous series Tl2Ba2CanCun+i02n+6-We describe preparation and structural characterization by x-ray diffraction analyses and further characterization by electric, magnetic, tunnel junction, and Raman scattering studies, and we present results of far-infrared reflectivity measurements. In a theoretical analysis we relate the phonon structure of reflectivity spectra to geometric structure of a metallic network, with holes filled with nonconducting material. The influence of superconductivity on reflectivity is also investigated.

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“…A similar route to BiSr 2 CaCuO,, 6 developed by Beltran et al (41) involves the reaction of Bi 2 CuO 4 , CaCO s , SrCO 3 , and CuO in appropriate ratios. These materials are well mixed and heated to 860°C in an alumina boat under flowing O for 16 hours.…”

Section: Single Cu-o Layer Phase 122011 Tc=i0 Kmentioning

confidence: 99%

“…(40) report the synthesis of BiSrCaCuO . 6 from a prereacted ceramic of "Sr 2 CaCu,OY" and Bi,03. The carbonates or oxides of Sr. Ca, and Cu are first reacted in appropriate ratios at 950"C to form a mixed-phase material.…”

Section: Single Cu-o Layer Phase 122011 Tc=i0 Kmentioning

confidence: 99%